How long does it take to make compost?

A well-managed hot compost pile that's turned regularly can be ready in one to three months. A cold pile that's simply left to sit may take six months to two years. Shredding materials and keeping the pile moist speeds things up.

What is the right ratio of greens to browns?

A good starting point is about two to three parts browns to one part greens by volume. If the pile smells like ammonia or is slimy, add more browns. If it isn't heating up, add more greens and water.

Why does my compost smell bad?

A rotten egg smell usually means the pile is too wet and lacks air, while an ammonia smell means too many greens. Turn the pile to add oxygen and mix in dry browns like leaves or shredded cardboard. A healthy pile should smell earthy.

Can I compost in the winter?

Yes. Decomposition slows or pauses in cold weather, but you can keep adding materials all winter. The pile will become active again as temperatures rise in spring, and insulating the bin with straw or leaves can help keep it working longer.

How do I know when compost is finished?

Finished compost is dark, crumbly, and smells like a forest floor, and most of the original materials are no longer recognizable. The pile will have shrunk and cooled to near air temperature. Let it cure for a few extra weeks before using it around young plants.

Composting for Beginners: A Step-by-Step Guide

Every fall I watch neighbors rake up bags of leaves, set them on the curb, and then drive to the garden center the next spring to buy bags of soil amendment. It's one of the great ironies of American gardening. Those leaves, along with grass clippings, spent vegetable plants, and kitchen scraps, are exactly the raw materials for the richest soil builder you can get: homemade compost.

Gardeners call finished compost "black gold" for good reason. It improves drainage in heavy clay, helps sandy soil hold water, feeds the soil life that feeds your plants, and costs you nothing but a little time. I've been composting since my days at Oregon State University, and I still get a small thrill every time I turn a pile and find that dark, crumbly, earthy-smelling material at the bottom.

The good news is that composting isn't complicated. Nature has been doing it forever without any help from us. In this beginner's guide I'll show you how composting works, what to put in and what to leave out, how to choose a bin, how to build and maintain a pile step by step, and how to troubleshoot the problems that trip up most newcomers.

How Composting Works

Composting is controlled decomposition. Bacteria, fungi, and larger creatures like earthworms, sow bugs, and millipedes break down organic matter into a stable, soil-like material called humus. Our job as gardeners is simply to give those organisms what they need to work efficiently.

The Four Ingredients

Every healthy compost pile needs four things:

Carbon ("browns"): Dry, brown materials that provide energy for microbes and give the pile structure.
Nitrogen ("greens"): Fresh, moist materials that provide protein for microbes to grow and multiply.
Air: The most efficient composting microbes need oxygen. Without it, the pile turns slow and smelly.
Water: Microbes need moisture to live, but too much drowns them and pushes out air.

Hot vs. Cold Composting

Hot composting means building a large pile all at once with a good balance of browns and greens, then turning it regularly. The microbes generate heat, often 130°F to 160°F in the center, and can produce finished compost in as little as one to three months. The heat also kills many weed seeds and plant pathogens.

Cold composting means adding materials as you get them and letting the pile sit with little or no turning. It takes longer, typically six months to two years, and won't reliably kill weed seeds, but it requires almost no effort. Many gardeners, including me, do a bit of both.

What to Compost: Greens and Browns

The single most useful thing a beginner can learn is the difference between greens and browns. A good rule of thumb is to aim for roughly two to three parts browns to one part greens by volume. You don't need to be precise; you'll adjust based on how the pile looks and smells.

