What’s with all the “browns” and “greens” chatter in composting? Inputs to compost are all the colors of the rainbow, not just brown and green. So why the terms and, more importantly, how much of each do you need in your compost bin?
Read on for all the details about how much “greens” and “browns” you need in a compost pile. Hint: It’s not as scientific as you think.
If you’ve done research on composting at home, you’ve almost certainly heard the terms “greens” and “browns”. If not, that’s totally ok too. We’re going to start from the beginning.
Generically, the terms “greens” and “browns” represent the nitrogen and carbon inputs to your compost pile, respectively. Check out this past post that digs into what constitutes “greens” and browns” in more detail as well as the four components of a healthy compost heap.
Many resources on composting suggest a particular volume ratio of “browns” (or carbon materials) to “greens” (or nitrogen materials). The “right ratio” to perfect your compost pile is all over the map. What’s that all about?
W think you should throw all those simplified ratios in the trash (or the compost bin, as the case might be). If you’re composting at home to simply reduce landfill waste and replenish the soil, here’s why you should forget the darn ratios.
Forget The Perfect “Browns” and “Greens” Ratios
A perfect compost ratio is driven by the relative amounts of carbon and nitrogen elements in the pile. Scientists have determined that compost decomposes most efficiently with a carbon to nitrogen ratio of 30:1 (30 parts carbon to 1 part nitrogen).
That’s all fine and good, but here’s the catch. Each “ingredient” in our compost pile is composed of a unique amount of carbon and nitrogen. Let walk through an example:
Sawdust and oak leaves are both carbon-rich elements to add to a compost pile. However, sawdust has a much higher composition of carbon than oak leaves. If you hope to achieve a 30:1 carbon to nitrogen ratio, that requires far more oak leaves than sawdust given a set amount of nitrogen materials in the heap. You might need three to four times (or more) oak leaves than sawdust to match a certain level of nitrogen materials in the compost bin.
On the other hand, suppose you have a pile of sawdust and plan to add nitrogen materials like coffee grounds or food scraps to the compost bin. As noted above, you hope to achieve a 30:1 ratio of carbon to nitrogen. Coffee grounds have more nitrogen than citrus peels, for example, so you need far fewer coffee grounds than citrus peels to achieve the desired ratio. A cup of coffee grounds adds much more nitrogen to the compost pile than a cup of citrus peels.
All this is to reiterate… don’t worry about ratios. You probably don’t have enough information about the contents of your compost bin and the carbon and nitrogen compositions of each of the items in your bin or pile to know exactly how much of each “ingredient” to add to your pile. Instead…
Sneak A Peek and Take A Whiff
Let’s cut to the chase. Forget about measurements and ratios. The real way to know if you have the right ratios of browns to greens (or carbon to nitrogen) is simply to sneak a peek and take a whiff. That’s it!
Take a look and smell your compost. First and foremost, the compost shouldn’t stink. If it smells like garbage or smells acidic, you have excess nitrogen or “greens”. This wet and stinky pile might also have more bugs flying around it than you would like.
It usually means you added more food scraps than you currently have carbon materials to match or need some additional oxygen. Simply add some “browns” like dried leaves, cardboard, sawdust, or newspaper. Mix them in and let it sit for a day or so.
If your compost looks wet, this could be a result of too many “greens” (or nitrogen) or simply too much water. Either way, add carbon materials and turn the compost to mix in air and help dry it out. The compost should be moist but not soggy.
When the pile looks dry, you probably have either too many “browns” (or carbon) or not enough water. In either case, add more “greens” and some water. Turn the pile to mix everything together and give it a day or two to decompose.
Finding the perfect ratio of “greens” to “browns” while composting at home is more an exercise in trial and error and observation than mastering some perfect mathematical ratio. Don’t get worked up about perfect ratios.
Sneak a peak and take a whiff of your compost pile. You’ll know in ten seconds if you need more carbon or nitrogen materials to find that perfect blend.
If your compost looks damp, dark brown, and has a sweet, Earthy smell, you’ve nailed it. Then you’ll know that you have just the right ratio for your at-home compost heap.
If you have more questions about composting at home, don’t hesitate to ask! Leave your questions in the comments and we’ll do our best to answer them.
If you’re jazzed about composting but this all just sounds like too much, let us do the heavy lifting for you. We provide composting services and love picking up your food scraps on the regular. Check out more about how it works and how to sign up!