GARDENING\Many put simple, thrifty jade on succulent pedestal.

Byline: Joshua Siskin

Every plant has its moment, and for the jade plant, that moment is now. In January, it produces cymes of white flowers with a tint of rose to lighten up a dark winter's day.

This is enough, perhaps, to redeem the jade plant in the eyes of those Angelenos who consider its staid, porcelain appearance sufficient disqualification for use in the garden.

In New York City, just about everyone has a little jade plant in a tiny pot sitting on the window sill. Through piercing winter cold and dripping summer humidity, people in northern climes long for the dry desert heat that the jade plant evokes.

Something else makes the jade plant irresistible to New Yorkers. The jade is a paradigm of simplicity and thrift in plant construction. Glabrous green leaves are attached to brown stems - and that's it. Kept in a small pot, a jade plant will barely grow from year to year. It must be reassuring in a metropolis of pomp and opulence, of complexity and frenzy, of decay and decadence, to come home to the unadorned, clean-living, placid, predictable jade plant.

Like the vast majority of smooth-leaved succulents, the jade plant (Crassula argentea) comes from South Africa. It goes dormant in summer and does not require much water at any time as long as it is kept out of the hot sun. It is a classic plant for Southern California and will grow well anywhere from Palm Springs to Valencia. In the Antelope Valley, however, it runs the risk of cold damage.

Crassulas are closely related to sedums, cotyledons, and sempervivums, all of which are in the orpine family (Crassulaceae). Other kin include aeoniums, kalanchoes, dudleyas and echeverias.

All people belong to one of two groups: those who like succulent plants and those who dislike them. Succulents are especially popular among beginning gardeners because they are easy to grow and to propagate. Succulents are designed for people with little time or money to care for plants, or for those with an appreciation for sculpture, of which jade and other succulents are living examples. People who don't like succulents complain that they grow too slowly, that their bloom time is too short, that there is nothing lush or dynamic about them. Veteran gardeners often are uninterested in plants, such as succulents, that are not a terrible challenge to grow.

Yet one thing is for sure: Until you have seen massive succulent displays, such as those at the Huntington Botanical Garden in San Marino, you have no right to pass judgment on these plants. In the San Fernando Valley, you can acquaint yourself with them at California Nursery Specialties, at 19420 Saticoy St., just west of Tampa Avenue. This unique nursery is open to the public on weekends only.

The jade plant, like many other succulents, opens its stomata at night, while other plants open theirs during the day. Stomata are leaf pores that admit carbon dioxide, used by plants for making food. It is important to remember that plants make their own food, which is sugar, out of carbon dioxide from the air and water from the soil. People talk about "feeding" their plants with "plant food." Actually, the food they refer to is just fertilizer, which is made up of mineral compounds that, taken up into the plant, make it possible for photosynthesis - the synthesis of carbon dioxide and water to make sugar - to take place. In any event, succulents such as the jade plant take their carbon dioxide in during the night to minimize water loss. This nighttime stomatal opening - in addition to leathery leaves - allows succulents to conserve water in the arid climates they call home.

I have yet to find a better outdoor container plant than the jade. It does particularly well in open-to-the-sky, yet protected locations such as a balcony, exterior landing or atrium. It is truly low maintenance with subtle, yet lasting ornamental virtues. Variegated jades, whose leaves are streaked with yellow and pink, are also worthy container specimens.

Jade plants are propagated by breaking off pieces and sticking them in just about any kind of soil. You can detach two-foot long "mini-trees" and create respectable sized specimens overnight. Or, place single leaves - which will root without difficulty - in potting soil and start your own nursery of jade.

Tip:

There is one succulent plant that blooms - or at least produces colored bracts that pass for flowers - 365 days a year. This is the crown of thorns, sold as Euphorbia milii or Euphorbia splendens. South of the Sepulveda pass, it grows in full sun, while in the San Fernando Valley it requires some shade to perform as advertised. It makes a fiery, breathtaking low hedge.