IN THE GARDEN PERUVIAN LILIES - BLOOMING LOVELY.

Byline: JOSHUA SISKIN

The reason Valley gardeners appreciate rain is not only because it relieves our constant concern about getting sufficient water to our plants. Rain makes plants more attractive and healthy, giving them a glow and a vigor that is lacking during prolonged periods of drought. How pleasant to switch the sprinkler timer to the ``off'' position, knowing you will not have to water for some time.

I have been marveling at the silkiness of my Peruvian lilies since our recent three-day rain. The Peruvian lily (Alstroemeria) is one plant which, in my opinion, no Valley gardener should be without. Not only do Peruvian lilies flower over a long period of time, they make excellent cut flowers, and their azalealike blooms are famous for longevity in the vase.

Peruvian lilies are embarrassingly easy to grow. Although they prefer well-drained soil, they have a wide tolerance to soil types and may be given the same garden locations you would choose for daylilies (Hemerocallis), from full- to half-day sun, even if morning sun is probably the exposure they most prefer. Peruvian lilies require the same amount of water as annual flowers, which means they should be given a good soak every two or three days in warm weather. They make attractive plants in containers placed on patios or balconies that receive about four hours of direct sun each day.

Peruvian lilies can bloom at any time of the year. Their peak bloom period is from spring until fall. Colors include crimson, pink, rose, orchid, burgundy, purple, salmon, yellow and orange. Flowers may be damaged by thrips.

Yellow foliage on Peruvian lilies is a sign of mineral deficiency. To prevent this condition, fertilize two or three times a year with slow-release fertilizer. They also benefit from several inches of compost used as a mulch on top of the soil. This type of mulch keeps the soil cool, which will increase the number of flowers produced. If your Peruvian lilies are looking particularly peaked, you can simply prune them to the ground. Within a short time, fresh foliage will reappear from rhizomes, those underground stems with bulblike qualities.

To maximize Peruvian lily flower production, it is important not to snip the flower stalks with shears. Instead, twist the flower stalks off so that they detach in their entirety from their point of origin on the rhizome. This will hasten growth of more flowers.

If their predominant habitat had determined their name, Peruvian lilies would been called Chilean lilies, since Chile is the country that is home to the species we see in our gardens. Coming from Chile is an automatic recommendation where selection of plants for Valley gardens is concerned. The climate of Chile is remarkably similar to our own - a long dry season followed by moderate winter rains.

A ground cover that would grow well around Peruvian lilies is the carpet geranium (Geranium incanum) originating from South Africa, where the climate is also hot and dry in the summer and wet in the winter. Carpet geranium meets all the criteria of an ideal ground cover. It blooms from spring until fall, requires little water and has soft, lacy foliage. At the same time, it possesses a shallow root system and is not an invasive garden scourge like ground covers often turn out to be. The flowers of carpet geranium are flat, 1 inch in size and plum-colored.

TIP OF THE WEEK: One downside of the rain is that it postpones planting projects. Hold off on planting until the soil is no longer rain-saturated. At present, digging holes and backfilling them will only cause soil compaction, creating both a physical barrier to root growth and a deprivation of oxygen to the roots of your newly planted flowers, shrubs or trees. The growth of plant roots, like that of human beings, is critically dependent on a readily available supply of oxygen.