Saturday, December 26, 2009

Happy Boxing Day!

Happy Boxing Day

to our Commonwealth friends!

Yes, today is Boxing Day "…on which postmen, errand boys, and servants of various kinds received a Christmas box of contributions from those whom they serve" (Charles Dickens). Surely there are plants for celebrating Boxing Day?

According to the CanadaInfo web site ("over 500 pages of information about Canada!") "….under Queen Victoria…December 26th became a holiday as boxes were filled with gifts and money for servants and tradespeople [!!]…. poor people carried empty boxes from door to door, and the boxes were soon filled with food, Christmas sweets, and money. Parents gave their children small gifts such as Oranges, handkerchiefs, and socks…." There we go: oranges. Probably the same ones they used to fill the toe of the Christmas stocking the day before.

Where did the Victorians get oranges in winter? Perhaps imported from Spain, or grown in the orangerie--a special greenhouse used to cultivate citrus for the fragrant blossoms and exotic fruit. Some citrus will flower off and on at any time of year, especially 'Meyer' lemons and kumquats, and both of these are slow growers especially suitable for growing in pots.

Most citrus have beautiful colorful fruit in the winter, so they show up in many seasonal celebrations and recipes, especially those of Asian, Pacific, and Mediterranean cultures. Bags of oranges and mandarins are traditional gifts anytime during the two-week Chinese New Year's celebration, symbolizing happiness, while kumquats symbolize prosperity. 'Dancy' is the tangy, seedy Christmas tangerine; 'Owari Satsuma' is the nearly seedless, sweet mandarin orange. Both grow very well here, and kumquats are the hardiest, easiest, and most ornamental citrus of all.

Other unusual and hardy citrus with showy holiday fruit include the Rangpur lime (actually a sour mandarin) and the Calamondin (Kalamansi in the Philippines, another prolific sour-fruited small orange). Of course, oranges, grapefruit, lemons, some limes, tangelos, and pummelos all grow readily here, and new summer-fruiting citrus extend the harvest season. All have shiny evergreen foliage, fragrant flowers, few pests, and attractive fruit. Simmer some cut up citrus peel, a cinnamon stick, and a few cloves to scent your house on a gloomy winter day.

One citrus with special holiday significance is citron, the fragrant, thick peel of which is one of those mysterious candied objects in fruit cakes, and the small-fruited 'Etrog' citron is used in the Jewish Feast of the Tabernacles. A bizarre citron with finger-like fruit is the 'Buddha's Hand', grown in China and Japan for the fragrant fruit.
I remember a vigorous argument at the Christmas dinner table between my father and grandfather--both very smart and very stubborn men--about whether citron is a citrus fruit or a melon. They were both right. For the record: much of the citron sold for fruitcake in the United States is the candied peel of a small, thick-rind watermelon.

Anywhere people gather in the winter they cut local flowers, berries, and leaves to decorate their homes, and soon you have a holiday tradition. Stick them in a greenhouse and you have the makings of a big industry (nursery crops were valued at over $3 billion in California in 2001). After all, how did a roadside weed from Mexico (Poinsettia--Euphorbia pulcherrima) become the ubiquitous symbol of the season?
This lanky shrub initiates flowers in response to increasing periods of darkness, providing bright red bracts (the colorful leaves around the tiny flowers) in winter in Southern California and other frost-free areas. Growers long ago learned to control flowering by screening plants in a greenhouse with black plastic (this is why you see mums in bloom in stores all year). Flowering of Poinsettias involves 14 hours a day of total darkness for several weeks from late September on. Even an incandescent light bulb on for a few minutes can stop the process, so Poinsettia growers can't be sloppy!

What should you do with them after the holidays? Enjoy the plant indoors until nearly March, then cut it back, repot it, and move it outside to partial shade if you want to grow it on for next year. Then try to remember to start the dark treatment in late September. Or just let the grower do it and buy a new one next year.

Controlling the length of darkness (called the photoperiod) allows growers to time the production of other holiday plants. Thanksgiving and Christmas cactus have interesting flowers in shades of pink, lavender, orange and white. These are two different species of Schlumbergera, usually called Zygocactus (an old botanical name) and now thoroughly interbred so they are just called Holiday cactus. Rhipsalidopsis is a related cactus that blooms in spring, so it's called Easter cactus--at least until we become truly ecumenical and call it Spring cactus.

Confused yet? It gets more complicated, as the bloom is a response to an interplay of day length and temperature. Unlike Poinsettias, these WILL set flower buds during cool fall nights even if there is light, but won't set buds if it's too warm (such as inside your house, so don't bring them in too early). They will drop the buds if it's too cold (such as outside in the winter). Consequently, successful holiday cactus are kept year-around in screened porches where they can flower in response to the declining days and temperatures, or are brought indoors after the buds begin to develop.
Kalanchoeis a photoperiod-sensitive succulent with vivid, neon flowers in 1970's colors. Easy to grow but too tender to leave outside during the winter, it is hardy enough for the porch.

Our mild temperatures enable us to easily grow winter flowers that gardeners in colder climates have to protect. For example, paperwhite Narcissus are often "forced" into bloom indoors in snowy regions for their powerful, sweet scent.

These subtropical relatives of daffodils naturally flower here in late fall and early winter--often as early as November, indoors or out. You can make them bloom indoors in just 8 - 10 weeks by setting them in rocks and water. Stick them in the ground or in a large pot after they've bloomed, allow the foliage to grow out and then die down naturally in late spring. They will multiply freely in the garden and bloom year after year. Oranges and winter flowers in your back yard are part of what originally lured folks to the Golden State!

So, I invite all our Canadian and British friends to stop by this Boxing Day. Bring us the gifts and money, and we'll give your kid an orange. Or maybe some socks.

Published in the Davis Enterprise, December 26, 2002

Sunday, December 20, 2009

Woodman, Spare That Tree!

Pruning season is upon us....

"Put down the chain saw, sir, and step away from the tree!" It's pruning season again. A time when we rejuvenate our fruit trees and roses, make our shade trees safer and stronger, and increase next season's bounty of flowers and fruit. But it's also the time of year when the combination of y-chromosomes and 2-cycle engines can cause irreparable damage in the landscape.

Rule #1: a chain saw is not a pruning tool. It could be in the hands of a skilled professional. But for the most part, chain saws are excellent for cutting firewood, cutting up wood which has already been removed from the tree, and sculpting logs into garden art. For that matter, machetes, axes, and hatchets are not pruning tools, either. They are brush-removal tools.

Rule #2: shade trees should be pruned by qualified professionals, or after you have been properly trained. A certified arborist can assess your trees for you. Most shade trees which have been trained properly when young need very little pruning when mature. It's mostly a matter of removing crossing branches, branches which are too closely spaced (<12" apart on the trunk) or are at weak angles (30 or 45 degrees). Branches should be removed in stages and cut to leave a collar.

Good pruning tools make the job easier and more effective. My primary pruning tools consist of a folding saw, a pair of hand-held bypass pruners, and a lopper. A pole saw is useful for pruning fruit trees and light thinning of shade trees. I have found pole loppers cumbersome and dangerous, though they are handy for topping tall hedges and for summer pruning of fruit trees. Sharpen the cutting blades of pruners frequently with a flat file, and keep them oiled.

