Comfrey is a perennial herb that has many uses in the garden. It has a well-deserved reputation as a super plant amongst organic growers and permaculture practitioners. It’s a nutrient rich ‘chop and drop’ mulch and compost activator, helps to break up compacted soils with its’ thick tuberous roots, can serve as a barrier to spreading grasses and weeds, and the leaves make a potent plant based liquid fertiliser.
A Brief History of Comfrey
Native to Europe, comfrey has been grown and used for thousands of years by many cultures for medicine, fertiliser, and fodder. The wild variety, Symphytum officinale, grows from seed and isn’t as useful as the sterile Russian Comfrey cultivars. During the 1950’s, Britains’ best known organic gardener, Lawrence D. Hills, developed a hybrid version selected for its high yields. Based in the town of Bocking, his trials resulted in cultivars known as Bocking 1 through 14. He chose Bocking 14 as the most productive, disease resistant, and highest in potash. For these reasons, it is the most commonly grown variety today. Because Bocking 14 is sterile, it doesn’t produce seed and must be propagated by crowns or root sections, which is how it’s typically sold.
Comfrey has large, green, pointed leaves covered in hairs. It grows in a rosette up to 24-48” (60-120 cm) high and wide. If temperatures are cool enough, it produces a mauve, bell-shaped flower on a spike in clusters. In subtropical and tropical climates it may not flower. In cold regions, it is dormant in winter.
Comfrey is hardy from zone 4-9. It is fast growing, prefers full sun, but also grows in part shade, and yields the most leaves in a damp spot with lots of nitrogen. It’s drought-tolerant, but grows less vigorously without consistent water. Choose a location where it will grow continuously, as it can be hard to eradicate once established due to the roots that break off and set new plants when dug up. It requires deep soil without a hardpan or rock but can grow in heavy clay. Plant crowns or root segments 1” to 2” deep (3 – 6 cm) and keep well watered until leaves emerge. Once established, you can dig them up and cut the roots into segments to create many more plants.
Cut the lush, fast-growing leaves several times per season and use as mulch or side dressing under fruit trees or vegetables, especially potatoes. Add the leaves to compost to help speed up the composting process and to add valuable nutrients. To create a weed or grass barrier around vegetables or garden beds, plant in strips several rows wide. Make a liquid fertiliser by soaking the leaves in a bucket of water for a few weeks, then strain and use directly on plants, or stack the dry leaves in a bucket with a hole on the bottom under a weight, like a rock, to create a thick, black sludgy liquid. Dilute with water 15:1 before applying to plants. It’s also been shown to be an effective companion plant where it is just left to grow and cycle nutrients. Given its’ versatility, comfrey makes an incredibly useful addition to any garden. Look for it for sale from nurseries or online seed companies.
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