How does one determine the ratio of browns to greens in compost?


How does one determine the ratio of browns to greens in compost? A bag of leaves is light and air-filled, whereas a green scrap container is dense. Does one compact the leaves to create the same density? And how so? Stomping on the bag? Smashing with a hammer?


Thanks for contacting the Toronto Master Gardeners. It’s great to know that you are composting ! Composting is so good for the garden and for the environment. The key to success is to find what works best for you so that you can keep doing it without a lot of effort for great results in your garden. It doesn’t have to be complicated.

The ideal ratio of brown and green material for composting is 3 parts brown/carbon rich material to 1 part green/nitrogen rich material, measured by volume. This ratio promotes the creation of quicker (ideal microbe growth and working efficiency) and better (30:1 carbon : nitrogen, ideal for use in the garden) compost.

Compostable materials can be chopped and shredded before being added to the compost pile, but they don’t need to be. Larger pieces will just take longer to break down. Fallen leaves can be shredded by going over them with a lawn mower while they are on the lawn, or by putting the leaves in a garbage can and using a string trimmer on them (eye and ear protection required). There are also leaf blowers that have leaf shredding capability. Or you can use a bucket to gauge the amount of green vs brown material that you are adding to the compost pile (3 buckets of brown for every bucket of green), and for fallen leaves, put them in the bucket and squish them down to remove air. Note that oak leaves break down more slowly than other types of leaves, so shredding them can speed up their breakdown process.

Here are a couple of websites with information about composting that you might find helpful :

Compost how to guide based on science

How to Compost : Browns & Greens

Happy composting !

Nov 22, 2021