Compost turns kitchen scraps and yard waste into free fertilizer, and it needs nothing more than a corner of the yard and a little patience. This guide shows how to start a pile, keep it working, and fix the usual problems.
What compost is and why it matters
Compost is organic material broken down by microbes into a dark, crumbly soil amendment. Mixed into garden beds, it improves drainage in heavy soil, helps sandy soil hold water, and feeds plants slowly over the season.
It also keeps food scraps and leaves out of the trash.
Choose a bin or a pile
You can compost in an open pile, a homemade bin of pallets or wire mesh, or a purchased tumbler. An open pile is free. A closed bin looks tidier and keeps animals out.
Aim for a pile about 3 feet wide, deep and tall. Smaller piles struggle to heat up, and larger ones are hard to turn. Place it on bare soil in a partly shaded spot that you can reach easily from the kitchen.
Browns and greens
Compost needs two kinds of material. Use roughly two to three parts brown to one part green by volume.
| Browns (carbon) | Greens (nitrogen) |
|---|---|
| Dry leaves | Fruit and vegetable scraps |
| Shredded cardboard and paper | Coffee grounds and tea leaves |
| Straw | Fresh grass clippings |
| Small twigs and wood chips | Garden trimmings |
| Sawdust from untreated wood | Crushed eggshells |
What to leave out
- Meat, fish, bones and dairy, which attract pests and smell
- Oils and greasy food
- Pet waste
- Diseased plants
- Weeds that have gone to seed
- Glossy or coated paper
Build the pile in five steps
- Start with a coarse layer. Put twigs or straw at the bottom so air can move through.
- Alternate browns and greens. Add them in layers a few inches thick, finishing with browns on top.
- Add water. The pile should feel like a wrung-out sponge, damp but not dripping.
- Turn it. Mix the pile with a garden fork every week or two to bring in air.
- Keep feeding it. Bury new kitchen scraps in the middle and cover them with browns.
How long it takes
A pile that is turned regularly and kept moist can be ready in two to six months. A pile left alone still becomes compost, but it may take a year.
Finished compost is dark, crumbly and smells like forest soil. You should not be able to recognize the original ingredients.
Fixing common problems
| Problem | Likely cause | Fix |
|---|---|---|
| Bad smell | Too wet or too many greens | Add browns and turn the pile |
| Nothing is breaking down | Too dry or too few greens | Add water and fresh greens, then turn |
| Flies or animals | Exposed food scraps | Bury scraps deeper and cover with browns |
| Pile is slimy | Compacted grass clippings | Mix in dry leaves or shredded cardboard |
Using your compost
Spread an inch or two over garden beds and mix it into the top few inches of soil before planting. You can also use it as mulch around established plants.
If you are building a new bed, compost should make up about a third of the fill. See our guide on building a raised garden bed on a budget for the full soil mix.