Fallen leaves can help a garden renew itself

By Barbara Damrosch
Special to The Washington Post
Wednesday, November 10, 2010; 3:36 PM

It's November, and nature is mulching. A year's worth of leaf matter is dropping onto the soil and will protect it in wintertime.

As millions of little food factories detach themselves from twigs and drop, they carry with them a season of sunshine, air, water and minerals, transformed into the makings of compost. They'll join the leaf litter at the bases of trees, where worms, bacteria, fungi and other soil creatures work their alchemy, turning leaf fall into black gold.

Someday, students will wonder at a population that took the fruit of a fertile year, piled it and burned it or stuffed it into plastic bags to be trucked away. To be fair, it is fine for people with small yards to farm out leaf composting to a municipal project, then get back the finished product. But it's worth taking a look at the year's haul and finding ways to put it to use.

A yard is not the same thing as a forest, and there will be areas where fallen leaves are untidy and unproductive, such as the terrace or the drive. But treed spots and shrub beds have a claim to the fertility their own leaves endow. Most ground covers, too, benefit from a weed-smothering leaf mulch - once winter has matted it down a bit - and will come up happily in spring. I let leaves collect in perennial flower beds, too, removing them carefully with a narrow, springy metal rake just before spring bulbs poke up. They can be gathered for the compost pile.

Leaves will do no harm to an emptied vegetable garden. In fact it's a good idea to rake some around tall cold-weather crops such as Brussels sprouts, collards and kale, as they soldier into early winter. Once you've decided where these and other brassica crops will go next year, till or dig some fallen leaves into those beds for an extra dose of nitrogen next summer. They'll love that.

Even leaves that collect on the lawn can be left there if you chop them up with a mower. And no, leaves that collect will not cause thatch.

As for the extras, the best plan is to collect them into a pile (with a lawn rake, not a noisy blower) then contain them within a circle of wire mesh or wooden snow fence. Even a single winter's worth of settling will make them a good mulch for an asparagus bed or a corn patch. Leave them long enough and they will turn into leaf mold - that precious stratum of minutely pulverized leaves that you find under coarser leaf layers in the woods - the last stop before the soil itself. Scoop it out from under your heap and it will make the world's best potting mix in spring, both priceless and free.

localliving@washpost.com Damrosch is a freelance writer and the author of "The Garden Primer."

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