GARDENING : FLOWERING PLANTS FLOURISH IN HEAVY OR LIGHT GROUND.

Byline: Joshua Siskin

Like people who keep up their good spirits no matter where life takes them, plants with the greatest flowering capacity are not particular about the ground - or the soil - in which they are planted.

There are two basic soil types: sand and clay. Sand is described as coarse-textured - since its particles are gritty and visible to the naked eye - and light, since it is not weighed down with water. Clay, on the other hand, is called fine-textured - since its particles are of microscopic size - and heavy, since it easily gains weight with all the water it holds.

Some plants can grow in both types of soil. They will simply require more frequent watering when grown in sand then in clay.

A favorite group of plants for either sand or clay are the cupheas, all of which may be grown as colorful hedges. The most popular is false heather, Cuphea hyssopifolia, which makes a continuously flowering low hedge of 2 to 3 feet in height. It's usually seen with purple or pink flowers, but a white cultivar is also sometimes available. Cuphea ignea, known as the cigar plant, has 1-inch, orange firecracker blooms, and grows to a height of more than 4 feet. Cuphea micropetala has flowers that are similar to - but twice the size of - the cigar plant's; it may grow to over 6 feet tall. All the cupheas need a good shearing every now and then. Otherwise, they become leggy and stop flowering.

Another all-star for any kind of soil is the blue potato bush, Lycianthes rantoneii. This plant is really more than a bush. It can grow to over 10 feet tall but is completely nonplussed by topping, chopping back or any other indiscriminate pruning. It blooms nearly all the time in deep violet blue.

One of the blue potato's relatives is angel's trumpet, Brugmansia candida. Angel's trumpet produces large, pendulous, sweet-smelling trumpet flowers on and off throughout the year. Mostly, you will see them in white, but there is also a peachy pink and a yellow angel's trumpet that are occasionally encountered.

All of the above plants are currently flowering in the valleys around Los Angeles. The cupheas and the blue potato bush grow well in either full sun or partial shade; the angel's trumpet, on the other hand, should definitely be protected from summer's hottest sun.

Two lantanas that are blooming now appreciate the sun, but are not finicky about soil condition. One is violet and trails (Lantanas montevidensis); the other is a white hybrid that grows 2 to 3 feet tall. If you want the layered look of a low shrub and a ground cover, consider these two lantanas. If you wish to add a third, taller layer, plant Euryops pectinatus (Viridis) for vibrant yellow flowers that will contrast nicely with the violet and white lantanas.

Three shrubs in the mint family bloom nonstop in any kind of soil. Although they are considered Mediterranean-type plants, and therefore in need of well-drained soil, I have observed them grown in heavy soil without ill effect - as long as they are virtually ignored when it comes to the matter of water. The first is Mexican sage, Salvia leucantha, whose flowers are violet and white and whose leaves are pleasingly aromatic. The others would be rosemary and lavender. Rosemary will get root rot if grown in heavy soil and watered regularly. However, when denied summer watering, it will live well in heavy soil for years. There are half a dozen kinds of lavender, if not more, available these days. Plant them en masse for a carefree block of color and fragrance throughout the year.

Looking for a glorious perennial that blooms nonstop and self-sows in any soil? Your best bet is Gaillardia grandiflora, the blanket flower. This California native has sawtooth daisy flowers in yellow, orange, maroon and red.

Tip of the week: Do not work the soil when it is wet - you will compact it. This is a great time to buy seeds in packets and broadcast them over bare spots in the garden. In cool, wet weather, most seeds don't need to be dug into the ground in order to germinate. After broadcasting, cover them with a thin layer of peat moss or compost and keep moist until germination.