Green Materials (Nitrogen)
Material
Green materials are compost ingredients that generally supply nitrogen and moisture to the pile. They help feed the microbes that drive active decomposition. Common examples include fresh plant trimmings and fruit and vegetable scraps.
How it works
Nitrogen supports microbial growth, especially when paired with carbon-rich brown materials. Greens tend to break down quickly and can make a pile heat up if enough oxygen is present. Because many green materials are moist, they can also raise the overall water content of the pile. Too many greens in one area may create dense, wet pockets that limit airflow.
Details
Mix greens with browns as you add them so wet material does not clump together. Bury food scraps or cover them with browns to reduce odors and discourage pests. Spread grass clippings or similar fine materials in thin layers rather than thick mats. If the pile becomes slimy or smells sour, rebalance it with dry carbon-rich material and turn it.
Tips
Collect greens regularly and add them in manageable amounts instead of in large loads. Variety helps because different materials break down at different rates. A pile that stays wet and compact usually needs more browns and better mixing.
General guidance for US home gardens. For local guidance and any rules on composting, contact your Cooperative Extension office. Page updated Aug 4, 2026.