What do we prune now? Roses, deciduous fruit trees, deciduous vines, and shade trees. Hardy evergreens can be pruned anytime fall through spring; avoid pruning them during very hot weather. Our general goals are to open up the structure of the plant, control the size if necessary, make them safer (better branch structure), increase the flowers, and reduce diseases. See our separate articles on rose and fruit tree pruning. Today we're going to focus on other flowering woody plants.

What are the plants we don't prune right now? Subtropicals are best pruned during warm weather. That includes evergreen fruit trees such as citrus and avocadoes. They are somewhat tender, and open pruning wounds are vulnerable to frost damage. The only reason to prune Citrus trees is for size control or aesthetics. Unlike other fruit trees, we don't need to reduce the amount of fruiting wood. Prune anytime between March and October.

Subtropical plants which have been damaged by freezing weather should be left alone until spring. The cold snap on December 18 and 19 did a lot of top damage to plants such as Angel's trumpet, bananas, Bougainvillea, and Lantana. The freeze wasn't cold or sustained enough to have killed them, but they look pretty bad. You can gently tug off the blackened leaves and stems if you like, although they actually do provide some measure of continued frost protection simply by 'cloaking' the remaining parts of the plant. Wait until new growth begins in the spring, then cut back to that. As with citrus, pruning may make the plant vulnerable to further damage. The plant will tell you when and where to prune.

Hardy deciduous shrubs, trees, and vines which flower in the spring could be pruned now. It wouldn't hurt them. But since we mainly grow them to enjoy the flowers, why not wait until after the bloom? This includes shrubs such as Chaenomeles (Flowering quince), Deutzia, Forsythia, Lilac, Spiraea (Bridal wreath), and Wisteria. Trees grown primarily for their flowers include crabapples, flowering and red-leaf plums, flowering cherries, and saucer and star magnolias.

Garden books will tell you that these plants bloom on "old wood." If you look closely, you can see the fat flower buds, which formed last summer, all ready to open. In fact, you can cut branches of these and bring them into the house to get an early blossom indoors‹especially plums and quince. The main purpose of pruning these shrubs and trees is to control the size or enhance the form. Head them or thin them just after the bloom. Wisteria is primarily pruned to control the rampant growth. You can cut off vigorous shoots anytime, including summer. The flower buds are very obvious now, so if you want to prune just work around them. But if you need to cut Wisteria back severely (it can get a little out of hand), just enjoy the blooms first.

If it is a deciduous shrub or tree which blooms in the summer, chances are it flowers on "new wood" and can be pruned now. The best example that is common locally is crapemyrtle (Lagerstroemia). It blooms at the end of new growth, so no matter how hard you prune it back it will still flower. As such, it's an ideal plant for people who like to prune! As long as you leave it alone once the season's growth has begun, you will get flowers. I have a crapemyrtle seedling which sprouted in a perennial border, where I don't want anything bigger than 3 ­ 4'. So I just cut it to the ground each winter, and it blooms as a nice low shrub each summer.

If your crapemyrtle's size is not a problem, just trim off the seed heads now (or do nothing at all). If you want to keep it a particular size, just cut out an amount equal to last year's growth. Most varieties grow 2 ­ 4' a year, so that's how much you'll need to remove to maintain a particular height. Although you can head the growth if you must, it will look better if you can cut to a point where an existing branch already is growing.

Hydrangeas seem to perplex folks, especially the large "mophead" hydrangeas (H. macrophylla). These are the types that come in pink or blue, with flower heads 6" or more across. Pruning in the winter, or too late in the summer, reduces flowering considerably. They mostly bloom on "old wood" which forms in mid to late summer. So if the gardener in your household prunes your old-fashioned hydrangeas when he prunes the roses, you aren't going to get flowers. There are some new types such as 'Endless Summer' which rebloom on "new wood."

The fact is that hydrangeas don't need to be pruned at all. But if the shrub has grown too big, cut it back after the spring bloom, but before August. Older shrubs can be thinned by about 1/3 to rejuvenate them, sparking new shoots from the base. These guidelines also work for Oak-leaf hydrangeas (H. quercifolia), which are also easier and generally better-looking shrubs in the Davis area because they're not fussy about our soil and water conditions. PeeGee Hydrangeas (H. paniculata) conveniently bloom on new wood, so you can whack them to the ground in the winter if you like. If you want way more information than you ever though possible about hydrangeas, check out

Prune in winter: roses, summer-flowering trees, hardy fruit trees, shade trees.

Prune after they bloom: spring-blooming shrubs, trees, and vines.

Prune spring through fall: subtropicals.

Prune fall through spring: hardy evergreens.

Prune with a chain saw? Nothing, ever!

"Woodman, spare that tree! Touch not a single bough! In youth it sheltered me, And I'll protect it now."
-- George P. Morris (1802 - 1864)

From the Davis Enterprise Dec, 26th 2006

Thursday, December 10, 2009

Those holiday plants!

What to do with those holiday plants?

Someone gave you a plant for the holidays -- now what?

Many plants have become associated with the holiday season, brightening our homes during these gloomy December days. If you think of most of these plants as nice, long-lasting flower arrangements that you will discard after they finish blooming, you won't be disappointed. Some, however, can be grown on for years with special care, and others can simply be planted in the garden. Parents of young children and pet-owners should be aware that some are poisonous.
The Poinsettia (Euphorbia pulcherrima) is remarkable in that in just 75 years it has become THE Christmas plant.

This roadside weed from Mexico has been bred (largely by the Ecke family in Southern California) to the point that nearly 100 million of them are sold worldwide every Christmas. This in spite of the fact that more than 60% of the public incorrectly believes them to be poisonous! The showy part of the plant is a bract, which is a leaf, and the flowers are the small yellow parts in the middle.

Care during the holidays:

Make your house like Mexico! The Ecke Ranch website ( states "if you are comfortable, so is your poinsettia." Poinsettias definitely don't like to be below 50F, and don't like drafts or cold winds. The brightest room in your house is best. Water just when they go dry, and tepid or warm water is better than cold tap water.

After the holidays:

Poinsettias will begin to drop leaves in February, and then will go dormant. You can reduce watering at that time, and as soon as frost is unlikely (late February) you can move the pot outdoors. Cut them back 50%, repot into a larger pot, and start watering. Start feeding with Miracle-Gro or a similar fertilizer as new growth begins.

Getting them to bloom again is tricky. From late September Poinsettias need 14 hours of complete darkness (not even exposure to a simple incandescent light bulb!) for several weeks to trigger blooming. ANY disruption of that photoperiod requirement will prevent blooming!
Kind of a hassle. -- What did you pay for this plant?
Just buy a new one next year!

Not at all!
Don't get me going.
Poinsettias are NOT POISONOUS!
No part of the plant is poisonous! Nursery people have even eaten leaves on TV to prove it!
No amount of leaves stuffed into lab animals was able to cause a toxic reaction, nor was any amount of application of the sap.

"Thom David, marketing manager of the Paul Ecke Ranch in Encinitas, California, has a way of convincing people ... . He's been known to grab a few bracts off the nearest poinsettia plant and eat them in front of persistent disbelievers. Seems to work, too - they don't doubt him after that.
Speaking from "bitter" experience, he says it's unlikely a kid or an animal will eat more than one bite. He describes the taste as far worse than the most bitter radicchio. Frankly, he says, the flavor is indescribably awful."

Holly (Ilex species, especially Ilex aquifolium 'Variegata') is enjoyed for the long-lasting, clean shiny foliage which is great in wreaths and arrangements, and the bright red berries.

