A clump of comfrey is an organic gardener’s best friend. This useful herb is a repository of nutrients and minerals that can be used to fertilize your garden.
Comfrey is a perennial herb in the same family as borage. Like borage, it has hairy leaves so gloves should be worn when handling it. Comfrey flowers are downward facing bells like borage flowers and range in color from lavender to cream. The plants are very large, easily reaching 5 feet in height and up to 4 feet in width with leaves 12 to 18 inches in length. Comfrey has a long tap root, making it drought resistant. It grows best when well-watered, however. Thanks to that long tap root, it can be very difficult to get rid of once the plant becomes established. Any pieces of root left behind will grow another plant. The seeds are sterile in the variety most commonly used so it won’t self-sow in the garden. Neither does it have runners like tansy so comfrey will not take over your garden. The plants grow rapidly and should be divided every 3 to 4 years. Division is easy. Just take a shovel and drive it through the crown to make your divisions. Plant the pieces at least three feet apart. Comfrey grows best in full sun but will tolerate a little shade.
What makes comfrey so valuable to organic gardeners is its long tap root, non-fibrous leaves and fast growth. The tap root grows deeper in the soil than most plants so it can access minerals and nutrients not available to other plants. Those minerals and nutrients are stored in the leaves, which lacking fiber, break down easily and can be used in a tea for your plants, as a compost activator, as a mulch and as part of your potting mixture for containers. The fast growth of the plant allows it to be harvested every 5 weeks during the growing season.
Harvesting can begin when your comfrey plants are at least 2 feet high. Using gardening shears, a scythe or a sickle, cut the plants down to two inches above the soil. Within weeks, the plants will have grown back and be ready to be harvested again. You can continue harvesting your plants until fall when it is best to allow them to build up their winter reserves of nutrients. The plants die back completely in the winter and those nutrients flow back into the roots where they are stored until needed in the spring for the plant to begin growing again.
Comfrey used to be used medicinally but is now considered poisonous when used internally. It contains pyrrolizidine alkaloids which can build up in the liver over time eventually causing damage and even death.
If you are an organic gardener and inveterate composter like me, a patch of comfrey is a must-have. It is well-behaved, staying in the part of the garden where you have planted it but increasing in size each year so that you can divide your plants and expand your comfrey patch or share some with friends.