WHAT'S GOOD FOR THE SOIL IS GOOD FOR THE PLANT.

Byline: >JOSH SISKIN

What food do you recommend for tropical and other plants flowering now, such as jasmine, stephanotis, plumeria, jacaranda and lavender?

>P.M. Okada, Glendale

A fertilization philosophy is more important than the actual fertilizers you apply. Fertilization is not so much a solution to a plant's nutritional needs as it is a strategy of ensuring long-term health, not only for plants but for the soil they inhabit.

It should be noted that "plant food" is not something that can be externally supplied since plants make their own food, which is sugar, from carbon dioxide and water. What we can provide are the mineral elements that make leaves green, enhancing their light-trapping capacity while also serving as catalysts for photosynthesis and other physiological processes.

The mineral elements needed by plants can be provided immediately with fast-acting fertilizers or, a little at a time, with mulch. If you mulch properly, the humus that is eventually created in the soil will provide constant mineral sustenance for your plants. The best testimony to the benefits of mulch can be found in the classic book, "Gardening Without Work," by Ruth Stout.

"My no-work gardening method is simply to keep a thick mulch of any vegetable matter that rots on both my vegetable and flower garden all year round. As it decays and enriches the soil, I add more. The labor-saving part of my system is that I never plow, spade, sow a cover crop, harrow, hoe, cultivate, weed, water or spray.

"I use just one fertilizer (cottonseed or soybean meal), and I don't go through that tortuous business of building a compost pile. I beg everyone to start with a mulch 8 inches deep; otherwise, weeds may come through, and it would be a pity to be discouraged at the very start," Stout writes.

Mulching materials suggested by Stout, who gardened into her 90s, include "hay, straw, leaves, pine needles, sawdust, weeds, garbage -- any vegetable matter that rots."

Although Stout utilized her method in vegetable and flower gardens, there is no reason it could not be applied to ornamental and perennial gardens as well. In the typical Valley garden or landscape, however, we would have to get over our obsession with covering every square inch of ground with plants, especially those wall-to-wall ground covers that make mulching impossible.

It has been said that instead of focusing on feeding our plants, we should think in terms of feeding the soil. Plant health depends, in no small part, on the health of the beneficial bacteria, fungi and mycorrhizae that reside in the top few inches of soil. For these oxygen-dependent organisms to flourish, the soil must be friable, porous and soft, allowing maximum gas exchange. The most effective soil-softening agent is mulch.

If you are not ready, for whatever reason, to mulch your garden and want to fertilize now, I would recommend Gro-Power or GroMore products since they contain beneficial aerobic bacteria.

Plumeria, with those fragrant pastel pinwheel flowers used in Hawaiian leis, requires a high phosphate fertilizer such as Peters Super Blossom Booster (10-50-10) or Schultz Expert Gardener Bloom Plus (10-60-10).

In the three number fertilizer analysis, the middle number (50 or 60) represents the percentage of phosphate (makes more flowers and strong roots) in the fertilizer. The first number is the percentage of nitrogen (makes leaves green), and the last number is the percentage of potassium (makes strong stems and provides overall resistance to stress).

Stephanotis, a vining plant with fragrant white blossoms, should be fertilized monthly with a soluble fertilizer, such as Miracle-Gro, applied at half the recommended strength. Lavender, a Mediterranean plant, goes quasi-dormant in the summer, and should not be fertilized at this time.

Tip of the week: If you see ropy grass crawling along here and there in your lawn, know that you have the beginnings of a kikuyu infestation. This grass must be sprayed with a systemic herbicide in order to be killed. However, if you let kikuyu take over your yard, you will find it impervious to drought and dogs.