How to Use a Compost Bin Properly

Site it on bare soil if you can, start with a coarse base layer, add browns whenever you add greens, turn it every couple of weeks, and -- the part most guides skip -- stop adding to it when you want to harvest.

• On soil, not paving, where possible. Contact with the ground lets worms and soil organisms move in, which speeds everything up considerably.
• Partial shade. Full sun dries a pile out; deep shade keeps it cold and wet.
• Level and accessible. You will be visiting it in the rain with a bucket, and later with a wheelbarrow.
• Not tight against the house. Any bin will occasionally be opened on a warm day, and you do not want that beside an open window.

1. 1

   Coarse base layer

   Four to six inches of twigs and woody prunings. It lets air in from below and absorbs liquid that would otherwise pool.

2. 2

   Alternate greens and browns

   Roughly one part greens to two or three parts browns by volume. Add a handful of dry material every time you empty the kitchen caddy.

3. 3

   Bury the fresh material

   Open a hole in the middle, tip the scraps in, cover them over. This is what keeps flies away and speeds breakdown.

4. 4

   Check moisture as you go

   Wrung-out sponge is the target. Too wet means browns and turning; too dry means water.

Every two weeks is a good rhythm while a batch is active. With a static bin, fork the outside material into the middle, where the heat and activity are. With a tumbler, a few rotations of the handle does the same job.

Stop turning when the material has stopped heating and looks broken down. The final maturing phase is better left undisturbed.

A bin you keep adding to never has a finished batch in it. There are three ways to get around that, and choosing one is the difference between having compost and having a full bin.

1. Two bins. Fill one, then leave it to finish while you fill the second. The simplest approach, and the reason dual-chamber tumblers exist.
2. Bottom harvesting. Static bins with base doors let you take finished material from the bottom while still adding at the top. Works well if the contents are not too wet.
3. Stop and finish. Stop adding for four to six weeks and let the whole bin mature. You need somewhere to put scraps meanwhile -- the freezer is the usual answer.

Most finished compost contains twigs, eggshell and the odd avocado pit. Push it through a half-inch sieve or a piece of hardware cloth on a frame, and throw the oversized material back into the bin as a starter for the next batch.

Sieving is optional for spreading on a bed and worth doing if you want to use the compost in a seed or potting mix.

Activity slows sharply and then stops as temperatures fall. Keep adding through winter if you like -- it will simply wait and restart in spring. Insulating a bin with straw bales or a thick layer of leaves extends the active season somewhat.

If year-round composting matters, that is the case for a worm bin indoors. Otherwise, plan on a spring restart and use the winter to accumulate browns.