Holly is an excellent garden plant that prefers protection from the hottest sun. Male and female plants of English holly are needed to get berries (and nurseries don't sell them by sex!), but some varieties of other species set berries reliably without cross-pollination. Often described as preferring acid soils, I find that hollies do well here without special attention if the soil is amended when they are planted and if they aren't drought-stressed. Avoid the hottest afternoon sun.

The berries are described as causing "minor toxicity" in the Regional Poison Control Center guide, and the botanical name of our native holly, Ilex vomitoria, gives an indication of the symptoms.

Ivy (Hedera helix) is being used more and more for winter greenery and as filler in winter arrangements.

The smaller-leaved varieties such as 'Needlepoint' or 'Hahn's' are preferred. Ivy can be grown into rings, wreaths, "poodles," cones, or other shapes. Ivy makes a great indoor plant if it is washed off periodically to prevent spider mites, and can be kept outside in morning sun or the shade of a tree. It is completely hardy in our climate, so it can live outside year-round. Ivies can become invasive if planted in the garden, so keep them in pots.

Yes -- leaves and berries cause major toxicity, and the symptoms are very unpleasant.

Amaryllis bulbs (Hippeastrum hybrids) are among the easiest plants to grow and bloom during the holidays, and have stupendous large flowers in shades of red, pink, and white.

Amaryllis naturally bloom in the early summer. These bulbs are produced in Holland and South Africa. Those from Holland have been forced into dormancy and will bloom 2 – 3 months after planting. Those from South Africa think they are in the summer, being from the Southern hemisphere, and will bloom right away.

Give Amaryllis water every few days until the bloom is done. Cut off the spent bloom spikes and allow the foliage to grow indoors until frost danger is past. I've had my best results simply planting these in the ground in partial shade or full morning sun, in average soil. They will bloom in future years in the early summer. Watch for snails! It is possible to get them to bloom for future Christmases by forcing them into dormancy in the late summer (withhold water), but it doesn't always work.

One reference: "The principal irritant is present in small amounts so large quantities of the bulb must be eaten to cause symptoms (diarrhea, nausea, vomiting)."

Pure white Paperwhite narcissus (Narcissus spp.) and their related varieties ('Soleil d'Or' is gold; 'Chinese Sacred Lily' is white with a light yellow center) are also very easy to bloom indoors for the holidays.

The fragrance is powerfully sweet!
This bulb multiplies very freely outdoors in the ground here. Keep watering the pot they are in, or the bowl, or whatever, until they finish blooming. The brighter the situation, the less floppy the leaves will be. After the holidays, stick them in the ground. They'll multiply freely in sun or light shade, and will increase for years. I'm still enjoying flowers from bulbs that old-time Davis resident and botanical illustrator Dr. Addicott brought me 20 years ago.

The bulbs can cause "major toxicity."

Kalanchoe blossfeldiana is an unpronounceable recent addition to the holidays (try Kall-ann-koe-uh).

Growers have developed varieties of this succulent with blooms in neon colors -- shades of orange, pink, cerise, and red -- which hold for many weeks. Too tender to be outside in the winter here, they can live in a pot with little care for months or years and need very little water. They won't bloom again as densely or compactly as the original plant did, but can put out sprigs of bright blossoms in the spring and summer. Keep these in the brightest part of your house while they are in bloom, and water only when dry. Transplant into a larger pot after it finishes blooming, and put in out in morning sun or the shade of a high tree after frost.


Azaleas (Rhododendron species) sold during the holidays are new varieties with a prolific, long bloom.

A little tender in our climate, so they might be damaged in freezing weather (unlike their hardier garden cousins). Typically they are grown in soil with a high amount of peat moss, which makes it tricky to water them correctly, and they are usually incredibly root-bound. If water just puddles on the surface, or runs down the side of the pot, the peat moss has dehydrated and the pot needs to be set in a bowl of water to rehydrate.
If you're going to plant these in the garden, amend the soil heavily with a soil mix that's special for acid-loving plants., and plan on fertilizing regularly with an "acid-type" fertilizer. Tear the roots apart as you plant them to reduce the root-bound condition. Water very carefully as we get into hot weather, making sure to water the root ball thoroughly about twice each week.

"Major toxicity," and the foliage may cause dermatitis (skin rash).

Mistletoe is an oddity.

This semi-parasitic plant grows entirely on other plants but also photosynthesizes to create food for itself. The mistletoe of Christmas is probably in the genus Phoradendron, as are several of our native mistletoes. A quick review of Munz' definitive California Flora describes it as a "large genus of the Americas," with the species Phoradendron tomentosum ssp macrophyllum on sycamores, poplars, willows, ash trees, walnuts, and persimmons [and birches] in the Sacramento valley and other areas." This is the one on older trees all over Central and East Davis, and certainly not the species the druids prized on their oak trees. Birds enjoy the berries and then spread them from tree to tree in their droppings.

My reference books were ambiguous, so an operator at the Poison Control Center (1-800-342-9293) commented that ingestion of a couple berries or leaves would lead to severe vomiting and diarrhea. She also referred us to an excellent web site -- -- for more information about poisonous plants.

Enjoy your holiday plants -- carefully!

Published in the Davis Enterprise, 28 December 2000

Saturday, December 5, 2009

Freeze alert for the Sacramento Valley

Freeze Alert!

December 5, 2009

Temperatures Monday night and Tuesday morning are likely to drop into the mid-20's! Expect frost damage on subtropical plants. And watch the weather: lows in the upper teens and low 20's can cause serious damage to citrus trees and other subtropicals.

National Weather Service link for Sacramento.

Plant protection tips--

Cover plants:
lightweight spun plastic fabrics usually sold as "floating row covers," or frost blankets can simply be draped over the plant, as they are light enough that there won't be damage from contacting the foliage. If you use any material that isn't clear, you need to remove it during daylight hours. Plants can't live without light! Wrapping the trunk with burlap can help prevent major damage in a severe freeze; probably not necessary this time.

Move plants: pull potted plants up against a south or east wall, under an overhang. Reflected or retained heat from warm walls or cement walks will provide additional protection. Protect from cold wind. Fences or walls will prevent additional stress from cold winter winds. If practical, pull the container into your garage for the next few days.

Water: make sure all plants, especially those in containers, are well watered. If dry soil freezes, it will pull moisture from the roots, causing them damage. If the soil is moist it can freeze without harming plant roots.

Spray with an antitranspirant? Though research results are mixed, products such as Cloud Cover or Wilt-Pruf applied just prior to cold weather may give the foliage 3 - 4 degrees protection against the cold as well as desiccating winds.

Provide a heat source:
Christmas lights hung in citrus trees have proved very successful, even with temperatures in the teens. Landscape lighting and portable shop lights will work as well. Make sure the light source is plugged into a grounded extension cord approved for outdoor use.

Harvest fruit? Your call. This is a short-duration freeze, unlikely to do significant damage to the fruit of most varieties. Thin-skinned varieties of citrus could be damaged, especially those on the outer part of the tree (unprotected by foliage).
You may wish to harvest lemons (especially Meyer), and limes, as they are ripe now and will deteriorate quickly if damaged. Freeze the juice for later use. Mandarins that are outside the foliage might be damaged. Thicker-skinned types such as navel oranges will probably be adequately protected by covering the trees, but they are also ripe and could be harvested. Avoid harvesting Valencia oranges, grapefruits, and tangelos, as they don't ripen until later in the spring. Citrus fruit does not ripen further off the tree.

