Image: kirstyhall,on Flickr
Organic Gardening has broken down how much compost to use in an easy to follow guide. Here is what they recommend:
New Garden Beds
First Application: If you plan on adding compost to a new garden bed 1 time throughout the season, till in 1 to 2 inches of finished compost. Work it into the soil about 4 to 5 inches deep. For new garden beds in areas with heavy rainfall or in the deep south, till in 2 to 4 inches of compost.
USDA Zones 4 or Colder: Areas in USDA zone 4 or colder have short growing seasons which means the garden has less time to utilize the finished compost. Gardens in these areas need less compost, only an inch for the first application and a ½ inch annually after that. Again, till the added compost about 4 to 5 inches deep.
Second + Applications: After the first application, garden beds only need a ½ inch of compost annually. Gardens in the south, areas with heavy rainfall or those with sandy soil will benefit from 1 inch of finished compost yearly.
Heavy Feeders: Some plants are heavy feeders and benefit from 1/4 inch of finished compost about midway through their growing season. (Consult a growing guide for specific vegetables on when to add compost) Rhubarb, corn, tomatoes and peppers are a few vegetables considered heavy feeders.
Succession Crops: If you plant succession crops, add 1/8 to 1/4 inch of finished compost to the soil before your second planting and so on. Adding this tiny bit of compost will get succession crops off to a healthy and productive start.
As you can see, a little compost really does go a long way. As the years go by after the first application is added, you’ll need to use less and less. Leftover nutrients, the one’s your plants were too full to consume, leach into the garden bed helping to keep it rich and fertile.
Additional Compost Articles
Reference: Organic Gardening (2007). Make Compost in 14 Days. Rodale Inc