Start with the two categories: greens and browns

A working compost bin needs both greens (nitrogen-rich materials) and browns (carbon-rich materials) in roughly equal amounts by volume. Greens heat up the pile and break down fast. Browns slow that process and create air pockets so the pile doesn't turn into a wet mat. Without both, you either get a smelly, anaerobic mess or a pile that barely changes for months.

The ratio that works for most home bins is about one part greens to two parts browns, though you will adjust this by feel as you go. If your pile smells like ammonia or rotting eggs, you have too many greens. If it is not heating up and nothing is breaking down after a month, you need more greens.

Greens: what to add regularly

Greens are fresh plant material and food scraps. Add grass clippings (from lawns not treated with herbicide), vegetable and fruit scraps (peels, cores, wilted lettuce, carrot tops), coffee grounds and tea bags (remove the staple from tea bags first), plant trimmings (deadheaded flowers, pruned stems), and fresh manure from herbivores like horses, chickens, or rabbits if you have access to it.

Do not add meat, fish, dairy, oils, or cooked food — these attract rats and create odor problems that take months to resolve. Avoid diseased plants and weeds with seeds; both can survive the composting process and spread problems in your garden later. Pet waste and cat litter do not belong in a bin you will use on vegetables, even if they technically decompose.

Browns: the backbone of your pile

Dry leaves are the easiest brown to find in fall and the most forgiving to use. Shredded paper and cardboard (no glossy coatings or colored inks) work well and are free if you shred your own mail and boxes. Straw and hay (not hay with seeds still in it) add bulk and air space. Wood chips and sawdust from untreated wood break down slowly but last a long time in the pile.

Newspaper, plain cardboard, and paper bags all count as browns. Tear or shred them into pieces smaller than your hand so they do not mat down. Pine needles and conifer bark are acidic and break down very slowly, so use them sparingly if at all. Avoid treated wood, glossy paper, and anything with ink that is not soy-based.

Materials that seem like they should work but don't

Citrus peels and onion skins take much longer to break down than other food scraps and can repel worms if you are using a worm bin. Add them in small amounts mixed with other materials. Avocado pits and shells are so dense they may still be recognizable a year later; chop them into smaller pieces or skip them.

Bread, pasta, and grains attract rodents just like meat does, so leave them out. Glossy or colored paper contains inks and coatings that do not break down and can leach into soil. Sawdust from treated wood (pressure-treated, painted, or stained) introduces chemicals that persist through composting and contaminate your finished product.

Layering and moisture balance

Alternate layers of greens and browns as you add material — a few inches of greens, then a few inches of browns, then repeat. This mixing happens naturally as the pile settles and as you turn it, but starting with layers helps prevent the greens from clumping together at the bottom.

The pile should feel like a wrung-out sponge: moist but not dripping. If rain has soaked it, add more browns to absorb moisture. If it is dry and nothing is breaking down, add water or more greens. A bin that is too wet smells bad and slows decomposition. A bin that is too dry straightforward sits there.

Turning and timing

A pile that you turn every week or two will produce finished compost in six to eight weeks. A pile you leave alone will take four to six months or longer. Turning mixes the materials, introduces oxygen, and speeds decomposition. You do not have to turn it — passive composting works fine — but turning is the fastest way to get usable material.

You will know compost is ready when it looks like dark, crumbly soil, smells earthy, and you cannot identify the original materials. At that point, move it to a separate bin or pile and start filling the original bin again.

Key Takeaways

  • Greens (grass, food scraps, plant trimmings) and browns (leaves, cardboard, straw) must both go in your bin in roughly equal amounts by volume for the pile to heat up and break down efficiently.
  • Never add meat, fish, dairy, oils, cooked food, diseased plants, or pet waste, as these create odor, attract rodents, or spread disease to your garden.
  • Keep the pile as moist as a wrung-out sponge and turn it every week or two if you want finished compost in two months instead of six.
  • Citrus peels, avocado pits, bread, and glossy paper break down slowly or not at all and should be left out or used very sparingly.
  • Finished compost looks like dark soil, smells earthy, and shows no recognizable original materials — at that point it is ready to dig into garden beds or potted plants.

Frequently Asked Questions

Can I put diseased plant material in my compost bin?

No. Most home compost piles do not heat up hot enough or long enough to kill fungal spores and bacteria that cause plant disease. If you add infected leaves or stems, you risk spreading the disease back to your garden when you use the finished compost. Throw diseased material in the trash instead.

What if I don't have leaves in winter?

Shredded paper, cardboard, straw, and wood chips all work as browns year-round. You can also save leaves in fall in a separate bin or bag and pull from that supply during winter. If you have access to grass clippings or fresh manure, those greens will heat the pile even without fresh leaves.

Do I need to chop everything into small pieces?

Smaller pieces break down faster, but it is not required. Whole leaves and large cardboard pieces will eventually decompose. Chopping or shredding speeds the process from months to weeks and makes it easier to layer materials evenly. A leaf shredder or running a lawn mower over a pile of leaves works well.

Can I add weeds to my compost?

Only if the weeds have not gone to seed. Weed seeds can survive the composting process and sprout in your garden later. Pull weeds before they flower and set seed, then add them to the bin. If you are not sure, throw them in the trash to be safe.

Why does my compost smell like rotten eggs or ammonia?

That smell means the pile is too wet and has too many greens, creating anaerobic (oxygen-free) conditions. Add more browns, turn the pile to introduce air, and let it dry out a bit. The smell will fade within a few days once oxygen gets back into the material.