Starting a compost pile takes about an afternoon and almost no money. The short version: pick a spot or a bin, add roughly three parts “browns” (dry leaves, cardboard, paper) to one part “greens” (food scraps, grass clippings) by volume, keep it about as damp as a wrung-out sponge, and turn it every week or two. In three to six months, the bottom of the pile becomes dark, crumbly compost.
The rest of this guide covers the decisions that trip beginners up: which setup suits your space, why the ratio matters, what the first twelve weeks should look like, and how to rescue a pile that smells or stalls.
Why bother composting?
Food scraps and yard waste together make up more than 30 percent of what US households throw away, according to the US EPA. In a landfill, buried food waste breaks down without oxygen and produces methane. In a compost pile, the same material breaks down aerobically and turns into a soil amendment that improves water retention and feeds soil life. If you garden at all, compost replaces bagged soil conditioner you’d otherwise buy.
What do you need to start composting?
Three things: a place for the pile, a steady supply of browns, and a small lidded caddy in the kitchen for scraps. Tools are optional at first, though a garden fork makes turning far easier. There’s no best system, only the best match for your space and how much effort you want to put in.
| Setup | Cost | Space needed | Effort | Time to compost |
|---|---|---|---|---|
| Open pile | Free | 1 m² / 10 sq ft of yard | Low | 6–12 months |
| Wire or pallet bin | $0–40 | 1 m² / 10 sq ft | Low | 6–12 months |
| Plastic “dalek” bin | $50–100 | 0.5 m² / 5 sq ft | Low | 4–8 months |
| Tumbler | $100–250 | 1 m² / 10 sq ft | Medium | 2–3 months |
| Worm bin (indoors ok) | $30–150 | Under a sink | Medium | 2–4 months |
| Bokashi bucket (indoors) | $40–80 | A corner of the kitchen | Medium | 4–6 weeks to pre-compost |
If you have any outdoor space, start with a simple bin or pile; it’s the most forgiving. You can buy one or build one in an afternoon from pallets, wire mesh or an old trash can, and our DIY compost bin guide compares five builds by cost and capacity. If you’re in an apartment, a worm bin or bokashi bucket works instead, and our guide to composting indoors compares the options.
Where to put it. Choose a level spot on bare soil that you can reach easily in winter, with partial shade so the pile doesn’t bake dry in summer. Close to the kitchen door beats a far corner of the yard; a bin you have to trek to is a bin you stop using.
What is the right ratio of browns to greens?
Compost microbes need carbon (“browns”) for energy and nitrogen (“greens”) to build protein. According to the Cornell Waste Management Institute, the ideal proportion is about 30 parts carbon to 1 part nitrogen by weight. Too little nitrogen and the microbial population never grows large enough, so the pile sits there. Too much and decomposition races ahead, uses up the oxygen, and the pile turns anaerobic and smelly.
You don’t need to calculate anything, but it helps to see why the volume rule works. Cornell’s composting fact sheet lists typical C:N ratios for common ingredients:
| Material | Typical C:N ratio | Counts as |
|---|---|---|
| Food waste | 15:1 | Green |
| Grass clippings | 19:1 | Green |
| Cow manure | 20:1 | Green |
| Horse manure | 25:1 | Green |
| Leaves | 40–80:1 | Brown |
| Bark | 100–130:1 | Brown |
| Paper | 170:1 | Brown |
| Wood and sawdust | 300–700:1 | Brown |
Food scraps sit at half the target ratio and leaves at roughly double it, so mixing them in similar weights lands you close to 30:1. Because dry leaves and cardboard are light and fluffy while scraps are dense and wet, equal weights works out to two to three buckets of browns for every bucket of greens, by volume. Sawdust and wood chips are so carbon-heavy that a little goes a long way; lean on leaves, cardboard and paper as your main browns.
Browns (carbon): dry leaves, shredded cardboard, paper, straw, wood chips, sawdust from untreated wood, paper egg cartons.
Greens (nitrogen): fruit and vegetable scraps, coffee grounds, tea leaves, fresh grass clippings, plant trimmings, crushed eggshells (technically neutral, but they add calcium).