Greens (Nitrogen)	Browns (Carbon)	Do Not Compost
Fruit and vegetable scraps	Dry fallen leaves	Meat, fish, and bones
Coffee grounds and paper filters	Straw (not hay, which has seeds)	Dairy products and oils
Tea leaves and plain tea bags	Shredded newspaper and plain cardboard	Dog, cat, or human waste
Fresh grass clippings	Wood chips and sawdust (untreated wood)	Diseased or insect-infested plants
Garden trimmings and spent plants	Pine needles (in moderation)	Weeds that have gone to seed
Manure from herbivores (chickens, rabbits, horses, cows)	Dried plant stalks and corn stalks	Clippings treated with herbicides
Eggshells (technically neutral, but fine to add)	Paper towels and napkins (unbleached, no chemicals)	Coal or charcoal ash, glossy or coated paper

Pro tip: Stockpile browns. In fall I fill several bags with dry leaves and keep them next to the bin. All year long, every time I add a bucket of kitchen scraps, I cover it with a few handfuls of leaves. That one habit prevents most smell and fruit fly problems.

A Note on Weeds and Invasive Plants

Annual weeds pulled before they flower are fine in the pile. Weeds carrying seed, and aggressive perennials like bindweed or quackgrass with spreading roots, can survive a cold pile and come back to haunt you. Unless you're confident your pile stays hot, bag those or let them dry out completely in the sun before adding them.

Choosing a Compost Bin or System

You can compost in a simple open pile in the corner of the yard. A bin, however, keeps things tidy, holds heat and moisture, and discourages animals. Here are the most common options.

Open Piles

Free and easy. Best for large yards with plenty of leaves and trimmings. Aim for a pile at least 3 feet wide, deep, and tall so it can heat up.

Wire or Pallet Bins

A cylinder of hardware cloth or four wooden pallets tied at the corners makes an inexpensive, well-ventilated bin. A row of two or three pallet bins lets you have one pile "cooking" while you fill the next.

Enclosed Plastic Bins

These are neat, retain moisture well, and keep pests out, which makes them popular in suburban and urban yards. They're usually smaller, so they may not get as hot.

Tumblers

Tumblers are drums on a frame that you rotate to mix the contents. They make turning easy and keep out rodents. They work best when filled in batches rather than added to constantly.

Worm Bins (Vermicomposting)

Red wiggler worms turn kitchen scraps into rich castings in a compact bin. This is a great option for apartments, small spaces, or winter composting indoors.

Henry's note: At home I use a three-bay wooden bin system for yard waste and a small covered bin near the kitchen door for scraps during rainy Oregon winters. Put your bin where you'll actually use it. A bin in the far corner of the lot tends to get ignored by February.

Hands planting a young plant into a pot of fresh soil

How to Build a Compost Pile, Step by Step

Here's how I build a hot compost pile from scratch. If you prefer cold composting, follow the same layering idea but add materials as they come.

Pick a spot. Choose a level, well-drained site in partial shade, close enough to your garden and kitchen to be convenient. Setting the pile directly on soil lets worms and soil organisms move in.
Lay a base. Start with 4–6 inches of coarse browns like small twigs, corn stalks, or straw. This helps air circulate at the bottom.
Alternate layers. Add a layer of greens 2–3 inches thick, then a layer of browns 4–6 inches thick. Repeat.
Add a little soil or finished compost. A shovelful every few layers introduces microbes and speeds things up.
Moisten as you go. Water each layer lightly so the pile is evenly damp, like a wrung-out sponge.
Build it big enough. Aim for about 3 feet by 3 feet by 3 feet. Smaller piles lose heat; much larger ones can struggle to get air to the center.
Cover the top. Finish with a layer of browns to discourage flies and odors. In very rainy climates, a tarp or lid keeps the pile from getting waterlogged.
Check the temperature. Within a few days the center should feel warm. A long-stemmed compost thermometer takes the guesswork out of it.

Pro tip: Chop or shred materials before they go in. Smaller pieces have more surface area for microbes to work on. Running a lawn mower over a pile of dry leaves is the fastest shredder I know.

Maintaining Your Compost

Turning

Turning mixes the materials and brings in fresh oxygen. For a hot pile, turn it every one to two weeks, or whenever the center temperature starts to drop. Move the outside material to the center and the center to the outside so everything gets a turn in the hot zone. A garden fork is ideal for the job; see our guide to garden forks for the styles that work best on loose, fibrous material.

