Comfrey is a large perennial herb growing to about five or six feet high and having large hairy leaves and cream, pink or blue bell-like flowers. The roots are long and bring up nutrients from deep within the ground. Its leaves are a source of potassium, phosphorus and nitrogen, which makes it very useful in the garden and especially in composting. Using comfrey in compost causes it to break down better and more efficiently. Each plant will produce about four to five pounds of leaves in a year.
Pick leaves of a comfrey plant once it has reached two feet high. It is not advised to take the leaves during the first year's growth. Cut a mature plant with garden shears to two inches above the ground and separate the leaves. After cutting it back, water it well by hose or watering can and place some mulch around the base of the plant. It will grow back in about five weeks.
Spread separated leaves over the top of a compost pile that is full of brown matter. Brown matter includes dead leaves and refuse from a garden, like the tops of carrots and radishes. Vegetable table scraps also can be placed in compost. The layer of comfrey leaves should be two to six inches thick.
Water down the pile with a garden hose until it is saturated. This helps the comfrey leaves start to break down and rot.
Dig up garden soil and cover the wet compost pile with a layer about one to two inches thick. This will help soak up the water and make the pile heat up a little faster. A warm compost pile rots faster than a cold one.
Leave the pile alone for about two weeks. The pile should heat up, encouraging microbes to start breaking it down quickly. After two weeks are up, turn the pile with a pitch fork or shovel then again two weeks later. By this time more leaves should be harvested and the process started over again. Leave the pile alone in winter, and the compost will become rich for the next year.
Start another compost pile the next spring or just add to the one already started. Start the process over once the comfrey is two feet high. Use compost from the bottom of the pile in the garden.