Cold as it is, this will not likely break the record for temperatures set in 1990, when we had 13 consecutive mornings below freezing, with low temperatures on Dec. 22 and 23 of 18 and 17 degrees. The freeze of January 2007 equaled the number of days, but not the absolute low temperatures, of the 1990 freeze.

Here are the temperature data for the 1990 and 1998 freezes.

For more articles about frost and freeze: The 2007 freeze
general frost protection guidelines,
Frost vs. Freeze,
and Winter Care of Citrus.

Some plants that may be severely damaged or killed:

Australian tree ferns


Bougainvillea (older plants likely to recover)

Hibiscus (tropical)

Mandevilla (evergreen types)

Serious damage, but likely to resprout:


Brugmansia (Angel's trumpet)

Bananas (mostly killed to the stem)

Citrus trees (limes and young trees are most vulnerable)

Hardenbergia (Lilac vine—expect damage to the flower buds; maybe no lovely purple flowers this winter!)

Jasmine (true jasmine; Star jasmine is fine).


Palms -- some, particularly Queen palm (outer fronds will dry up and look dead, but the growing point is protected inside the center of the tree).

Pandorea (Bower vine, considerable top damage)

Passifloras (cut 'em to the ground in late spring; they'll be back)

Potato vines (the purple ones look worse than white, but mine recovered in 1990)

Red trumpet vines (severely damaged, unlikely to flower this summer)

Any decision about replacing plants should wait until we've had several weeks of warm weather. Subtropicals can be surprisingly resilient, and may resprout as late as May. So don't be in a rush to pull them out.

Friday, December 4, 2009

Those UC Davis Arboretum All-Stars!

About the Arboretum All-Stars

If you're looking for ideas in the "off" gardening seasons - the heat of summer or the waning days of fall - a walk in the arboretum can be helpful. On a sparkling November day I parked near Mrak Hall and wandered east toward the redwood grove, making note of what had seasonal color or interest. Before you even enter the arboretum you can see a plant unique to Davis. Toyon (Heteromeles arbutifolia) is a native shrub whose abundant berries are turning bright red now.

Their winter color leads to a second common name: California Christmasberry. A number of years ago a yellow-fruited variant occurred, and a nice specimen is growing just at the corner of Old Davis Road where you turn in towards Mrak Hall. This variety is now called 'Davis Gold'. While you might think a yellow berry would be less interesting than the seasonal red of the traditional species, I noted that the lighter-colored fruit stands out better against the dark green foliage.

Toyon (Heteromeles arbutifolia) is sometimes called California Christmasberry

This popular native shrub grows slowly to 10' or more, with flowers that attract beneficial insects and winter berries that attract songbirds. The species, shown at top, typically has red berries, but this golden-fruited variety called 'Davis Gold' originated right here at the UC Davis Arboretum. Check their sales for availability, as it is uncommon in the trade.

There were some very early blooms on the winter currants (Ribes), and a stray California poppy (Eschscholzia californica) was peeking out. Both are really winter and spring bloomers, and there was not much else going on in the California Native Plant garden, except, of course, the tree squirrels scampering everywhere.

A flash of color around on the west side of Putah Creek drew my eye. Rosa chinensis 'Mutabilis' is a very robust old China rose that has a unique quality: the blossoms open light apricot-yellow, then (contrary to most flowers) darken as they age through pink to red (hence the name "mutabilis"). The blossoms are a single row of papery petals, usually twisted and splayed. With upright petals in all colors, all on the plant at the same time, it has sometimes been called the Butterfly rose because it looks as though dozens of butterflies have alighted on the bush.

The Butterfly rose is usually listed in references as Rosa chinensis 'Mutabilis', but the Arboretum All-Star list now has it under the name R. x odorata 'Mutabilis'. The delicate-looking flowers consist of a single row of petals which open yellow, then darken through pink to red. Dozens of blooms are open on the plant at a time, from April through November.
This is a large shrub! It can reach a height of 7 - 8' tall with equal spread.

Roses in November? Sure. Northern California gardeners often enjoy a last flush of bloom on rose bushes even as they begin to go dormant. Some will set a crop of colorful hips as well; the rose hip is just the fruit of the bush. Toyon, currants, and the Butterfly rose have one thing in common: they are all on the list of Arboretum All-Stars.

(I notice that Rosa x odorata 'Mutabilis' is the currently accepted name of the Butterfly rose used on the All-Star list, but nearly every other reference is likely to have it by the older name I used above. Someday I will write a column about why taxonomists change plant names.)

A few years ago the staff at the arboretum began compiling a list of plants that do well in the Sacramento Valley. The stated basis for selection as an All-Star: "100 tough, reliable plants that have been tested in the Arboretum, are easy to grow, don't need a lot of water, have few problems with pests or diseases, and have outstanding qualities in the garden. Many of them are California native plants and support native birds and insects. ... The vast majority of All-Star plants can also be successfully planted and grown throughout California."

I love this list, but frankly it is beginning to drive retailers and landscapers a little crazy. Not because of the list itself or the plants on it, but because of public misconceptions about it. It is not intended as a definitive list for the region, and availability can be a problem.
If I were making any criticisms, it would be that some of the plants are easy to kill: winter daphne, and natives such as ceanothus, manzanita, and western redbud are all notoriously easy to over-water. Some plants tolerate drought while others require it; many California natives are vulnerable to crown rot fungus caused by summer watering. The list is light on trees, and those selected are mostly unavailable in the nursery trade (perhaps their inclusion here will interest some wholesale growers in propagating them). But those are minor concerns, and I have been told that another 50 or so recommendations are on their way.

What it is:

An excellent list of many plants that do well in our area.
A great starting point as you select plants for your landscape design. With two ferns, seven grasses, 35 perennials, 42 shrubs, 8 trees, 6 vines, you can find ideas for a new landscape or a renovation project. One-third of them are California natives. Many are unusual, perhaps helping you think outside of the traditional options.

What it is not:

Read more

Wednesday, November 25, 2009

The Edible Plants of Thanksgiving!

My New England grandmother put on a classic Norman Rockwell Thanksgiving dinner each year. Many of you could probably recite the menu, and it never varied. Oh, at one point she added mashed turnips to the fare, because my father's mother had told her that my father loved them. This was patently untrue, and neither did anyone else, but there were some things you just didn't tell Grandma. So year after year the dish of lovingly mashed and buttered turnips sat untouched. But now I have a son who loves braised turnips with the holiday meal.

The modern menu has become a mix of foods from around the world. But it is still heavy on the fruit, roots, and grains of our American natives—albeit eastern natives and plants originally domesticated from central and South America. Cranberry sauce, succotash, the starchy side dishes and pies all have American origins. Some of the plants can be grown here; others have special requirements that would make it difficult.

I have a vivid memory of a rather tense discussion between my father and grandfather about the origins of that hard, candied fruit that sticks in your teeth when you eat fruitcake. One said it was a citrus, the other said it was a melon. These were two proud men, each sure of his position. The oldest child was eventually dispatched upstairs to look it up in the encyclopedia. The answer is at the end.

So to help your family resolve these factual disputes, here is some basic information about the Thanksgiving comestibles!

Vegetables and snacks:

The colonists didn't have any of these!

Vegetable sticks:

* Carrot -- Daucus carota sativa, and
* Celery -- Apium graveolens dulce.

