USING PLANTS THAT CAN TAKE THE HEAT.

Byline: Joshua Siskin

The experienced Valley gardener seeks out plants that bloom like crazy year after year, are water thrifty and require nothing more than an occasional pruning to keep them in bounds.

A handful of such plants, all of them robust shrubs of medium stature, are blooming now. At the top of the list would be African hibiscus (Anisodontea hypomandarum). This is a shrub that, at its mature height and girth of 5 to 6 feet, has no fewer than 1,000 flowers open at any given moment. The flowers are salmon pink, about 1 inch across and resemble miniature hollyhocks.

Blue hibiscus (Alyogyne huegelii) is a relative of the species mentioned above and is laden with silky lavender flowers from late winter to midspring and at other odd moments as well. The decorative leaves of blue hibiscus are palmate, deeply lobed and appear to be the hybrid offspring of an oak leaf and a snowflake. Blue hibiscus has a tendency to put out lanky shoots which, if nipped before they grow too long, will gladly stay within the confines of a pleasing, nearly spherical form.

Another plant on the list of heavy and reliable bloomers would be spider flower (Grevillea species). The flowers on grevillea shrubs do indeed resemble spiders, albeit in various shades of bright red and pink. Grevilleas, which find water and fertilizer equally loathsome, are consistently victimized by too much coddling. It is as though their leaves, as prickly as juniper scales, are meant to serve as a ``hands off!'' warning when it comes to caring for grevilleas in the garden.

Soil preparation for all of these shrubs should be the same. Amend soil with enough compost to eliminate compaction or any other drainage problems. Dig a hole twice the diameter and the same depth as the root ball of the shrub you are about to plant. The soil should drain well to a depth of at least one foot below the bottom of the planting hole.

There are parts of the West Valley, Simi Valley and Thousand Oaks where the soil is extremely heavy and poorly drained. In such cases, there is no choice but to break it up with a pick and mattock; if you are not at the peak of physical fitness, it might be wise to hire a neighborhood gardener to do this job.

Another wonderful perennial flowering now is the Marguerite daisy (Chrysanthemum frutescens). Although not as long-lived as the woody shrubs mentioned above - count on two or three productive years - the Marguerite daisy is without peer in the denseness of its bloom. Its lacy foliage is virtually blocked from view on account of the blanket of white, pink or sulfur-yellow daisies that spread themselves over the plant as the Los Angeles winter merges seamlessly into spring. The Marguerite daisy also differs from tougher shrubs in requiring a regular watering regime.

In the Valley, it is a good idea to give any flowering shrub - including those advertised as drought tolerant - some protection from summer sun. Even if you plant now, take into account how much sun the plant will receive in July, August and September. A good half day of the Valley's summer sun will be more than enough to bring out the best in any flowering plant - from rose to rudbeckia to rosemary.

Clyde Huffman of West Hills regularly tills horse manure into his adobe clay soil during the rainy season and inquired, by e-mail, as to whether this practice is truly beneficial to garden plants. Certainly, over a period of years, this sort of soil conditioning will have positive results. Soil tilth will improve and plants will thrive in it. However, before tilling it into the soil, you can significantly increase the value of horse manure by composting it with straw and worms. Straw allows oxygen into the rotting manure, encouraging aerobic, humus-forming bacteria to proliferate in it. A few handfuls of red wriggler worms - the kind you use for fish bait - will also speed up decomposition and composting of the manure.