Q. Mike: I'm hoping you can help kick-start a new program at our community garden. Historically, we've had one large cold compost heap that was an unmanaged eyesore. The "compost committee" has chosen to move in a new direction and have the individual gardeners create and manage their own composting. Some gardeners are planning to group together and build large 3-bin systems; others just want a small pile for their own 10 x 10 plot. Either way, we're urging them to learn 'hot composting' techniques, as I know that compost that heats up quickly is far superior to the cold kind, and takes much less time to finish. Any advice to get us started on the right track?
- ---Patrick; 'The Spring Gardens' in Philadelphia
Unfortunately, a lot of people start to think about composting in the Spring. They're anxious to get out in the garden, have heard—or know—that compost is a great natural fertilizer, soil amendment and disease preventer, and want to get a pile going. But nine times out of ten—maybe more like 9.9 times out of ten—they don't have THE most important ingredient: Shredded fall leaves.
In the simplest sense, shredded fall leaves are what actually becomes the finished compost. The kitchen waste that gets a lot of recycling-minded people interested in the concept only provides some food for the organisms that turn those shredded leaves into the rich, black "Garden Gold" I'm always proselytizing. Kitchen waste—and other 'wet green' materials—cannot be composted alone outdoors in a pile; it just creates a big stinky mess that's very attractive to vermin. The vast majority of a successful pile must be composed of shredded, 'dry brown' materials like fall leaves.
(Shredded leaves, however, can be composted alone; a wet green nitrogen source is not necessary to create high-quality compost. Some of the best municipal composts—like Maryland's excellent 'LeafGro' product—begin with almost 100% ground-up leaves.)
Unfortunately, gardeners are often obstinate optimists in such matters. They want to start composting NOW, don't have any hoarded leaves and 'Know I'm Wrong'. At least until rats show up wearing party hats and wielding little Wind-in-the-Willows dinnerware.
I've visited Patrick's community garden; it's a nice little urban oasis. But that urban setting makes being realistic about potential vermin problems crucial. Its very easy to breed the nasty, dangerous things, and much harder to get the population to go in the other direction. So here are some ideas.
- Urge every member of the garden to install a worm bin in their home. These indoor systems—some of which are small enough to fit in a tiny apartment—utilize special redworms to turn kitchen waste into 'castings', a natural fertilizer that is just as good, and maybe even a little better than compost. This allows urban and/or leaf-poor gardeners to turn their kitchen waste into a sensational garden input in a safe, sealed vermin-free manner. (The worms can't survive winter outdoors, and the castings have to be harvested and the bedding replaced on a regular basis—so it's dicey to try and establish worm bins in a big, shared garden; much easier for individuals to do indoors. Every home should have a bin!)
- Scavenge every left-over leaf you can find this Spring and shred them up to get a small demonstration pile or two going. Now, Patrick is 100% correct about the superiority of hot compost—that is, a pile that heats up to 140 degrees or so and thus becomes compost quickly. And while most kitchen waste is too low in nitrogen to achieve such heat, nitrogen rich coffee grounds—an abundant free resource in a big, heavily-caffeinated city like Philly—are ideal for fast compost cooking. Mix (don't 'layer') 80% shredded fall leaves with 20% wet coffee grounds, and you'll have finished high-quality compost in a month or less. Without any turning. (Although often promoted, 'layering of ingredients' prevents those ingredients from easily combining, and offers no advantages whatsoever. Mixing dramatically increases composting speed and effectiveness. I have no idea why people recommend layering—it flies in the face of the laws of physics.)
- Get ready for the fall! Figure out how the garden will shred the treasure-to-be and then organize a Merry Band of Leaf Rustlers to stockpile a year's supply of Nature's greatest gift to gardeners. And yes, shredded the leaves MUST be! As lazy/hopeful gardeners soon learn, whole leaves just make a darn good imitation of a tarp. Darn good. Read our previous Questions of the Week on fall leaves (like this one to learn about some of your shredding options.
- Reject bright ideas that try and dance around the leaf requirement. Yes, newsprint and old office paper can technically be composted—that is, changed in form to look like dirt. But because such paper has been heavily processed, the resulting compost will have the nutrition of a Hostess Twinkie—and residues of bleach and dioxin and inks (oh my)! The browned-out remains of last year's big plants, like ornamental grasses and cornstalks, do work as a leaf substitute, but also must be shredded, and can be difficult to work with (especially some of the big grasses, whose 'blades' are well named; so be careful and wear heavy gloves if you go this route).
- Encourage healthy debate on this issue, but keep paper and raw garbage out of communal composts; and keep garbage out of the entire garden, period. Your members can compost the remains of non-diseased garden plants and weeds that haven't gone to seed yet, and they will get some nice compost from these materials without any negative impact—especially if there's a good amount of dirt still attached to the plants' roots. But be warned that things like apple cores and spoiled fruit will quickly turn an urban oasis into a ratty resort.