Moisture

Grab a handful from the middle of the pile and squeeze. A few drops of water should come out. If it's dry and dusty, water it while turning. If water streams out, add dry browns and turn to let it breathe.

Seasonal Care

In winter, decomposition slows or stops in colder USDA zones. That's fine. Keep adding materials and let the pile resume when temperatures rise. Insulating a bin with straw bales or bagged leaves can keep it active longer. In hot, dry summers, a partially shaded spot and a lid help keep the pile from drying out.

Troubleshooting Compost Problems

Almost every composting problem comes down to an imbalance of greens, browns, air, or water. Here's a quick diagnosis chart.

Symptom	Likely Cause	Fix
Rotten egg or sour smell	Too wet, not enough air	Turn the pile and mix in dry browns
Ammonia smell	Too many greens	Add browns like leaves or shredded cardboard
Pile won't heat up	Too small, too dry, or too few greens	Enlarge the pile, add water, or add greens
Dry, nothing happening	Lack of moisture	Water thoroughly while turning
Fruit flies	Exposed food scraps	Bury scraps in the center and cover with browns
Rodents or raccoons	Food scraps attracting animals	Avoid meat and dairy; use an enclosed bin or line with hardware cloth
Matted, slimy grass clippings	Thick layers of fresh grass	Add clippings in thin layers mixed with browns

Safety: Wear gloves when handling compost, and consider a dust mask when turning dry material, since compost naturally contains fungi and bacteria. Wash your hands afterward, especially before eating.

How to Know When It's Ready and How to Use It

Finished compost is dark brown, crumbly, and smells like a forest floor. You shouldn't be able to recognize most of the original materials, though a few twigs or eggshell bits are normal. The pile will also have shrunk significantly and cooled to near air temperature.

Curing

Let finished compost sit for an extra two to four weeks before using it around delicate plants. This "curing" period lets the material stabilize.

Ways to Use It

Amend garden beds: Work 2–3 inches into the top several inches of soil before planting. A good shovel or fork makes quick work of it.
Top-dress: Spread a half-inch to 1-inch layer around established perennials, shrubs, and vegetables.
Lawn care: Rake a thin 1/4-inch layer of screened compost over your lawn in spring or fall.
Potting mixes: Blend screened compost with other ingredients, up to about one-quarter to one-third of the mix.
Mulch: Use coarser, partly finished compost as a mulch around trees and shrubs.

Healthy, compost-rich soil also supports stronger plants that are better able to shrug off pests. Pair it with the strategies in our guide to companion planting for pest control for a garden that largely takes care of itself.

Common Mistakes to Avoid

Too many greens, not enough browns. This is the number one cause of smelly, slimy compost. When in doubt, add more browns.
Letting the pile dry out. A dry pile simply stops working. Keep it as damp as a wrung-out sponge.
Never turning a hot pile. Without oxygen, decomposition slows and odors build.
Adding meat, dairy, and oils. These attract pests and create odors in home systems.
Tossing in big, whole materials. Large branches and unshredded cardboard take ages to break down.
Composting herbicide-treated clippings. Some herbicides persist through composting and can damage vegetables.
Using unfinished compost. Material that's still actively decomposing can temporarily tie up nitrogen in the soil and stunt young plants.

Final Thoughts

Composting is one of the most rewarding habits a gardener can build. It turns yard and kitchen waste into a free, powerful soil amendment, reduces what goes to the landfill, and connects you to the natural cycle that makes gardens grow. Start simple: a pile or bin, a balance of greens and browns, and enough water and air to keep the microbes happy.

Don't worry about getting it perfect. Even a neglected pile eventually becomes compost. With a little attention, though, you'll be spreading your own black gold on your garden beds this time next year, and you may never buy a bag of soil amendment again.

Composting for Beginners: Turn Garden Waste into Black Gold