Turning Over an Old Leaf

Some people rake each leaf as it falls, others wait for the entire drop before gathering themselves for action.

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Either way, leaf raking (or blowing) are necessary autumn chores. Some people love it, viewing it as mental therapy that soothes the stress of the workaday world, others find it a tedious drudge.

Gardeners cringe, though, when they see the fruits of all that work piled on the curb or in bags for the municipality to collect. Leaves are one of the most valuable raw materials for building the soil, which is the foundation for every successful garden.

If leaves are so good for the soil, you might ask, why do we bother raking them up?

Apart from the obvious need for neighborly tidiness, the task is good for the garden. Clearly, leaves that mat and smother the lawn will kill areas of grass by robbing the turf of sunlight. But piles of leaves also pose risks in plant beds by stealing light, promoting fungal diseases and harboring pests.

In addition, leaves can stack up at the base of shallow-rooted plants such as azaleas and boxwoods and promote root growth above the soil surface: When the leaves rot or wash away, the plant is left with roots growing in the air, permanently stressing the shrub.

Raking presents its own challenges. Some plants won't yield their cache of fallen leaves without a fight, and heavy-handed raking may damage them. Cotoneasters, Japanese maples, winter jasmine and spreading junipers fall into this category. You may have to hand-pick the leaves, wearing gloves.

If you have just laid mulch and the leaves sit on top, raking may disrupt all that carefully laid material. A light sweep of the rake will do the job, as will a deftly operated leaf blower. Next year, lay the mulch after the leaves have dropped.

Textbooks will tell you to use the gathered leaves on a compost pile, a worthy undertaking but one with its own demands and pitfalls.

If you don't want to go to that trouble, you should gather the leaves in an open area and use a lawn mower to shred them. This will speed their decomposition. You can then either use the shredded leaves as a light mulch, or spread them on your beds and work them into the soil. The latter course will more quickly draw earthworms, nature's composters.

The garden composter has two basic choices: create an active pile in which microbes heat up the matter and break it down quickly, or the more passive approach of allowing the vegetation to rot at its own pace. The second type of pile will take months to break down and may turn foul through lack of oxygen.

For the active method, mix the leaves, which are high in carbon, with a nitrogen source such as grass clippings, horse manure or vegetable waste, and pile the concoction into the compost bin. Use snow fencing or chicken wire, with corner supports to contain the pile.

It must be large enough for microbes to reach a critical mass but not so large that the material cannot be turned. One cubic yard is a typical recommendation.

Allow the bin to open at the front to turn the pile, which should be done occasionally with a pitchfork. This gets air to the whole pile. Also, it should be kept moist but not wet: You will have to water it in dry spells, but cover it with plastic during periods of heavy and prolonged rains.

The pile should be broken down sufficiently to use as a soil amendment next spring.

Purists will sift the material through a screen--called a riddle in gardening parlance--to remove twigs and other uncomposted bits.

For more information on home composting, visit the Web site of the Virginia Cooperative Extension Service at www.ext.vt.edu. Go to "information resources," "landscape and nursery," "yard waste management" and "making compost from yard waste."