IN THE GARDEN SILK TREES IDEAL FOR SPEEDY GROWTH IN SMALL YARDS.

Byline: JOSHUA SISKIN

Once in awhile, certain plants and trees practically jump out at you, more glorious than you ever imagined them to be. They stand out as though transported from another place.

During the last few days, I have been marveling at silk trees in full bloom. Normally, silk trees do not flower until midsummer, but this year they are already at their floral peak. If you grew up in Georgia or some other Southern state, you will remember this tree by its other name - mimosa. Its flowers are pink, wispy and, yes, silky too.

Until now, I had never seen a mature silk tree (Albizia julibrissin) that was more than 20 feet tall, but I saw a specimen the other day that was nearly 50 feet tall and the picture of health. The silk tree, a legume that manufactures its own nitrogen and really does not require fertilization, is advertised as a quick-growing shade tree that reaches a modest, mature height - exactly what homeowners with small yards often seek. The downside of the silk tree is its relatively short life span of 20 to 30 years.

In order to lengthen the life span of a silk tree, keep its soil on the dry side. The spectacular specimen I saw the other day was growing on the side of a hill between Santa Clarita and Sylmar, and I doubt it had ever been watered except by winter rain.

Another ornamental shade tree that grows rapidly to a moderate height is the chitalpa. It has pink trumpet flowers from spring to fall and a small water requirement. The chitalpa's rapid growth invariably creates a top- heavy tree; it should be pruned frequently during its first few growing seasons.

Q: I planted a jacaranda tree 10 years ago halfway between the house and the sidewalk. Since then, it has grown steadily but produces no more than six blossoms per season and blooms three weeks later than others in the area. Each year, I threaten to prune the tree. But in fear that I will kill it, I procrastinate another year. Is there a guide to pruning a jacaranda tree?

- John Meyer,

Woodland Hills

A: It sounds like your jacaranda may not be getting enough light. Plants bloom in response to hours of sun and/or heat exposure, and if your tree is shaded, it will take longer for it to accumulate its needed quantity of such hours. Jacarandas go through a brief period of leaflessness in late winter or early spring. It would make sense to prune them just after they bloom in order to maximize their flower display.

TIP OF THE WEEK: For years of summer color, plant dahlias, available now as bedding plants at the nursery. Their multilayered blooms, resembling small hybrid tea roses, stand out in yellow, orange, red and violet. When dahlias die back to the ground in the fall, cut off their dried leaves and stems, but do not extract their bulbs. Next spring they will come back bigger.