These are cool season annuals; celery is from Europe and Asia, and carrots are probably from Afghanistan. Planted in early fall for winter and spring crops. Celery is surprisingly easy to grow, but a little tricky to blanch for the pale stalks you see in the store. So garden celery is green and has strong flavor.Carrots require loose soil or the roots will be misshapen, and the seed takes a long time to germinate. So it is often planted together with'

* Radishes -- Raphanus sativus

From the Mediterranean. Family: Brassicaceae (Mustard). Radish seeds germinate in days, and are ready to harvest in 3 – 6 weeks. Planted in fall or early spring in loose soil. The carrot seeds will just be sprouting as you pull the radishes.

* Olives -- Olea europea

Small tree, grown in full sun. Easy, ornamental, drought tolerant. Common allergy plant.

Mediterranean. Family: Oleaceae

Soaked in water, brine or lye to remove the bitter glucosides. Usually cured from green olives in California, then some are processed by bubbling air through the solution to make them turn black. Black (ripe) fruit are used for Italian and Greek-style olives.

Read more....

Written for the Davis Enterprise, November 24, 2005

Tuesday, November 17, 2009

Noshing in November!

November is all about food.

"You should make a harvest calendar," someone said to me recently: a list of what we can harvest, month by month, from our garden and landscape. I like a challenge. It's easy to have bounty from your back yard, in, say, July. One peach tree can produce hundreds of fruit. With stone fruit varieties available to ripen as early as May and as late as October, a well-planned and rigorously pruned family orchard can readily yield from late spring into early fall. Citrus varieties ripen winter and spring, with some outliers into the summer and beyond (kumquats and Meyer lemons can have ripe fruit all year).

By now most gardeners have pulled their tomatoes, perhaps planted a few winter vegetables. The fruit trees are dropping their leaves. Perhaps grandmother made jams and preserves from the summer garden to enjoy during winter, but "putting food by" is a less common practice nowadays. What could be in your harvest basket in November and December?

A November harvest basket!
Clockwise from the upper rose: 'Owari Satsuma' mandarin, Feijoa; turnips, sweet peppers, rose hips; walnuts; hot peppers; Arbutus (small white blossoms). All surrounded by Ginkgo leaves.

The vegetable garden.

We almost always have sunny, dry weather here in the fall. While I have pulled most of my tomatoes, I was still harvesting fruit into November. Nights in the 40's and a couple of rainstorms put an end to that. But don't pull your pepper plants, if you have room: the green fruit that have set in late summer will continue to ripen nearly until frost.
This year we built a new vegetable planter primarily for root vegetables. I was curious if we could get winter vegetables going early enough to harvest for the Thanksgiving meal. Root vegetables like loose soil, and I decided that the easiest way to accomplish that was with a raised bed. So 2 x 12's were hammered into a 4 x 8 rectangle. The soil was amended with 2 parts compost to 1 part native soil, dug thoroughly to a depth of about 18 inches. A mini-sprinkler water line was attached and run nearly daily. Seeds were planted in early September: radishes, carrots, turnips, and beets. I could have planted parsnips, but my suspicion is that nobody would eat them; maybe next year.
Voila! Radishes were ready in October. Turnips will be on the Thanksgiving table, parboiled and then braised in butter and pepper. Beets are just bulging, so they will be later holiday fare. And the carrots look to be at least a month or so away. Brussels sprouts planted nearby have just begun to form their odd little side sprouts; six plants may produce enough for a small side dish now, with lots more to come as they mature up the stem. Lettuce and other salad greens can be harvested within a few weeks of planting; likewise Pak choi and Swiss chard. And all of these will continue to yield through the winter and spring, until hot weather returns.

Continue reading....

Saturday, November 7, 2009

De-puckering persimmons?

Puckery persimmons?

From the Davis Enterprise, December 27, 2007

We get questions....

I've heard there is a way to pick persimmons and ripen them so they aren't astringent.

Of the dozens of Oriental persimmon varieties, two are commonly grown in California. Fuyu persimmons are flattened on the bottom and are non-astringent. They can be eaten as soon as they turn orange (November), having a mild, sweet flavor and a texture firm enough to munch like an apple or add to fruit salad. They also dry nicely, sliced thin and layered in a fruit dehydrator for a few hours. Dip the slices in melted chocolate for an elegant touch.

Hachiya persimmons are elongated and have a point on the bottom of the fruit. They turn color in November but aren't edible until December. Hachiya and other astringent persimmon varieties, including the native American species, are famous for their astringency when under-ripe, and for their gelatinous texture when ripe. Many people are put off by the gooshy ripe fruit, but Hachiya has a richer flavor and is more prized for cooking.

Astringency in persimmons is caused by tannins, the same chemicals that make tea, red wine, and unripe bananas and peaches cause your mouth to pucker. Tannins cause the surface of your tongue and mouth to constrict and stop salivating: 'it will drawe a mans mouth awrie with much torment,' said Captain John Smith upon tasting the American 'putchamin' in Virginia. Mmmm. Yet fully ripe, with the flesh nearly liquid, they are described as luscious and honey-like.

The USDA tried over a number of years to introduce persimmons to growers and consumers, and sought to overcome the astringency and mushiness of the fruit in order to broaden its appeal. Observing the process of ripening employed in Japan and China, they saw the hard, unripe fruit:

--immersed in a mix of water and lime for several days.

--sealed in a covered earthenware jar with a burning stick of incense for a day or two.

--buried in mud for several days.

--packed in sake casks just after the sake was drawn off, immediately sealed air tight.

Each of these techniques left the fruit firm, ripe, and non-astringent.

Continue reading.....

Sunday, November 1, 2009

Plants with colorful winter fruit!

Pyracantha berries are turning color, citrus have their first ripening blush.
Here's a list of plants to provide color in the landscape in the winter.

Saturday, October 24, 2009

Guavas and quinces and other edible ornamentals

from the Davis Enterprise, October 22, 2009

Strawberry jam and a marketing ploy prompted this column.
One grower started labeling some of their attractive winter vegetables "ornamedibles" to suggest to customers that they leaves were pretty as well as edible. Ok, it makes a good point, but it's a little too cute for me. Garden writer Rosalind Creasy came up with a more staid term in her book The Complete Book of Edible Landscaping, originally published by Sierra Club Books in 1982 and due for an updated edition in January 2010: edible landscaping. The idea is simple: mix edible plants into your landscape. Choose landscape shrubs and trees that happen to provide food as well as beauty. Grow your vegetables, flowers, and herbs together for mutual benefit (the herbs and flowers draw beneficial insects for the vegetables, among other things).
Some common landscape shrubs meet these criteria: rose hips (fruit) can be used in tea, for example. Others aren't as well known, but include some adaptable shrubs and vines. Many of these plants help fill the harvest basket in fall and winter.

Myrtle family

An unassuming little shrub in the myrtle family came our way the other day. It has tight, shiny dark green leaves, and a compact growth habit. Scattered along the branches were dark reddish-purple fruit, about the size of blueberries. Arising from the plant was a wonderful aroma of strawberries and guavas. It smelled just like fresh strawberry jam! The little berries had a sweet/tart flavor and a mealy semi-juicy texture.
Ugni molinae is the odd name of this delightful little shrub. Native to Chile and parts of Argentina, it is sold by the common name Chilean guava. Ugni is a rare case where an indigenous name has been used for the botanical name; usually taxonomists use Latin (rarely Greek) names. In southern Chile the fruit is combined with hard liquor and syrup to make a liqueur called Murtado, which translates to "little myrtle."

