GARDENING : FOR VALLEY GARDENERS IT MIGHT AS WELL BE SPRING.

Byline: Joshua Siskin

Spring is sooner recognized by plants than by people, the Chinese proverb goes.

Unless, you could add, those people live in Southern California. By February, if not sooner, gardeners already are digging and planting while their counterparts across the country can only dream.

Two circumstances may give the Valley gardener pause when looking toward the best time to plant. The first is the continuing possibility of cold nights, and the second is the distinct chance of more rain.

Until March 15, cold nights here are a reason to delay planting of subtropical vegetables such as tomatoes and eggplants and to hold back on putting in impatiens and begonias, which could turn to mush if the temperature dips to 32 degrees. Last year, for example, we experienced a rare late frost toward the end of February.

Rain is not uncommon in March, and heavy rain can wash away newly planted seeds in a vegetable garden. Rain also can damage small-size impatiens and begonias planted from six-packs or 4-inch pots, whose succulent leaves and stems may be broken by pelting precipitation.

The potentially damaging effects of late cold and rain may be mitigated by raised beds that, in any kind of weather, provide the ideal environment for growing plants. Vegetable plots, flower gardens and perennial borders all may be planted in raised beds. The soil in a raised bed is fluffier, more porous and more oxygenated than regular soil, thus it absorbs more heat during the day, releasing it back into the air surrounding your plants at night. A raised bed also drains better than regular soil and is less susceptible to erosion, allowing rainwater to drain through and not wash away seeds.

Making the bed

To build a raised bed, remove the top 10 inches of soil. With a spading fork plunged into the earth, loosen bottom soil to a depth of 20 inches. As you loosen this soil with a back-and-forth movement of the fork, you will see the earth fluff up. The spading fork has added oxygen to the soil, increasing its volume. Now add amendments to the 10 inches of excavated soil lying on the surface. Use finished compost, leaf mold, peat moss, nitrohumus or whatever decomposed organic material you can lay your hands on; mix in at least 12 cubic feet of amendments per 100 square feet of raised beds. Upon returning the top 10 inches of amended soil, you will have a bed that is raised several inches above ground level. You can use any basic fertilizer (Kellogg's All-Purpose or one of the Gro-Power products) at the rate of two pounds (which will fill one average-size coffee can) per 100 square feet. If you want to go strictly organic, fertilize with blood meal, hoof and horn meal or cottonseed meal. Grade the bed with a bow rake and you are ready to plant.

Building raised beds for your plants is like spending most of the hours of each day with your children. Both are time-consuming and tiring endeavors, yet both represent the ultimate in upbringing. Besides, why have plants or kids in the first place if they're not going to get the best preparation for life? Most people don't build raised beds and most people don't spend most of the day with their kids; as a result, what happens to plants and to kids is entirely unpredictable.

Some of the more unusual, recently available varieties of plants will do especially well in raised beds. These included an azalea cultivar with maroon leaves known as ``Little John.'' This azalea will produce a few red flowers, but is grown principally for its foliage, which grows dense and lush on a plant that may reach a height of 6 feet or more.

Sunny delight 

A shrub that is beginning to appear wherever azaleas are grown and even sunnier locations is Loropetalum chinense, especially its red-leaved cultivar known as ``Razzleberri,'' ``Rubrum'' or ``Plum Delight.'' I first saw Loropetalum mass-planted as a low, informal hedge outside the main office of Monrovia Nursery in Azusa. There, it gets morning sun, and its fringed and mildly fragrant flowers are prolific. Loropetalum survives freezing weather and left unpruned will grow to more than 20 feet tall.

A plant that never requires pruning because of its well-spaced arching branches, but may be pruned frequently to create a compact form, is the sweet pea shrub, Polygala dalmaisiana. The flowers of the sweet pea shrub are rosy mauve and have a remarkable resemblance to those of the vining sweet pea, even though these plants are completely unrelated. The sweet pea shrub next to my front door has just begun to flower and should continue to do so until the end of summer.

Two sun-loving shrubs that should be more widely planted, and undoubtedly will be soon, are Geraldton waxflower and Canary Island lavender. The Geraldton waxflower, Chamelacucium uncinatum, blooms this time of year. It is botanically related to the New Zealand tea tree (Leptospermum scoparium) and bears a superficial resemblance to it. However, the flowers of Chamelaucium are somewhat larger, and it is also freer in form than the New Zealand tea tree.

Like all lavenders, the Canary Island species (Lavandula multifida), flowers on and off throughout the year. Unlike the English, French and Spanish lavenders, which have thin, small fingers for leaves, the foliage of the Canary Island lavender is as lacy as a Dusty Miller's. Grow it and the Geraldton waxflower in fast-draining soil in the sunniest garden spot you can find.

Two brand-new plants are the bird-of-paradise ``Gold Crest,'' which has yellow instead of the customary orange plumes, and from Australia, ``Mini-Ha-Ha'' Hardenbergia, a dwarf shrub.

Only the best

If you are looking for tools to get started, as in a shovel, spade and spading fork, consider value over price. You can spend $20 for what passes as a quality spade at a discount hardware store, only to have it break when you encounter a patch of compact or clay-rich soil. Snob appeal notwithstanding, Smith and Hawken is a company that provides tools that, used around the house, have been known to last a lifetime. Smith and Hawken's Classic English Garden Tools, available in their Pasadena store, may cost three times what you will pay for less-expensive tools elsewhere, but they also may be the last tools you ever buy.

CAPTION(S):

5 Photos

Photo: (1--Cover--Color) It's spring,

you dig?

(2--Color) Like all lavenders, the Canary Island species (Lavandula multifida) flowers on and off throughout the year.

(3--Color) A shrub that is beginning to appear wherever azaleas are grown is Loropetalum chinense, especially its red-leaved cultivar known by various names, including ``Plum Delight.''

(4--Color) Some unusual plants that do especially well in raised beds include an azalea cultivar with maroon leaves known as ``Little John.''

(5--Color) A plant that never requires pruning because of its well-spaced arching branches, but may be pruned frequently to create a compact form, is the sweet pea shrub, Polygala dalmaisiana.

Bob Halvorsen/Daily News