Q. How can I speed up decomposition? A. Gardeners can step in and accelerate the composting process by creating optimal conditions for decomposition.
Get the balance right. Compost = Air + Water + 2 Parts Browns + 1 Part Greens
Shred, chop, or chip ingredients. Smaller pieces of material have more surfaces for microorganisms to work on, so your pile decomposes faster. Pieces ranging from 1/2 to 1 1/2 inches decompose best.
Have a critical mass. A pile will not heat up if it's too small. Minimum size is 3 by 3 by 3 feet.
Mix your ingredients. For a long time, experts (including—gasp!—this magazine) recommended piling up ingredients like a layer cake, but compost should really be more like a tossed salad—mixing all the goodies together produces the best results. "You definitely want to mix," says Dr. Cogger. "You want to get the green and brown material in intimate contact." Layer cake-style composting causes compaction and reduces biological activity.
Aerate your pile. Compost can be turned twice a week or never; it's up to you. But the more you turn it, the faster you'll get results.
Monitor moisture. Dry piles decompose slowly, so adjust moisture as needed.
Add some microbes. Mix in a shovelful of finished compost or garden soil to get the microbial activity rolling.
Q. What's the easiest way to make compost? A. Mix together green and brown yard wastes (remember the C/N ratio), place them in a pile, and wait 6 to 24 months for the microorganisms, earthworms, and insects to break down the material. Add new materials to the top of the pile. You can reduce the waiting period by occasionally turning the pile and monitoring its moisture level. Compost on the bottom of the pile generally "finishes" first.
Q. When is my compost finished? A. "If the pile isn't heating anymore and you can't identify original materials, it's done," says Dr. Maynard. It's okay to use compost that's not quite finished as mulch. You can also work it into garden beds one to two weeks before planting, because the soil microbes help finish off the decomposition process. Be sure to screen out any big, woody chunks first. If you want to use compost in a potting mix, it must be fully mature to prevent problems with nutrient availability and germination. Try this sniff test, recommended by soil scientists at Cornell University, to see if your compost makes the cut for potting mixes.
Mix some compost and water in a jar until the compost is soggy.
Seal the jar and wait a week.
Open the jar. If the compost smells bad, it's not done yet. If it smells earthy, then it's fine to use (though you may want to experiment with planting a small amount of seed first to be sure).
