Compost is a fantastic soil amendment that helps improve soil structure, promoting air flow while retaining moisture. Adding compost as a soil amendment will depend on the type of plant bed or container.
For Annuals, Groundcovers, Shrubs or Trees:
Integrate compost into the top 3 to 5 inches of soil. While gardeners used to recommend adding compost to a tree or shrub hole, it is no longer recommended because it can impact root growth.
Add several inches of compost to the bed in the fall and till it in the spring. When you plant, add compost into the hole. You can also sprinkle a half-inch layer around the plant.
Mix 1 to 2 inches of compost into the top 6 to 8 inches of annual and perennial beds in the spring.
For Potted Plants:
Add 1 inch of compost twice a year. You can also create your own potting soil using 2 parts compost to 1 part sand or perlite.
For Lawn or Turf:
When planting a new lawn, add 1-2 inches of compost over the entire lawn area. Then incorporate it into the top 5-7 inches of soil for a mix of about 30% compost, 70% soil. On existing lawns, use compost in “bald spots” for replanting, or rake a ½ inch layer into the grass.
Mulch & Top Dressing
Mulch has many benefits to soil. It retains moisture, protects from erosion and compaction, deters weeds from growing, and keeps temperatures steady. Compost, when used as mulch, will provide all of these benefits – and it will add nutrients to the soil as it decomposes.
When using mulch, spread a layer of about 1-3 inches over the surface of the soil and use a rake to distribute it evenly. Lighter mulches made from leaves and plants will be less likely to weigh down the soil and can be added in thicker layers. Make sure not to add mulch in a “volcano” form around the tree trunk or plant stem. Leave a ring of mulch-free space around tree trunks to prevent fungal decay.
Compost tea is a liquid fertilizer that has extracted and concentrated the microbe population found in compost. To make it, compost is added to water, and then “food” and oxygen is added to stimulate bacteria and fungi growth. When compost tea is sprayed on plants, even in a small amount, those microorganisms help to fight off harmful bacteria and protect plants from disease.
To apply compost tea, spray the soil. Alternatively, spray plants every two weeks until the peak of the growing season.
Compost adds macronutrients, bacteria, and fungi to potting mixes that traditional commercial fertilizers do not contain.