GARDENING : IT'S TIME TO PRUNE WHEN AZALEA, CAMELLIA FLOWERS FADE.

Byline: Joshua Siskin

Dorothy Adams of Burbank wrote me a letter, which she signed ``An old gardener.'' She has a question about pruning azaleas and camellias and one plaintive request: ``Tell us something we don't already know about gardening ... OK?'' In what follows, I will try my best to tell you something new.

First of all, however, I have to differ with the notion that you are an ``old gardener,'' for I have never met such a person. The idea of an ``old gardener'' is as ludicrous as that of an ``honest politician,'' or a ``poor Los Angeles Laker.''

Gardening keeps us young because it is an exercise in constant expectation, in looking forward to the future. We wait with baited breath for seeds to germinate and for flowers to bloom. We even wait for leaves to fall, a sign that the garden is temporarily at rest, invisibly recharging itself before beginning another cycle of life.

Adams wants to know what to do at the ``ebb side'' of the life cycle, when plants have stopped blooming. She is especially curious about the pruning of azaleas and camellias. Like all other ornamental evergreen flowering shrubs and trees, azaleas and camellias should be pruned as soon as they stop flowering. In this way, the plants can immediately start galvanizing their energy toward production of flower buds for the following year's crop. For example, sasanqua camellias - those with the single layer of petals and large yellow centers - are fall bloomers and should be pruned as soon as their flowers fade, which should happen within the next few weeks. The more common Japanese camellias - those that look like large roses - start blooming any time between now and spring, depending on the cultivar. Prune them also after their flowers fade.

Use a light touch in the pruning of azaleas and camellias. Because they are slow growers, radical pruning can set them back many years and depress their flowering. If plants have grown leggy, however, they can be cut back to encourage shrubbier growth.

With the continuous introduction of new plants into nurseries and thus into our gardens, questions arise as to how these unfamiliar species should be pruned.

How much to cut?

Here a word of caution is in order. Many drought-tolerant plants, despite the fact that some of them are rapid growers, should not be too heavily pruned, or they may go into decline. Examples of plants sensitive to overpruning include nearly all types of ceanothus and manzanita, as well as many species of grevillea, hakea and acacia. Even lavender, if pruned too severely, may come back with weak, spindly growth and then die.

Two popular drought-tolerant shrubs that can bloom at almost any time are the butter-yellow flowered Jerusalem sage (Phlomis fruticosa) and the vivid orange flowered lion's tail (Leonotis Leonurus). As a rule, with these two plants, each shoot should be cut back when it stops flowering. Additionally, every other year or so, these plants should be cut back to within 6 inches of the ground. If you forget to do this, the presence of mealybugs - those sticky white insects, sometimes stuck together in a cottony mass, that cling to stems and leaves - will remind you to do so. Mealybugs are an indication that growth in a plant is too dense, that insufficient light is reaching the interior of a plant, or that the air circulation around and through a plant is inadequate. Many species of acacia, if they are in any way deprived of the good light that is their due, will also become infested with mealybugs.

Bring in the pros

If you have a mature tree that has lost large branches in the recent windstorm, this is a sure sign that it needs pruning. Just make sure that you have a certified arborist do the work. Trimmers who do not know how to prune trees usually chop them back brutally and charge little for the carnage they inflict. Within a year or two, many weak branches - the kind that come down in windstorms - will have grown back on such improperly pruned trees.