Comfrey

Overview

Comfrey grows a deep taproot and large, fast-growing leaves that break down quickly into rich mulch. Permaculture growers plant it around fruit trees and cut it several times a year. The Bocking 14 cultivar is sterile, so it doesn’t spread by seed.

History

Comfrey is native to Europe and western Asia. The Bocking 14 strain was selected in England in the mid-1900s by the Henry Doubleday Research Association for its vigor and because it doesn’t set seed.

Growing on Kauaʻi

• Likes moist, fertile soil and some relief from the hottest afternoon sun in the lowlands.
• Often grows more vigorously at cooler, higher elevations.
• Plant it where you want it to stay. Any small piece of root left in the ground will regrow, so it is very hard to remove later.

Planting and propagation

• Plant root cuttings 2–4 inches long, about 2 inches deep, or divide a crown into pieces with buds.
• Space plants about 2–3 ft apart, in a ring at the drip line of a fruit tree or in a dedicated patch.
• Make sure you are getting Bocking 14, not seeding common comfrey.

Care and maintenance

• Cut the leaves to a few inches above the ground whenever plants are about 2 ft tall, often 3–5 times a year.
• Water in dry spells and mulch around the crowns.

Role in the guild

Plant comfrey in a ring at the edge of a fruit tree’s canopy, such as avocado or citrus. It helps stop grass from creeping in, and each cutting feeds the tree’s roots. Pair it with pigeon pea for nitrogen.

Harvest

Cut leaves with shears or a sickle and lay them under nearby trees. They wilt and break down within a couple of weeks. Leaves can also be steeped in a bucket of water for a few weeks to make a liquid plant feed (it smells strong).

Uses

• Soil: fast-breaking mulch, compost activator, and liquid fertilizer.
• Bees: the flowers attract bees.

Important caution

Don’t eat comfrey or drink it as tea. It contains pyrrolizidine alkaloids, which can cause serious liver damage. Grow it for the soil, not the kitchen, and keep it away from grazing animals.

Problems to watch

• Spreading from root fragments if dug up or tilled.
• Struggles in hot, dry, full-sun lowland spots without water.

Learn more

• Plant Pono: Symphytum officinale assessment

General guidance for Kauaʻi; conditions vary by site. Check any new plant at plantpono.org before planting.