GARDENING : LOW-LIGHT GARDENS CAN BEGIN BLOOMING WITH BEGONIAS.

Byline: Joshua Siskin

One of the questions I am most frequently asked is what plant will bloom for a long time in low light.

In Los Angeles, the plant that blooms longer in less light than any other is Begonia x Richmondensis. It has pink flowers and scalloped, bronze green leaves.

(The ``x'' means it's a hybrid. As would befit a plant of such rare capacity, this hybrid's x-factor is twofold, since its parents are unknown.)

Yes, this begonia blooms longer than impatiens. In fact, it blooms in locations in which it is too dark for impatiens to flower.

The Richmondensis begonia flowers as long as it lives, which can be three or four years. Just plant it in well-drained soil and let it grow. Once established, however, it should not be watered more than once a week. If you water more than this, you will decrease its flowering and its longevity. It does not require fertilization. You may want to pinch it back occasionally since, unchecked, it may grow to a height of 3 feet. It may well be, however, that pruning and fertilization, which are invigorating yet enervating practices, take their toll on this plant and, if done to excess, result in an abbreviated life span.

But guess what. This same plant can also, like common bedding begonias, take a certain amount of direct sun, although such an exposure, since it requires more water, will also shorten the begonia's life.

The Richmondensis begonia also grows well in containers. Try planting several in a large pot - of say 16 inches diameter - so that you do not have to water more than once a week.

Speaking of container plants that never stop flowering, consider the chenille plant (Acalypha hispida), a species that could have been mentioned in last week's column on the spurge family, since it is a member of that group. The chenille plant gets its name from the wooly consistency of its hanging red flowers, which look like small spools of yarn.

The chenille plant should be grown on a patio or next to a wall because of its sensitivity to cold weather. It has been known to grow more than 15 feet tall, a size that would require patience to achieve, due to the chenille's slow rate of growth and floppy stature.

If you are in search of an interesting look for a shade garden, but despair of finding a selection of low-light, flowering plants, you might want to consider plants with variegated green and white leaves, many of which prefer a shady exposure.

Whether it appears in leaf or in flower, white is always noticed in the shade. Especially at dusk, when there is but little light in the sky, white makes its glowing presence known - by means of contrast - in dark corners.

The many cultivars of dead nettle (Lamium maculatum) are the ground covers of choice for shady situations. Dead nettles have triangular olive green leaves with distinctive white patterns. Depending on the cultivar, the leaves may have white stripes or white ink blots or white margins; alternatively, the leaves may be virtually white, except for green margins. Dead nettles have white, pink or yellow flowers, although these blooms are really an afterthought to the luminescent, variegated leaves.

Liriope spicata ``Silver Dragon'' is a clumping ground cover with green and white striped lanceolate leaves. Like all liriopes, it grows with a paucity of light. This one is something of a dwarf, staying below 1 foot tall.

The shrub you will want to include in this collection of low-light plants is Hydrangea macrophylla ``Variegata.'' It's a lace cap hydrangea whose influorescence consists of small white flowers surrounded by larger pink ones; its leaves are streaked in light green, dark green and white. Like all hydrangeas, this one should be planted in a hole filled with peat moss. Don't mulch too close to hydrangeas unless you want slugs - which hide in mulch - to eat holes in their leaves.

Tip of the week: The bougainvillea has fragile roots and, if carelessly planted, may die. When planting bougainvillea, cut the bottom off the container it's been growing in, but plant with the sides of the container intact. In a month or two, after lots of new growth is evident, cut away the rest of the container. By the way, bougainvillea may be pronounced either ``boogunvilya'' or ``boogunveeya.'' According to Webster, both pronunciations are acceptable.