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

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 www.hydrangeashydrangeas.com.

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

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 (http://www.ecke.com) 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!

Poisonous?
NO!
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.
They're NOT POISONOUS!

From snopes.com:
"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.

Poisonous?
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.

Poisonous?
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.

Poisonous?
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.

Poisonous?
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.

Poisonous?
No!

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.

Poisonous?
"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.

Poisonous?
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 -- http://www.calpoison.org -- for more information about poisonous plants.

Enjoy your holiday plants -- carefully!

Published in the Davis Enterprise, 28 December 2000

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

Begonias

Bougainvillea (older plants likely to recover)

Hibiscus (tropical)

Mandevilla (evergreen types)

Serious damage, but likely to resprout:

Avocadoes

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).

Lantana

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.

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