GARDENING\For backyard farmers, it's mulch ado about orchards.

Byline: Joshua Siskin

A backyard orchard. What could be nicer? An orchard is the dream of every hemmed-in, hedged-in homeowner with a diminutive, sun-starved back yard.

But an orchard may not be the storybook affair that the mind would conjure up. The plums are always peachier on the other side of the fence. Or perhaps the peaches over there are just more plum.

Augusta Chadwick of Chatsworth writes as follows: "We have a mature home orchard ... approximately 20 fruit and nut trees and grapevines with every problem in the book plus others. Is it beneficial to dig fallen leaves into the trees' basins to promote mycorrhization? Should fine shredded pepper tree limbs be used in the basins of fruit trees?"

First of all, Augusta, I'm somewhat concerned about the "basins" to which you refer. There should not be any basins around trees. At planting time, a circular hill of earth (berm) should be built several inches out from the trunk to allow water to soak in, but a basin which is lower than the soil level should never be created. If your tree trunks sit in the bottom of basins or dishes that are below the surrounding grade, you will not get optimum production from your trees. Furthermore, such trees risk asphyxiation from water standing around the crown (area where trunk meets soil), which must be kept dry.

I am also worried about your interest in digging leaves into the soil under a tree. Such digging could kill feeder roots close to the soil surface and would not be beneficial. Just lay the leaves on top of the soil beneath the tree canopy and, within about four months, they should be substantially decomposed. The minerals taken up by the trees during the past growing season will have found their way back into the soil from whence they came, to be absorbed by tree roots once again.

As you suggest, mycorrhizae, the soil-dwelling fungi that make certain minerals available to plant roots, benefit enormously from a leafy mulch.

Your use of shredded pepper tree limbs as a mulch should be no more troubling than the use of any other shredded wood, be it pine, cedar, oak, sycamore or eucalyptus. I realize there is some controversy about the use of certain mulches around fruit trees. It has been suggested that the tannins and oils in certain leaves, woods and barks are detrimental when used as mulches in orchards. I have not found this to be the case, but it is always wise to put a thin layer of aged manure or finished compost on the ground before mulching an area for the first time. The compost will supply the bacteria and humic acid needed for the decomposition and neutralization of the mulch.

Chadwick also wants to know "what causes small-leaved ice plant to die. Big sections of it on our hillside die out." Like ivy and Bermuda grass, ice plant roots as it grows. Wherever an ice plant node (the point where leaf meets stem) touches the ground, roots are formed. This makes it an excellent plant for erosion control on slopes, but also a prime candidate for thatch buildup. Thatch is a layer of stem tissue - most of it dead - which accumulates between actively growing leaves and the soil surface. Thatch may become so thick that water and fertilizer can no longer find their way down to the roots, causing the plant to die.

There are two other factors that may have led to the death of this ice plant. The first is not enough sun; small-leaved ice plant - the kind that produces either purple or pink flowers - requires full sun exposure to thrive. Another problem could be excessive water, which could bring on soil fungus. Remember that ice plants are from South Africa, the climate of which is the mirror image of our own. This means that watering of ice plant should be minimal during the summer to prevent activation of water molds. Soak established plantings no more than once a month.

Clara from Chatsworth wants to know the right time of the year to prune geraniums. Geraniums can be pinched or cut back any time except now, because they are frost sensitive. Just before spring, severely cut back ivy geraniums - because of their rampant growth - in order to maximize flower production during the warm season.

Clara also asks about the pruning of climbing roses. The recommended practice is to cut back all the vertically growing stems, but to leave the horizontal branches intact. Absent vertical branches, the hormonal balance in plants shifts sharply in the direction of flower production. This same philosophy is behind cordon pruning of grapes and horizontal espaliering of apple, pear and plum trees. In all cases, the plants' flowering - and hence fruiting capacity - is increased.

Tip: Now is the time to hard prune your roses. With hybrid teas, canes should be 18 inches to 3 feet tall after pruning. Light pruning will produce more roses; heavy pruning will produce fewer but larger blooms. The increasingly popular shrub and floribunda roses can either be selectively thinned out or sheared - like any other flowering woody perennial.