How to Turn Fall Leaves Into a Great Summer Garden
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Q. Mike: Last summer I built a bin and filled it in the fall with shredded leaves. The bin had a cover (as designed). But in the Spring the volume of shredded leaves was only slightly reduced, and just the smallest bit of compost was in the very bottom. We really want the results to be better next year. We've already decided to remove the cover. What else should we do to get that rich-looking completely degraded compost you see in gardening books by next spring?
- ---Gene in Wyncote, PA
- ---Robert in Tallahassee FL
Now, down in Tallahassee and other warm winter climes, leaves collected and shredded late in the season should be almost completely composted by the Spring—unless the pile gets dry, which slows the process down considerably. Where rain is scarce (or when you compost in a sealed bin), you should water your raw ingredients occasionally. If the top of an open pile is shedding water, just break it up a little with a pitchfork now and then.
Or, if you want to keep it moist and move the process along faster, 'turn' the pile by forking the material over to another spot to mix the damp leaves with the dry. If you don't want to—or can't—engage in that type of labor, there's a really handy tool known as a compost aerator you can plunge in and then pull out of the pile. It slides in straight like an arrow, but little 'wings' pop out on the upstroke, really mixing things up and making it easier for rainwater to get through.
In the North however, the reality of winter sets in. It gets cold right after we collect and shred those leaves, and as many of us know all too well personally, biological processes slow down in the cold. (If trees were more considerate, they'd drop their leaves in the Spring!)
And covering an otherwise open compost pile is a bad idea in all but the rainiest climates. You make compost the fastest when the material stays damp, and winter rains and snow often add just the right amount of moisture to the mix. (With a sealed composter, you can just take the lid off occasionally when wet weather is predicted. If it's a tumbler, rotate the drum so that the openings face up and then take the doors off during a rain event.)
But there's still that darn cold to contend with in most of the nation, so here are some ways to help things cook a little faster:
- Always shred your leaves before using them as mulch or to make compost. Whole leaves mat down like a tarp, keeping air and water out of compost piles and any soil they may be foolishly covering. (In the wild, trees use their leaves to suppress competition on the forest floor by smothering littler plants.) So shredded your leaves must be. The best tools to accomplish this task are chipper/shredders, leaf blowers that have a reverse 'vacuum' setting, dedicated leaf shredders that fit on top of trash cans and bagging lawn mowers.
- Try double shredding your leaves. The smaller the particle, the faster it becomes compost. My leaves were also a little slow to degrade last winter, so I plan to run them through my leaf vac twice this fall. A little extra work from which I expect big rewards.
- Give them some nitrogen. Mixing a rich source of nitrogen in with your fall leaves will move the process along much faster and keep it going longer into cold weather. I've been hoarding and collecting used coffee grounds all summer for this task; they're super-rich in nitrogen, add moisture to the pile, don't attract vermin and are readily available. (Ask your local coffee shop for their used grounds and/or take the used grounds home from the coffee station at work.) If you have an untreated lawn, running a bagging mower over it to shred your leaves up with some grass clippings makes for a perfect compost mixture; like coffee grounds, grass clippings are a great source of moisture and nitrogen. But don't use clippings from a lawn that's been treated with chemical herbicides; the resulting compost could kill next year's plants. (If you don't believe me, just search the word "Imprelis".)
- Put a chimney in the middle. Roll some animal fencing into a tube that will be taller than your stack of raw ingredients, place it in the center of the area you're going to use and then pile your contents around it. That 'compost chimney' will allow air and water to reach the parts of the pile that are always the most recalcitrant.