PATIENCE -- BREAKDOWN OF MULCH MAY TAKE AWHILE.

Byline: > JOSH SISKIN

The soil in my yard needs help and I like the idea of mulching, but how should I get the material to decompose in our dry climate? And will mulch alone really soften my very hard soil or should I take a pick ax to it before layering on the mulch?

-- Vivian Wood, Woodland Hills

Mulch, for the uninitiated, is any material such as straw, wood chips, leaves, or compost that is distributed over the soil surface to conserve moisture. Side benefits include soil- softening, fertilization and weed control.

Mulch will eventually decompose into rich soil amendment no matter what you do -- including nothing at all -- but the process is accelerated when mulch is kept moist and aerated.

With straw, which is full of air, aeration is not an issue so all you need to do is keep a hose nearby for moistening. (You can find bales of straw at the Red Barn in Tarzana.) Other materials such as leaves, which may easily become compacted, should be turned over or fluffed up with a spading fork on a regular basis to allow oxygen inside.

The decomposing aerobic bacteria that turn mulch into rich earth require moisture (a damp, not soaking wet, environment) and oxygen to thrive. When decomposing bacteria are supplied with these two basic necessities, they proliferate rapidly. The heat that piles of mulch or compost (a mixture of organic materials) may exude is the result of intense metabolic activity on the part of the bacteria that live there.

A limiting factor in speed of decomposition is too little nitrogen, another metabolite of decomposing bacteria. You can add freshly cut grass, manure, or nitrogen fertilizer itself to break down your mulch more quickly. Yet, if you are patient, your mulch eventually will break down and soften your soil in any case. You will notice this process working when, after several months, you move away the mulch layer or compost pile and see a crumbly brown substance, known as humus, underneath.

You could, as you say, bust up the soil with a pick ax, otherwise known as a mattock. Yet, unless you actually mix amendments or well-aged compost into the earth, breaking the ground into pieces will do nothing to soften it.

It has long been said that the garden is the best place on Earth to learn the value of patience. Patience not only is needed to build a healthy soil, but is also required when waiting for perennial plants to establish themselves. It may take several years, or longer for a plant to come into its own but then, when it does, you will be glad you waited.

For years, I had been waiting for a Hebe (HEE'bee) shrub to show its lilac caterpillar flowers and then, finally, this spring, it obliged.

Sometimes a plant will surprise you in unexpected ways. I planted a 'Maraschino' sage a few years ago because of its cherry red flowers and highly aromatic leaves. This water-thrifty shrub has never flowered as much as I would have liked and, at nearly 4 feet tall and wide, has turned into a somewhat unsightly thicket of stems.

I was just about to remove it and try a more garden-worthy specimen when, lo and behold, I discovered a colony of praying mantids hopping from stem to stem at the base of my 'Maraschino' sage. Praying mantids are those long, green, professorial insects that feast on insect pests.

So now I think I'll just prune back my 'Maraschino,' give it a chance to rejuvenate, and let the mantids be fruitful and multiply.

Amazing tree

On the north side of Ventura Boulevard in Studio City, in the corner of a strip mall just east of Radford Avenue, a remarkable tree is growing.

It appears to be Ficus benjamina 'Too Little.' This cultivar, recommended for growing in Bonsai dishes, is supposed to grow no more than 5 feet tall when planted in the ground, although it has reached a height of 7 feet at the strip mall.

The tree is a miniature version, in leaf size and overall stature, of the Ficus benjamina that is used both as an indoor floor plant and as an outdoor, frost-sensitive hedge. The strip mall Ficus exhibits dense, compact growth that would make it an excellent choice for container confinement on a patio, balcony, or pool deck.

Tip of the week

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