Wednesday, July 4, 2012

Succulents and Cactus!

Succulents have always been in my life.

We were the only ones with a cactus garden in our front yard. My parents were way ahead of their time for a water-appropriate Southern California landscape. Actually, it is a succulent garden, including cactus. Some were fuzzy, some showy, and a few were really spiny. Lots of kids encountered the latter during neighborhood games of kick-the-can.

I vividly recall backing into the business end of a century plant's spine once. In the front my folks had planted 5 or 6 century plants (Agave americana) in the early 1950's. A couple of decades later these all flowered at once, with 30' spikes opening into giant candelabras of blooms wildly attractive to bees and hummingbirds. After flowering the main plant dies, creating a giant cleanup mess, though several new 'pups' have usually formed at the base to replace it. But we pulled out most of them at that point � with a Jeep and a chain.

Once that was all cleared out, my mother kept planting interesting succulents and cactus. Some of her plants came from my grandfather. With a greenhouse in Pasadena and a garden in Palm Springs, he was an ardent cactus collector who also dabbled in other succulents. One of my reference sources for this is The Cacti of the United States and Canada (Lyman Benson, 1982), which he gave me with great pride as he had provided several of the photographs to the author.

When mom turned 50, I gave her Jacobsen's Lexicon of Succulent Plants and she was off and running. Rekindling her interest, she began collecting and propagating. Then she discovered that local nurseries would buy flats of them. Additional greenhouse space was built on their suburban lot. She finally phased back the production part a couple of years ago. At one point she confided in me that The Manual had turned out to be her most significant birthday present. Flowers and candy? Ha!

So you'd think I'd have written about succulents and cactus by now, pretty much having been hard-wired for them. And suddenly succulents are popular again. It's easy to see why.

  • Interesting colors and textures.
  • Low water use. Replacing your lawn with Sedum spurium or Delosperma cooperi could save over 15,000 gallons of water a year (but you can't walk on it much).
  • Spectacular, sometimes bizarre flowers. Asclepiads trap pollinators in cage-like flowers. Stapeliads smell like rotten meat to attract flies for pollination.
  • Easy to grow. They can go weeks without water.
  • Ridiculously easy to propagate.

A stem stuck in dirt will grow, or often just a leaf. I remember my son watching his grandmother "sticking" cuttings, and he asked in wonder, "so I can just stick this in dirt, it'll grow roots, and someone will buy it?" Welcome to the nursery business, my boy.

They are slowly shedding their reputation as collectors' plants, or something gathering dust in a pot in grandma's garden. I am happy to see succulents moving out into the regular landscape, providing a foliar foil for grasses and Agapanthus, or providing little points of contrast among annual and perennial flowers.

Succulents are plants which store water in modified stems and leaves. It is an obvious adaptation to dry climates, and succulents are heavily distributed in the "horse latitudes:" the subtropical latitudes about 30 - 35 degrees north and south of the equator, where winds are light and the weather is relatively dry. Most of the world's great deserts are in the horse latitudes.

Since we're a little north of that latitude (at 38 degrees N), it is important to know which of the succulents are subtropical and need winter protection. Some well-known succulents need to come indoors before frost, or be grown in a protected microclimate:

Aloe vera:
    grown for the medicinal leaves. Other Aloes are hardy, but not this one.

Ceropegia linearis woodii (Rosary vine):
    heart-shaped leaves, strange fly-trapping flowers.

Crassula argentea (Jade plant):
    elegant container plant has several varieties.

    some with fuzzy leaves (Panda plant, Felt plant), others with showy flowers; all are tender.

Senecio rowleyanus (String of pearls)

To simplify: before Hallowe'en move the fuzzies inside and the jades to the porch. Cold is bad, but cold and wet is worse as they'll rot. A screened porch protected from rain is a great place for a collection of succulents.

Lots of unrelated types of plants are succulents. To answer a common question: the difference between succulents and cactus is that all cactus are succulents, but not all succulents are cactus. Cactus are all members of one family: Cactaceae. Other succulents come from many families, ranging from lily to cucumber. Many plants have stems or leaves which store water, but aren't considered part of this group. Impatiens and begonias have "succulent" (i.e., juicy) stems. But they lack the thick cuticle, or skin, that protects the plant from drying and enables a true succulent to withstand long periods without water. One oddity about succulents? They can store carbon dioxide to transpire at night, producing oxygen when most plants are producing CO2.

