When Compost Stinks...

This Compost Doesn't Smell Because It Has the Right Mix of Ingredients

If your compost stinks or smells kind of barfy then it is out of balance. It is easy to make compost that doesn't smell bad when you understand the four things required for proper decomposition. Compost needs a balance of:

• high nitrogen ("green") materials
• high carbon ("brown") materials
• water
• air

"Green" stuff includes fresh grass clippings, kitchen scraps, coffee grounds, manure, fresh weeds, and fresh leaves. (Note that they aren't all necessarily green in color.)

"Brown" stuff includes dried leaves, dried straw, and dried weeds, tiny wood chips or sawdust. (Note that they aren't all necessarily brown in color.) 

When the balance is right, compost will heat up. Properly made compost has very little smell, and when it is completely broken down it actually smells wonderfully earthy and rich, like fresh garden soil.

This article is the troubleshooting companion article to How to Make Compost, which gives the complete instructions.

If your compost stinks or smells barfy, you either have too much green stuff or not enough air (or both). Too much green (nitrogen) stuff will skew the fungi/bacteria balance in favor of bacteria, which is what causes the smell. And if it needs air as well, it will favor anaerobic bacteria (which really smell bad - like barf!)

To cure a case of "compost stinks", turn the pile with a garden fork and add plenty of dry leaves or straw to any wet or airless places as you're turning it, and within a couple of day the smell will stop.

If you're using one of those black plastic compost bins, lift the whole bin up and off the pile and set it down next to the pile of stuff that was in it. Then, one forkful at a time, move the compost over into the bin in its new location, adding the "brown stuff" into the mix as you do so.

If the pile is very slow to break down, you either have too much brown stuff or not enough water. Moisten the pile and mix in some fresh grass clippings or big bags of used coffee grounds from your local coffee house.

Even though coffee grounds are brown in color they are considered "green" because they're high in nitrogen. You can get them for free at most coffee hangouts, including Starbucks nationwide. I use them a lot, because they're a great nitrogen source (and they always smell good!)