Ugni: Chilean guava
Chilean guava will take full sun or shade, average water or drought, growing to 6' or so if you let it, but can be readily pruned to keep it small. Plant this near a window where you can enjoy the aromatic fruit, or near a path for quick nibbling. Adaptable, ornamental, and edible.

Feijoa: pineapple guava
Another shrub with edible fall fruit, also in the myrtle family and originating in South America, is Feijoa sellowiana, commonly called Pineapple guava.....
Read more

Thursday, October 8, 2009

Ask the nursery guy!

Why do leaves turn color in the fall?

This is right up there with 'how do they grow seedless watermelons?' among the most-asked questions directed at plant professionals.

The answer is simple! The days get shorter, the nights get colder, and Jack Frost magically paints the....
Well, actually, the answer is more complicated, involving daylength (actually nightlength), temperature, nutrients, and genetics.

Trees that have adapted to cold winter climates go through several steps as winter approaches. The first part of the process is a reaction to longer nights. The plant forms a layer at the base of the leaves that blocks the movement of carbohydrates (sugars, starches) out of the leaves, and blocks the movement of minerals into the leaves. That 'abscission' layer eventually gets brittle and breaks, so the leaf falls.

But before that happens, the plant produces less and less chlorophyll because it has less stuff to make it from. That is the pigment which makes leaves green. It is also the most fragile pigment, breaking down in sunlight very quickly. Usually the plant is replenishing it very quickly. But as it breaks down and becomes less abundant, the less common pigments of yellow and orange become visible. So these are the first fall colors that we see. Those colors were already there; we're just seeing them now because the green is gone. This first reaction mostly follows the calendar, although severely drought-stressed plants will begin to go dormant earlier than normal.

Some minerals are mobile within the plant, moving from one place to another as needed. The plant moves phosphorus out of the leaf and into the stem where it is stored during cold weather. The absence of phosphorus changes the chemical reaction in the leaves, and the remaining trapped carbohydrates are now made into certain other pigments, notably the ones that are red and purple. So these are the more spectacular colors that we see next. They weren't there before; the tree is making them now out of what's left in the leaf.

Some trees make more of these pigments than others do, so it varies between species. There are also genetic differences of seedlings within a species. Variation in temperature from year to year, and the nutrient status of the specimen, also affects fall color. Within those species that have the pigments to begin with, sunny clear days and cool nights encourage the production of more red and purple pigments. A tree with adequate nutrition will have more basic material to work with to create pigment. Trees that are overwatered have damaged root hairs, so they've been unable to take up nutrients readily during the summer.

Davis residents: if you want to see these magical chemical reactions underway, head down West 8th Street and look for the Chinese pistache, or Stanford Place and Kent Drive to look for Ginkgo trees. Admire the golden yellow color on the Modesto ashes (Fraxinus) on L Streets and other parts of old East Davis. But we no longer recommend ash trees due to various disease and pest problems.

For vivid fall color in small spaces, plant Winged euonymus (Euonymus alatus 'Compacta'), an adaptable deciduous shrub with flame red fall foliage.

Trees for fall color in the Sacramento Valley:

Chinese pistache
Pistacia chinensis

    Most are grown from seed. Female trees have attractive red berries that attract song birds. Fall color varies from bright yellow to dark red. A male variety, Keith Davey, has reliable red fall color and no fruit, but availability is limited as it must be grafted.

Ginkgo, Maidenhair tree
Ginkgo biloba

    Varieties: just be sure to buy grafted male trees, as the fruit of the female tree smells like dog manure. And watch the young trees to make sure rootstock doesn't grow or you may end up with a female. Slow growers. Ginkgos are tough, reliable, and pest-free.

Acer rubrum hybrids; Acer x freemanii

    Varieties: Autumn Blaze is biggest, fastest. October Glory has a nice round form. Red Sunset is slower growing. All have red fall color, ranging from orange to dark red.

Pears, ornamental
Pyrus calleryana

    Varieties: Bradford is most common but has poor branch structure. Chanticleer, RedSpire, Trinity, Cleveland Select, Capital are all better, but all require careful pruning. Narrow, upright habit makes them suitable for side yards or small spaces. White flowers in spring. All have wine red fall color.

Tulip trees
Liriodendron tulipifera

    Oval-upright habit, nice yellow fall color, and interesting tulip-like flowers in the spring. Not spectacular, but attractive. Good examples on the streets near Emerson Junior High School in west Davis.

For pictures of fall color in and around Davis, click here

More plant chemistry in the landscape

We see a similar reaction in broad-leaved evergreens such as Star jasmine (Trachelospermum) and Japanese boxwood (Buxus japonica), whereby they discolor in the winter during cold weather. Cold soil reduces the availability of phosphorus (the roots can't take it up), and overwatering or saturated soil conditions reduce the uptake of it because roots are damaged. So the phosphorus moves into the stem, and the leaves manufacture some of the purple or red pigments. But no abscission layer is formed, so they don't drop.

This is not a problem, and normal color returns with warmer weather. This winter coloration is attractive in some of our landscape plants: the white variegated portions of Euonymus fortunei 'Emerald Gaiety' turn a pretty pink color in the winter, and Heavenly bamboo (Nandina domestica) varieties turn varying shades of red or purple.

Some trees go through the pigment process, but don't form an abscission layer. Turkey and Red oaks are good examples (Quercus shumardii and Q. rubra). First a red pigment forms, which is rather pretty. Then that red pigment breaks down, and the brown, dead leaves hang on until they are finally beaten off during winter storms or pushed off as new growth emerges in the spring. Needless to say, this greatly reduces their ornamental value.

Tuesday, September 29, 2009

How peppers spread around the world

The history of the spread and use of the plants of the genus Capsicum is a curious one. These plants, native to the Americas, are now grown throughout the world, and appear in recipes that come back to America in ethnic restaurants. The genus is represented in American cuisine by all of the varieties of green peppers, chili peppers, Oriental hot peppers, pimentos, and paprika. The amazing part of this is the speed with which the plants spread and were adopted into local cultures along the routes of the Spanish and Portuguese explorers of the 15th and 16th centuries.

Here's the history of how they spread in an article written by my father.

Monday, September 21, 2009

September means planning for winter fragrance!

September isn't really fall, is it?

Not here in the valley! It can be hot and dusty, which makes it hard for gardeners to look forward to the next season. But just as we plan in spring for our summer gardens, NOW is the time to plan and plant for your winter garden!

Good gardeners are always looking ahead to the next two seasons.
You're picking peppers and thinking about peas! The powerful scent of a summer gardenia reminds you that it's time to think about winter fragrance. For generations of gardeners, winter fragrance has meant sweet peas (Lathyrus) and stock (Matthiola). If you're frugal and like to plant from seed, September is when you plant both of these. (You can also do a planting of sweet peas in February and hope that we don't get hot earlier than usual).

When I was a young teen, working around the neighborhood, I worked for one afternoon for a plant breeder who also happened to be an excellent and rather particular gardener. He hired me to dig a trench a foot deep, setting aside the soil; then I dug compost and manure into the next foot of soil, and planted sweet pea seeds in the bottom of the trench. I blended compost and manure with the first soil and set it aside, as he planned to layer it in over the plants as the vines grew. Sure seemed like a lot of work (which, of course, is why he was paying me to do it!).

