15 Questions and Answers About Composting

Do I need a bin to make compost?

No, organic matter will eventually decompose without human help. But a container of some sort will keep your pile neat, protect it from the weather and pests, and make the job of tending it much easier.


Where is the best place to put a compost pile?

Pick a sheltered spot, out of the full summer sun if possible. Avoid trees and shrubs that may push their roots up into the pile. And give some thought to both convenience and appearance in choosing a location.

What is the "easiest" way to compost yard wastes, and food wastes?

Woody or "brown" yard wastes, like tree trimmings and autumn leaves, can be shredded and used as mulch around plants and on paths. Eventually they'll return to the soil. Food wastes, as well as green yard wastes like vegetable tops and grass clippings, can be dug into the ground. Use larger-scale "soil incorporation" only where you won't be planting for a few months.

Can I compost in the winter?

Even research teams on the South Pole have composted their garbage successfully! You can retain heat a little longer in the fall by covering the pile and insulating the container, perhaps with bags of leaves. Increasing the amount of "green" or using a compost activator may help keep the temperature up. Keep adding to the compost through the winter: it may not seem to be doing much, but the frozen materials will quickly finish breaking down when spring comes.


What if the pile has an odour?

An earthy scent is normal and inoffensive, but a well-built compost shouldn't produce unpleasant odours. If it does, your problem is either too much "green" stuff (ammonia smell) or too little air (rotten-egg smell). First, aerate the pile. If the odour persists, turn and rebuild the pile with more "brown" materials.


Should I wear gloves to handle compost?

If you haven't composted pet manures, which contain bacteria harmful to humans, there is no need to wear gloves. Finished compost can be handled just as you would garden soil.


How can kitchen wastes be stored for later composting?

Collect food scraps in a plastic container in the fridge or freezer, if you have space... or keep a tightly lidded container handy, covering each addition of compostable food wastes with just enough peat moss or sawdust to control odours.


Should I add ground limestone, soil, or fertilizer?

A perfectly good compost pile can be built out of nothing fancier than leaves and grass clippings. Lime will balance out the pH of a pile of highly acidic materials, like pine needles. However, most compost is naturally close to neutral in pH by the time it is ready for use. A scattering of soil should be added if your compost isn't in contact with the ground, because it is the soil organisms that do the decomposing work. With a variety of ingredients, fertilizer is seldom necessary.


What if the compost pile doesn't heat up?

The odds are that an inactive compost pile just doesn't have enough "greens" in it to start its temperature rising. The answer is to rebuild the pile with more high-nitrogen materials or a "starter" like manure "tea." That will probably solve the problem, but also check that the pile is as moist as a wrung-out sponge.


How do I compost with too many high-nitrogen materials?

You can dig extra "greens" directly into the soil, store some in a freezer or sealed container, buy peat moss to mix with it, or, as a last resort, dry some in the sun to decrease the nitrogen content. Perhaps a composting neighbour can use a donation?


How do I compost with too many high-carbon materials?

This is often a problem in autumn, when there's no shortage of dead leaves. If you have space, bag some and store them for covering up the food scraps you'll add through the winter, or for spring and summer when "browns" are harder to find. Bags of leaves also make insulating windbreaks for compost bins. Or moisten the leaves and store them in sealed bags to begin decomposing. In spring, add them to the compost. Mulching is another alternative, but shred the leaves finely, and again, a composting neighbour might be able to use your surplus.

When is compost "finished" and safe to use?

When an active compost pile fails to heat up once more, and very little of the original material can be recognized (perhaps an eggshell or the shapes of old leaves), the compost is ready to use. It will be the rich brown colour of good soil and smell something like the humus of a forest floor.

Does it need to be sterilized or screened?

Compost doesn't need to be sterilized or screened for the garden. For use indoors, it should be put through a strainer or quarter-inch screen and sterilized in the oven for 1 hour at 95^oC (200^oF). You will probably want to screen the compost you use to topdress the lawn as well.


Do I need to fertilize if I use compost?

The nutritional value of compost depends on the materials that were used to make it. That's why it's important to put as much variety into the pile as possible. If you're trying to enrich a severely depleted garden plot, or growing plants like peonies that demand a lot of food, you might want to add some commercially produced organic fertilizer. Soil testing is a good idea in this case. For most gardens and flower beds, however, compost provides a concentrated source of balanced nutrients as well as the organic matter the soil needs to store them.


What if I make too much compost?

It's hard to imagine such a situation! The earth can use all the organic matter you can give it, and you can apply compost at any time of year. Dig it into flower beds, layer it over a vegetable garden, or spread it under a tree to feed the roots. Finely screened compost can be scattered over a lawn, or sterilized and mixed with potting soil for house plants. And you can store compost in a bag or holding pen, as long as it is well protected from rain, wind and sun.