Using Mulch
Amendment
Mulch is any material spread over the soil surface around plants, and it is one of the most useful practices in a home garden. Gardeners across the United States use it in vegetable beds, flower borders, around trees and shrubs, and along pathways. A layer of mulch works with the soil below rather than replacing it.
What it is
Mulches fall into two broad groups: organic materials such as shredded bark, wood chips, straw, shredded leaves, pine needles, and compost; and inorganic materials such as gravel, stone, and landscape fabric. Organic mulches break down over time and add organic matter to the soil, which can improve structure and the soil's ability to hold water. Mulch also helps moderate soil temperature, slow surface evaporation, and reduce weed growth by blocking light. Because organic types decompose, they need to be refreshed periodically, while inorganic types last longer but do not feed the soil.
What to do
Spread mulch in an even layer over moist, weed-free soil, and keep it a few inches away from plant stems and tree trunks so the base of the plant can stay dry and get air. Avoid piling mulch high against trunks in a cone shape, since this can trap moisture against the bark. Around trees, extend the mulch out toward the edge of the branches rather than concentrating it near the trunk. As organic mulch breaks down, rake it lightly and top it off to keep the layer at a useful thickness through the season.
Tips
Match the mulch to the job: finer materials like shredded leaves or compost suit vegetable and annual beds, while coarser bark or wood chips hold up well around trees and shrubs. Water the soil before and after mulching so moisture reaches the root zone rather than sitting only on the surface. For guidance on how much organic matter your soil needs and how to read a soil test, contact your local Cooperative Extension office, which can give recommendations tailored to your region and soil.
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.