Using Compost
Amendment
Compost is one of the most widely used soil amendments in American home gardens, and it can be made at home or purchased in bags and bulk. Gardeners across every USDA hardiness zone use it to build better soil in vegetable beds, flower borders, and around trees and shrubs.
What it is
Compost is the dark, crumbly, earthy-smelling material that results when leaves, grass clippings, kitchen scraps, and other organic matter break down through the work of microbes, fungi, and larger soil organisms. Finished compost holds moisture, improves soil structure, and helps sandy soils retain water while helping clay soils drain and loosen. It adds organic matter and returns a range of nutrients to the soil in slow-release form, and it supports the living community of organisms that make soil productive. Good compost is stable and mature, meaning the original ingredients are no longer recognizable and the material no longer heats up.
What to do
Spread compost as a layer over the soil surface and mix it into the top few inches of a bed before planting, or use it as a topdressing around established plants and as a mulch. It works well blended into the backfill of new planting holes and stirred into container and raised-bed mixes. Let homemade compost finish curing until it looks and smells like dark soil before you use it, since unfinished material can tie up nitrogen as it continues to decompose. When buying, look for a mature product and consider its intended use, since some blends are made for mulching and others for mixing into soil.
Tips
Because compost quality and nutrient content vary widely by source and batch, have your soil tested and let your local Cooperative Extension office help you interpret the results and decide how much compost to apply. Keep a working compost pile moist and turned, and mix greens such as fresh clippings with browns such as dried leaves to keep it breaking down evenly.
General guidance for US gardens. For specific nutrient, pH, and amendment rates, have your soil tested through your local Cooperative Extension office. Page updated Aug 4, 2026.