Years later this technique became popular with organic gardeners in areas of poor soils and was called double digging. I call it aerobic gardening. I thought I must have done it right, because years later he complimented me on the quality of the sweet peas that year. But I now know that a lot of it was luck-- mild weather when the vines are flowering--and some of it was knowing which varieties to plant. Not to mention knowing how to tell a 14-year-old boy how to do a task correctly! I'm still working on this last concept....

Sweet peas like a mild climate, and especially dislike hot weather.
We plant them here so they're established enough to get through the winter and bloom before hot weather hits. Our winters are rarely cold enough to damage the plants, although they were killed or severely damaged in the severe freezes of 1990 and 1998. Sweet peas need full sun in the winter--watch the sun pattern as it shifts to the south to make sure they won't be in the shade in February and March. They prefer soil that has been amended (see above!) so it drains well in the winter. There are even dwarf varieties that can be grown in pots.

The names of the different types of sweet peas can be a little confusing.
Older varieties are usually called "heirlooms." Modern varieties are called Spring-flowering and Summer-flowering, but none of them really flower in the summer here. These types start blooming when daylength is increasing in mid-spring, and flower from mid-April through May until temperatures reach the mid-90's. Early-flowering varieties will bloom earlier in the winter if you plant them early enough (i.e., NOW!), but are less heat-tolerant.

The older varieties are remarkable for their fragrance and have become available again from specialty seed suppliers. Several seed companies now offer the older varieties.

I said that none of the regular sweet peas bloom in the summer here, but folks driving through Gold Country and other parts of Northern California have probably noticed the two-toned perennial sweet pea (Lathyrus latifolius) that has naturalized in those areas. This one is different: it blooms in the summer and tolerates aridity, but isn't especially fragrant.

Stock is like deer: the name is singular and plural at the same time. This is one of our best winter annuals.
I have no idea what the common name comes from, and a quick search of reference books and on the internet didn't elucidate. The Sunset Western Garden Book describes some as being "branching" (multiple shoots from the base) and others as being "unbranched." Our experience is that early planting (i.e., NOW!) will give you plants that branch from the base, and late planting will give a single spike of flowers. The flowers have a great sweet/spicy fragrance. Like sweet peas, you don't just stick these in the ground in heavy soil areas: turn compost into the whole area before you plant.

I have an old memory of stock...another good gardener in that same neighborhood where I grew up: a wonderful woman who let me plant whatever I wanted in her yard, as long as she could cut or smell the flowers. She planted intensely fragrant stock just under the window where the breeze came in. Years later I smelled the stock we sell as bedding plants and got a hint of that sweet and spicy fragrance, but I realized that she had planted a different species (M. longipetala bicornis) known as the Evening-scented stock. Unfortunately, this stock is not common in the trade.

Nevertheless, the stock that you plant from seed or six-packs will have some of that same special scent. Plant it in full winter sun. The more dwarf varieties aren't as fragrant, but can be crowded into small pots for winter color. Although we sell it as a winter annual, many gardeners report stock living through the summer and reblooming, and it occasionally naturalizes by reseeding, gradually reverting to taller, single-flowered types.

There are other seeds to plant in September.
Snapdragons, calendulas, pansies and violas are popular winter and spring-blooming annuals that can be grown from seed or transplanted from seedling packs.

Wildflower seeds are planted now for late winter and spring bloom--California poppies are the best known, but Lupines, Tidytips, and many others grow and naturalize well here. You can't just fling these seeds onto hard, dry soil: loosen it first by tilling or scratching the surface. Cover the seed with a fine layer of compost, and water daily for a few weeks until winter rains begin.

Many perennials can be grown from seed or transplants now for blooms next year. And vegetable growers are already planning their winter gardens, planting broccoli, cauliflower, cabbage, peas, carrots, beets, and more.

Save money and spice up your winter garden by planting now from seed!

(originally written for the Davis Enterprise, August 23, 2001)

Sunday, September 13, 2009

September in your garden!

September in your garden!

Lawn: Fertilize lawn with a regular lawn fertilizer. Apply pre-emergent to prevent winter weeds, or renovate if heat breaks— de-thatch, aerate, overseed.

Roses: Fertilize mid September to early October to get a great fall bloom.

Trees: Fertilize deciduous trees.

Shrubs: Prune evergreen shrubs when heat breaks. Plant landscape shrubs, trees, and ground covers. Move existing landscape plants.

Annuals: Start seeds or buy plants of pansies, violas, snapdragons, Calendula, stock, sweet alyssum, and more. Broadcast wildflower seeds.

Perennials: Lots of perennials can be started from seed this month: foxgloves, candytuft, columbine, coral bells, Dianthus, and many more. Preemergents or mulches will help prevent annual winter weeds. Cut back herbaceous (soft) perennials hard; lightly trim woody ones. Best time for a major cleanup in the perennial border. Plant bulbs when soil has cooled.

Vegetables: Plant broccoli, cauliflower, carrots, lettuce, greens, peas, beets, onions, and more.

Weather notes: Hot, dusty, windy. Wash plant foliage early in the day to remove dust and insects. Move indoor/outdoor plants back in by Hallowe'en. First cold rain usually mid-late October, but don't count on it....

Watering systems: Set timer for fall schedule late this month.

Pests and diseases: Whiteflies, leafhoppers, spider mites.

Shop now for: Perennials in small packs and pots; spring-blooming flower bulbs; landscape plants.

Thursday, August 27, 2009

We get questions....

Dear Don,

I need suggestions for a difficult shady planting area off our parking lot. We planted Mondo grass in this area years ago and it is doing well, but it is very slow and not very interesting. It is the north side of a commercial building, and is also shaded by Sapium trees and very large Xylosma shrubs (which we keep pruned up for safety reasons). Watering is with an old sprinkler system with regular lawn-type heads.

It would be nice to get some flowers, but that might be asking a bit much. We’re ok with keeping the mondo grass, just want something more interesting with it. -- Bob


First, review the sprinklers for coverage and make sure the entire planting area is getting watered.

Lift several clumps of mondo grass and plant most of them in the shadiest areas. Set some in reserve to plant around new plants.

Plant groups of 3 – 5 each of one-gallon perennials in 5 - 6 places. Choose for tolerance of shade, some seasonal bloom if possible, and ability to withstand existing water schedule and raking of leaves in fall.


Turf lily

Liriope muscari

Purple flowers in summer, grassy leaves. Long-lived, very shade-tolerant.

Lenten rose

Helleborus orientalis

Flowers in pink, purple, or white resemble single rose blossoms. Bloom in winter. Very shade-tolerant, tough, long-lived.

Heartleaf bergenia

Bergenia cordifolia

Big leaves look lush year-around. Pink flowers on the common form are a nice bonus in late winter. New white-flowered form (‘Bressingham White’) is even showier, and the two colors mix nicely.


Aquilegia hybrids

Showy flowers in spring. Each plant lives 3 – 4 years, but tend to reseed nicely. Attract hummingbirds.

Coral bells and ornamental Heucheras

Heuchera sanguinea and hybrids

Delicate-looking wands of pink-red flowers in spring; hybrids are grown for colorful foliage.

You may want to add some low shrubs along corners or up against the building.

Plants selected should be no more than 3’ tall, or readily pruned to that height. Examples: dwarf Heavenly bamboo (Nandina domestica ‘Firepower’) could be planted on 2 – 3’ centers (a total of 10 – 12 plants). Other options include Sweet Victorian box (Sarcococca ruscifolia) or a dwarf variety of Oregon grape (Mahonia aquifolium).