Popular succulents such as Hen-and-chicks (Echeveria) are leaf succulents:

    The leaves are thickened to store water, often coated with light-colored powder or hairs that provide protection from sun. Those without such natural protection are better in partial shade here. Flowers range from very showy (Kalanchoe blossfeldiana) to insignificant.

Cactus are stem succulents:

    The stem has a large amount of soft living tissue to store food and water, and very little woody tissue. Cactus don't have leaves (with some exceptions), they have spines clustered on areoles. In the wild they have shallow, wide-spreading root systems. Early botanists measured one young, 5-inch-tall Saguaro (Cereus gigantea) whose roots had spread over 15' in all directions, at only four inches depth!

The roots can form water-absorbing root hairs extremely quickly, then lie dormant for months until the next rainstorm. This enables them to sit in a pot in your garden for many years with only occasional care; I have a cactus that has been in the same pot for 40 years. Many cactus have spectacular flowers, and most have fleshy, juicy fruit. Prickly pear fruit is delicious, but the spines must be carefully removed first!

Cactus spines provide sun protection, along with the same kinds of powdery coatings and fine hairs found in other succulents. Old Man cactus has extra-long white hairs as well as spines. Again, if the variety you are buying has unprotected fleshy parts it may be best in partial shade here.

Day-blooming cactus often have very showy flowers in shades of pink, red, or yellow. Look for Echinocereus, Lobivia, Mammillaria, Rebutia and more. Night-blooming types, pollinated by moths, usually have white or pale yellow flowers, often very fragrant, on very large plants.

Succulents, including cactus, can be grown as houseplants. They require the brightest light you have, and some may lose their color or coating in low indoor light. Paler growth and stretching are signs the light is too low. The biggest risk is overwatering. For indoor growing, plant in a fast-draining potting soil, either one made specially for cactus, or by adding 1 part pumice or perlite to 3 parts regular potting soil. You can mix a bunch of interesting types together in a pot to grow as a living bouquet of foliage, removing any that get too big. Or take cuttings as the plants get tall.

On the other hand, if you're growing them in pots outdoors, here's a trick to reduce how often they need water. Add some clean topsoil to the mix at about the same proportion as the pumice. It will help retain moisture, so you can go weeks (or months?) between waterings and the plant will survive.

Cold-hardy succulents for our area (Sunset Zone 14, USDA Zone 9) include:

  • Aptenia cordifolia (Red apples): a vigorous ground cover with red blossoms.
  • Echeveria (Hen-and-chicks)
  • Graptopetalum: large pinkish leaves.
  • Sedum (Stonecrops): one of the most useful groups of ground covers.
  • Sempervivum (Houseleeks): like little hen-and-chicks, great in pots.

Agave, Aloe, Euphorbia, and Haworthia vary as to hardiness.

Cactus are all from the Americas (with one weird exception), and range from the tropics to very cold northern latitudes and high elevations. Most can live outside here if protected from rain during the winter, so keep them under an overhang in the winter. The combination of cold and wet can lead to rot. Christmas cactus are semi-tender, about as hardy as Jade plants.

Note to parents:

    some members of the genus Euphorbia have very irritating sap. Certain cactus contain toxins and hallucinogens. If your kid gets interested in cactus and other succulents, you may wish to monitor which species he or she collects.

There is an excellent collection of succulents open to the public right here in Davis, at the Botanical Conservatory at UC Davis. Visit for more information.

Caudiciforms are a weird group of water-storing plants that have woody enlarged stems (caudex), sometimes getting quite large. With age these can get very large and quite valuable.
Examples: Adenium obesum (Desert-rose), with oleander-like flowers (it is related, and also has poisonous sap like oleander).

Neither of these are true palms, despite the common names:

  • Beaucarnea recurvata (Ponytail palm)
  • Pachypodium lamerei (Madagascar palm)

Other caudiciforms have extra-large surface bulbs, from which new growth sprouts seasonally. People who get really serious about succulents and cactus tend to also collect caudiciforms because of the bizarre swollen stems.

Cresting, or fasciation, is a natural mutation of the growing point of a plant, occurring for unknown reasons in many types of plants. I've seen this flattened, distorted new growth on species ranging from fruit trees and roses to a hollyhock (the flower stalk flattened out, then split in two parts which coiled away from each other to create a Dr. Seuss mallow!). Because of the center-out growth habit of some cactus and euphorbias, this can cause interesting distortions. Which, of course, increases their value to collectors.

1 comment:

  1. Great info here. It's time to dispel the notion that cactus and succulent gardens always need to look stark and prickly!