There are a lot of dos and don’ts when it comes to composting, and if you’re running an urban compost pile, the list of rules to follow gets even lengthier. The basic premise is simple enough, though — keep a good balance of “green” and “brown” material, and turn the pile frequently. City dwellers are advised to keep various materials out of their compost piles so as not to attract rodents, but many of those materials are in fact great for making compost. I’m not trying to brag here, but my urban compost pile smells like it came straight from the farm, so I figure I must be doing something right. I thought I’d take a few moments to share a little about my haphazard route to success.

First a few words about those few words, “green” and “brown”. What we’re getting at is the ratios of carbon and nitrogen you want in your pile. Materials that are high in nitrogen are considered “green” materials, and materials that are high in carbon are considered “brown”. Not all greens are green, though. Coffee grounds are a great source of nitrogen in your pile, and while their color is brown they are considered a “green” material as far as your compost. Human or pet hair is also high in nitrogen, and is considered a “green” source no matter the color of your or Fido’s locks.

The biggest problem with most urban piles is not enough brown material. Some overlooked sources include shredded fall leaves, if you can get them, or shredded newspaper, office paper, or cardboard. No glossies, though. Most paper plates are coated in some sort of petroleum product, but plates marketed as compostable are becoming more available. They are heavier than typical paper plates and sort of resemble cardboard. Make sure to shred all of these materials well or turning your pile will become a chore. The smaller you can shred up these materials, the quicker your pile will break down. The ideal size for all materials, green and brown, is nothing larger than half an inch. Although I do trim all material with a hand pruners before it goes into my pile, I’m not that fastidious, and find that pieces up to a few inches or so in length compost adequately.

Now, what about the materials you aren’t supposed to compost? Meat and dairy products especially are notorious for attracting rodents to compost piles. Maybe it’s the prevalence of coyotes in my urban neighborhood, but I have been composting limited amounts of meat and dairy products in my compost pile with no sign of unwanted critters. I use two of those black plastic “Darth Vader helmets” for a two bin system in my backyard composting operation. I’m not a big fan of these units for ergonomic reasons, but they are fairly critter proof and present a tidy appearance if that is a concern. I have on occasion seen rats in my neighborhood and even inside my building (eek!), but never in or near my compost pile. After twenty years of urban gardening, I’m well familiarized with rats and their behaviors, and I speak with confidence when I say that they just haven’t been a problem with my current setup. Keeping those lids tight is your best line of defense against unwanted visitors.

I’ve heard that you can compost an entire cow, bones and all, in a well tended compost pile in just seven days. I would not advise trying this in one of those Darth Vader helmets, but I have thrown in a few steak and chicken bones as well as plenty of spoiled milk or yogurt. These are prime ingredients for getting real biology into your compost pile. Recently I made a few gallons of stock, roasting beef and chicken bones and boiling them overnight with plenty of herbs and root vegetables. That success should be another blog post entirely, but after straining out that spent material, I added the veggies and sludge to my compost pile (the beef bones went to the neighbor’s dog). This is exactly the sort of thing you are advised not to do with an urban pile, and I think it’s one of the prime reasons my urban compost smells like the best fresh manure.

The smell test is always your best test when it comes to judging your compost. The nose knows, as they say. Forty-thousand years of human biology are working to your advantage here. A good compost pile should smell like a forest floor, a rich earthy smell, not at all sour. If your pile reeks of ammonia when you turn it, you have too much green material. Add more brown and turn it in well. If it smells like sewer muck, your pile has gone anaerobic. Probably it has gotten too wet or has not been turned enough, and all of the oxygen has been used up. Giving the pile a good turn and adding plenty of fresh material will give the pile a kick start and you can still get usable compost.

There could be some concerns about bacteria or other pathogens when adding meat or dairy products into your compost system. My pile runs hot! hot! hot! and anything in there is definitely getting cooked. Again, watch your ratios and turn the pile frequently. I’ll throw weeds that have gone to seed in the pile without worry. You can also keep in mind the intended use for your finished compost. I’m not using my compost for veggie production, it’s mostly feeding perennials or filling in bare spots of lawn. I’ve thrown in expired pharmaceuticals and some other materials I might be leery of adding to my veggie plots, but it’s of no concern where I’m growing prairie plants. Since I have a house rabbit, I have plenty of manure to add to my veggie production beds, and I use the compost bins to generate soil for the rest of the yard (where it’s badly lacking).

Maybe I’m relying on experience, but I don’t think too much about my composting. I just make a habit of checking the pile at least weekly, burying any new material well in the compost pile and giving it a good turn when I can. I’ll adjust the ratios as I go. My “two bin system” is as follows – one bin is the active compost bin, and the other is pretty much for storing brown material until I need to add it to the hot pile. The brown bin might get some green material mixed into it, again I’m not fastidious, but the ratio is overwhelmingly toward brown and it won’t compost on its own.