Sunday, August 23, 2009

Early Autumn Flowers

Early autumn flowers!

Sure feels like fall today, with high temperatures in the mid-80's. There will be hot weather again before summer ends, but gardeners can look ahead now to one of our best gardening seasons....

Warm days, cool nights, and dry weather characterize the early fall here. Great gardening weather, a perfect time to re-seed your lawn, plant landscape shrubs and trees, divide perennials. But don't forget flowers at this time of year.


    Nurseries and garden centers are already carrying the winter annuals, many of them in full bloom: pansies and violas, snapdragons, stock, and calendulas in six-packs and four-inch pots. These will give quick color, but may go out of bloom if there is another spell of hot weather. Don't be discouraged. Trim off the spent blossoms and seed heads, and new flower buds will emerge almost immediately. All of the afore-mentioned flowers will bloom all winter and well into next spring. One of my favorites is Chrysanthemum paludosum. This relative of the more familiar Mums has an annual white flower that resembles a miniature Shasta daisy, blooming from October through May.


    Perennials bloom year after year. Many summer bloomers produce another crop of blossoms in fall; others are autumn specialists.

    Yarrow. Many new colors, mostly warm pinks, reds, yellow. All yarrows draw beneficial insects and spread steadily but not rampantly. Will take light shade. These have been blooming all summer, but usually put on a late summer surge of flowers which age gracefully and which also dry nicely.

    Asters resemble Chrysanthemums, but bloom earlier: mid-summer to early fall. They are bright little daisies, available in lavender, purple, pink, red, and white. All attract butterflies. New varieties have compact growth habit. One of my favorite garden plants in recent years is the old-fashioned fence aster, a big sprawling lavender-flowered daisy which sprawls out over nearby shrubs and trees in September and October.

    This is the fall perennial that everyone knows. The big-flowered types that you see in stores are not great garden plants. They require careful staking, pinching, and trimming to get large flowers, and the plants flop all over the place. But there are many miniature, smaller-flowered varieties whose compact growth habits make them excellent garden plants. King's Mums in Clements is the authority on Mum varieties and cultivation:

    Sedum spectabile
    Sedums are succulent plants, usually grown for the foliage. But S. spectabile has spectacular early fall flower clusters in shades of pink and red, which age to a unique brownish-red color. This is a tough plant for full sun or light shade.


Fall in the Sacramento Valley is a wonderful season for our roses. On your traditional types such as Hybrid Teas (long-stem cutting roses), trim off the hips (seed pods) that may have formed this summer. Shape the bushes a bit with light pruning. Remove any suckers that have sprouted – they are obvious shoots, much more vigorous and vine-like than the main plant. Wash the summer dust and spider mites off the foliage with a strong blast of water. Give each plant some fertilizer and a good soaking. You can expect a nice crop of flowers by Hallowe'en, with blossoms continuing into November.

More informal roses such as the shrub and landscape types may have set a large crop of hips, and these color nicely as the nights get cooler. Rose hips can be used for tea (simply remove the seeds, then simmer 4 – 6 hips in 2 cups of water for about 30 minutes, strain and serve) or for winter wreaths and decorations.

Salvia: the sages are the royalty of the autumn border.

With over a hundred species and varieties of Salvia available from growers, we have types that bloom nearly any time of year. But summer and fall are when Salvias really fill the border. Vivid purples, reds, pinks, some startlingly bright. Salvia flowers attract hummingbirds. Here is just a sampling of some notable species and hybrids.

    Annual salvias
    The short, annual red-flowered S. splendens blooms until frost. S. farinacea, the Texas violet, has lovely light blue flower spikes. It doesn't usually overwinter here, so we treat it as an annual. Though both are considered 'summer annuals', their fall bloom is outstanding.

Perennial salvias
Herbaceous (soft) forms that are especially showy include

    S. elegans
    Pineapple sage, named for the scent of the foliage. Blooms into winter. Expect some cold damage, but it usually resprouts in spring.

    S. guaranitica
    Anise-scented sage. Big sprawly thing with spectacular flowers. Spreads. Hack it to the ground each winter.

    S. 'Indigo Spires'
    Another sprawly plant with vivid violet-blue flower spikes which are long enough to cut for flower arrangements.

    S. nemorosa
    One of the showiest garden Salvias, with a low growth habit and copious blooms. 'East Friesland' is one of the best varieties: non-stop spikes of purple flowers from May through October.

    S. uliginosa
    Bog sage. One of my favorites for the sky-blue flowers. As the name implies, this will grow in soggy soil. In the 'normal' border it makes a great indicator plant: droops when the border needs water, then perks back up instantly. Be forewarned: spreads aggressively. Prune with a machete.

Shrubby salvias

Forms that have showy summer and fall flowers include:

    S. greggii
    with numerous varieties and hybrids.Called Autumn sage, although they will bloom nearly any month of the year here. Steady, reliable, long-lived shrubs with flowers that are small but abundant and available in nearly every shade of red, purple, pink, and even white. S. microphyllais basically the same, and S. x jamensisis the name given to hybrids between the two species.

    S. leucantha
    Mexican sage. Big, upright to about 4' here, this may fall over as it blooms. So plant it behind other, stouter Salvias or lower shrubs. Spectacular velvety royal purple flowers continue until frost. One of my favorites.

There are several attractive native and culinary Salvias as well.

These California natives are great garden plants, especially in low-water landscapes. But most bloom in spring or early summer, finishing their cycle before our summer heat and drought puts them into a semi-dormant state. Attractive foliage and growth habit makes them suitable background plants for the fall-blooming species.

    S. apiana
    White sage, used for burning rituals. Intensely scented foliage is silvery-gray, almost white. Great in a moonlight garden.

    S. clevelandii
    California blue sage. A chaparral shrub from Southern California. There are some named hybrids with uniformly compact growth habit, showier flowers than the species.

    S. spathacea
    Pitcher sage. The giant arrow-shaped leaves are attractive enough in their own right. The 3' flower spikes are stunning and, as Sunset says, 'a magnet for hummingbirds.' This spring bloomer may give a repeat fall bloom.

    Salvia officinalis
    Garden sage. This is the sage we use in cooking, but it is also an attractive shrub in the landscape or border. The standard form has purplish-grey leaves, but there are forms with golden and pink variegation as well. Tolerant of heat, drought, light shade, it grows to about 3' x 3' or more. Combine with lavender and rosemary as the year-'round backbone of your herb garden.

Brightening the autumn flower garden can seem like a challenge, as we continue to swing back and forth between cool weather and hot spells. Don't worry about short intervals of hot weather. Water new plants thoroughly when you install them, then check every other day. As the days shorten and nights cool, new transplants probably need water every 3 – 4 days.

From the Davis Enterprise, September 27, 2007

Tuesday, August 18, 2009

Cool gardens on a hot day

Cool gardens on a hot day: visiting the UC Davis Arboretum Terrace Garden and Carolee Shields Garden.

Sunday, August 16, 2009

August in your garden and landscape

Here are some ideas for August garden activities. Check out the printable monthly calendar and list of 'what's blooming in August'.

Welcome to the Redwood Barn Nursery blog!

This is a place for seasonal garden tips, links to special articles at the Redwood Barn website, other interesting garden-related articles and sites, and your questions and comments.