Most beginners’ problem is too many greens, which gives a slimy, smelly pile, because kitchen scraps arrive daily and browns don’t. The fix: stockpile a bag of autumn leaves or shredded cardboard next to the bin, and cover every food-scrap deposit with a double handful of browns.
What should you not put in a compost bin?
Leave out meat, fish, dairy, oily cooked food, cat and dog waste, diseased plants, weeds that have set seed, and treated or painted wood. Most of these either attract rodents or carry problems a backyard pile won’t get hot enough to destroy. Be wary of anything labeled “compostable plastic” too: most need industrial facilities, not a backyard pile, according to the NRDC. Our composting do’s and don’ts has the full table, with the reasons behind each exclusion and the myths (citrus, onions, bread) that cause unnecessary worry.
Build the pile in five steps
- Put the bin bare on soil if you can, since worms and microbes migrate in from below. On concrete, add a few shovelfuls of garden soil to inoculate it.
- Start with a 10–15 cm (4–6 in) layer of coarse browns, such as twigs or wood chips, for airflow at the base.
- Alternate layers: a bucket of greens, covered by two to three of browns.
- Dampen as you go. The University of Georgia Extension puts the target at roughly 40 to 60 percent moisture, which feels like a wrung-out sponge: moist, never dripping. In dry climates, water the pile occasionally; in wet ones, cover it.
- Finish every addition with a layer of browns on top, so no food is exposed.
What happens in the first 12 weeks?
A rough timeline for a bin started in spring or summer and fed and turned regularly. Cold weather stretches every stage.
- Week 1–2: The center of the pile warms noticeably within days if the mix is right. Steam on a cool morning is a good sign.
- Week 3–6: Volume shrinks noticeably as material softens. Food scraps become hard to identify a few inches down. Keep adding and turning.
- Week 6–10: The pile cools between turnings. Woody bits and eggshells remain, but the lower layers start to look like soil.
- Week 10–12 and on: Stop adding fresh material to one batch (start a second bin or pile if you can) and let it finish undisturbed for a month or two.
How often should you turn compost?
Every one to two weeks with a garden fork, if you want compost in months rather than a year. Turning mixes oxygen in, which keeps the aerobic microbes working and the temperature up. A well-fed, turned pile heats to 54–65°C (130–150°F) in the middle, hot enough to speed decomposition and kill most weed seeds. Reaching those temperatures takes volume: aim for at least 1 m³ (about 3 × 3 × 3 ft, or a cubic yard). Smaller piles still work, just cold and slow. If you don’t turn it at all, everything still composts; it just takes a year or so, and the outer layer lags behind the core.
How do you know when compost is ready?
Finished compost is dark brown, crumbly, smells like forest soil, and you can no longer identify what went in, apart from the odd avocado stone or corn cob, which you just toss back in. The pile will also have stopped heating up after a turn. Typical timelines: 2–3 months for a turned tumbler in summer, 4–6 months for a maintained bin, up to a year for a neglected pile.
Use it as a 5 cm (2 in) top-dressing on beds, mixed into planting holes, or sieved into potting mix. If you’re unsure whether it’s finished, let it sit another few weeks; slightly unfinished compost is fine as a surface mulch but can tie up nitrogen if dug into seed beds.
Troubleshooting: smells, pests, and a pile that does nothing
It smells like rot or ammonia. Too many greens or too wet. Turn it and mix in a generous load of shredded cardboard or dry leaves. The smell is usually gone in days.
Rats or raccoons are visiting. Stop adding meat or cooked food if you were, switch to a closed bin with a lid and a base plate, and bury fresh scraps in the center of the pile rather than leaving them on top.
Nothing is happening. Usually too dry or too brown. Water it, add a nitrogen kick (grass clippings or coffee grounds), and turn. A pile that’s too small also stalls.
Ants everywhere. The pile is too dry. Moisten and turn.
Fruit flies in the caddy. Empty it more often, keep a lid on, and sprinkle a little shredded paper over scraps in the bin.
The habit that makes it stick
Composting fails in kitchens, not in bins. Keep a small lidded caddy on the counter for scraps and empty it every day or two; the walk to the bin is the whole system. Pair each caddy trip with a browns top-up, and the ratio takes care of itself. Once the first batch is finished, a second bin lets one pile mature while you fill the other, which is the simplest way to get a steady supply.