Comfrey

Comfrey (Symphytum officinale) is a fast-growing, rugged perennial herb native to Europe and Asia. Long celebrated by gardeners and herbalists alike, it is famous for its deep roots, medicinal history, and powerful role in organic gardening.

1. It Was Nicknamed "Knitbone"

For over 2,000 years, comfrey has been utilized in traditional medicine. The botanical name Symphytumcomes from the Greek word symphyo, which means "to unite". Its roots and leaves were historically used in poultices to treat sprains, bruises, and broken bones.

2. It Acts as a Natural Fertilizer

Comfrey is a "dynamic accumulator" plant. It possesses a thick, deep taproot—often reaching up to 6 feet deep—that extracts essential soil nutrients (like nitrogen, phosphorus, and potassium) that are typically out of reach for other plants. Gardeners often harvest the leaves to steep in water, creating a nutrient-dense liquid plant food, or chop them directly into compost piles as an activator.

3. A Nectar Hotspot for Bumblebees

Comfrey’s drooping, bell-shaped flowers (which range from purple and pink to cream) bloom from late spring into autumn. Because they are tubular, these flowers are primarily accessible to long-tongued insects, making the plant a favorite foraging ground for bumblebees.

4. It Should Never Be Eaten

Despite its historical use as a traditional green and medicinal tea, modern health organizations—including the UK NHS and the FDA—strongly advise against ingesting comfrey. The plant contains toxic compounds called pyrrolizidine alkaloids (PAs) that can cause severe, potentially fatal liver damage. Today, comfrey is strictly relegated to topical ointments and creams.

5. "Bocking 14" is the Gardener's Strain

In the 1950s, British researcher Lawrence Hills evaluated 21 different strains of comfrey at trial grounds in Bocking, Essex. He discovered that the strain "Bocking 14" was the most nutrient-rich and, uniquely, a sterile variety. Because it doesn't spread aggressively by seed, it remains the gold standard variety for gardeners to propagate via root cuttings today.