Sustainable Gardening

Coming soon!

Composting 101, The Basic Course

Compost is a great elixir for soil and plants. Here are some of the things compost does for your plants. It increases tiny air pockets in soil, pores that let plants soak up water and provide air for roots. Compost holds 80 to 90 percent of its weight in water, which helps make it available when plants get thirsty. It contains beneficial soil organisms and nutrients that feed plants, moderates the pH level by buffering the soil, and slowly releases nutrients over a long time period.

There are two kinds of composting – piles carefully built, wetted and turned - and the lazy approach, known as Let it Rot composting. In the first kind, the idea is to layer greens and browns until you have a pile a few feet high. The most common greens are fresh lawn clippings, newly pulled weeds, kitchen scraps, coffee grounds, and animal manures - but not cat or dog feces. The common browns are leaves, tea bags, straw, dried weeds and dried grass. Sawdust and wood shavings are also browns, but they take a long time to break down. It’s also important to thoroughly wet them. A compost pile should be consistently damp, like a wrung-out sponge. The other ingredient is oxygen and it’s important to turn the pile once a week or so. With a pitchfork or shovel, create a new pile so what was on top will be on the bottom. When done correctly, the temperature of the pile may reach 140 to 160 degrees within 24 to 36 hours, which is ideal for killing disease and weed seeds that might be in the pile. Covering the pile with a tarp is a way to keep moisture in the pile, and it’s good to keep the pile, bin, or tumbler in the shade to lessen moisture loss. In the lazy compost method, you mix the materials, wet it adequately, and keep the pile damp but turn it less. It will rot much slower, in perhaps a year or two, but you will get compost eventually.

Lee W. Miller
UC Cooperative Extension Master Gardener

Excerpted from UCCE’s Field Notes, Vol. 5, No. 2