Question of the Week © 2017 Mike McGrath
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Shred Your Leaves & Fall Into Composting!
Q. I composted last year's shredded leaves with coffee grounds, turned the piles, and finally have finished compost! Should I put it on my beds now—in the Fall? I need to make room in my compost bins!
---Andy in Pitman, NJ
A. Andy has discovered the hard reality and awkward timing of composting in climes with cold winters. Although you always get some finished compost by planting time of the following year (hiding on the bottom of the shredded leaves), a lot of the material won't be done until the weather heats up in late Spring and Summer—even with shredding, turning, and adding Nitrogen-rich coffee grounds.
I was personally disappointed by the un-finishedness of my compost this Spring. It was such a cold winter that the 'King of Compost' got a big crack in his crown.
On the other hand, once we got to June and July, I was turning new piles of kitchen waste and last year's shredded leaves into finished compost in a month. And, like Andy, I wound up with a lot of finished material that I had to use this fall to make room in my bins for this year's fine crop of fall leaves.
It all comes down to time and temperature. Down in the Carolinas, a much higher percentage of fall-prepared compost is going to be finished by Spring, and cold climes will need more time. But compost always eventually happens, and anytime is the right time to spread finished compost!
I've been spending a lot of my Autumn spreading most of my finished compost on top of my raised beds and around my peach trees. I'll protect that precious resource from leaching its nutrients over winter with an inch of well-shredded leaves on top, applied after the soil freezes hard for the season. (Remember: winter mulch should go on after the soil freezes, not before.)
Now you may note that I just said 'most'; what about the rest of my finished compost?
I'm saving some of it in a lidded trash can and a covered wheelbarrow so I have it handy to perk up any piles that don't seem to be moving along fast enough over the winter. And I am mixing large amounts into every fresh batch of this year's shredded leaves. I've gotten a little lazy about taking advantage of the old trick of mixing finished compost into new piles, but the life in that finished compost is a great way to kick-start a new pile, and I hope that my having a heavy hand with that 'old compost' now will lead to a better (faster!) harvest in the Spring.
Q. Mike and his guests were encouraging the shredding and mulching of leaves on a recent show, and Mike recommended a heavy grade machine to do it. What exact unit is recommended?
---Jill in Chester Springs, PA
A. She's referring to the recent anniversary show we did with Lee Reich and Howard Garrett; composting was a hot topic that day! And I love to talk about shredding leaves; you get compost years faster when you take the time to shred the leaves…
A bagging lawnmower works well to shred and collect leaves. If the lawn they're on has not been treated with chemical herbicides, the small amount of grass clippings that also get picked up will help the leaves compost faster. But if the lawn has been treated with chemical herbicides, just mow the leaves back into the lawn—don't make compost with those contaminated clippings. (And switch to corn gluten meal and other natural herbicides from now on!)
My personal shredding tool of choice, however, has always been an electric blower/vac; a dual purpose machine with one really dumb use and one that's essential….
The 'dumb' use, of course, involves the blower part. You make a whole bunch of noise, blow a lot of junk up into the air and the leaves are still on the ground when you're done. Makes about as much sense as bringing pork chops to a Seder.
The good use is when you switch out a few parts, attach the collection bag and use it as a leaf vac; that way the leaves actually get picked up—and these machines automatically shred them into much smaller pieces. As we've said many times, a gardener can save at least 10 or 12 bags worth of whole leaves in a single bag once they're shredded.
There must be a dozen different electric blower vacs on the market, and the models are constantly changing, but the first thing you want to look for is a machine that definitely performs both functions—some are just blowers. It should say it right on the box—and often there's a picture of the collection bag that holds the shredded leaves.
Now: when I first emailed our listener with a briefer answer, I told her to look for a machine that has a high 'mulching ratio'—that a ratio of '10 to 1' would be good; and '20 to 1' would be twice as good…
But then the high-end catalog company Hammacher-Schlemmer sent me a really neat cordless rechargeable model to test this Fall that only claims a 10 to 1 ratio—you know, turning ten bags of whole leaves into one bag shredded; but it's much better than that. It's producing some of the smallest particle sizes I've ever seen; significantly smaller than my old Toro corded model, which claims 16 to 1. So the listed 'mulching ratio' numbers may not be a good indicator.
How to choose? Maybe read some online reviews, and then make sure your final choice performs both functions, has a metal impeller and a decent warranty.
You'll typically pay around a hundred dollars for a really high-quality corded blower vac. The rechargeable one I'm testing retails for three hundred—so it's not for everybody. And you're limited to shredding two to three bags at a pop before you have to stop and recharge the battery. But you get a fresh charge in a little over an hour and a half—and I am loving being able to get leaves in places I just can't reach with a cord.
Bottom line: However you do it, shred all the leaves you possibly can this fall. Because you always need more than you think, and you won't get another chance until next year!