Comfrey in the Garden Emmalee Rolfe and Dan Drost
Summary Comfrey (Symphytum officinale) is a very hardy perennial herb adaptable to most conditions. Comfrey grows best in partial to full sun in moist, fertile soil. Comfrey is propagated by root cuttings or crown divisions. Comfrey can be planted throughout the growing season but establishes best when planted in the spring. Maintain moderate soil moisture, especially when plants are young. Once established, comfrey outcompetes weeds and does not have any reported insect or disease issues in Utah. Some leaves and roots are harvested after the first year of growth. It should be noted that consuming high doses or excessive long-term ingestion may cause liver toxicity, and those with known liver issues should consult a doctor before ingesting comfrey.
Varieties The two well-known varieties are common comfrey (often called true comfrey) and Russian comfrey (or Bocking 14). Common comfrey has cream or purple flowers, while Russian comfrey features blue or violet flowers. Russian comfrey is the variety of comfrey generally found in local garden centers.
How to Grow Soil: Comfrey is adaptable to most soil types but grows best in moist, fertile soil rich in organic matter, with a pH ranging from 6.0 to 7.0. Soil Preparation: Before planting, determine fertilizer needs with a soil test and follow the
recommendations given with the test report. Work the fertilizer into the top 6 inches of soil. If you fertilize with compost, apply no more than 1 inch of well-composted organic matter over the garden area fertilized. Propagation: Comfrey rarely produces seeds, so propagate new plants from root cuttings, crown divisions, or transplants. Root cuttings are the cheapest and most common propagation method. Root cuttings will develop buds in about 3–6 weeks, while crown divisions will emerge 10 days after planting. Planting and Spacing: Comfrey can be planted from April to September as long as the soil can be worked, but planting in spring is best. Root cuttings should be laid flat at 2–4 inches deep. Plant longer cuttings deeper than smaller cuttings. Crown divisions and transplants should be planted upright about 2 inches deep. Plant in a checkerboard arrangement with rows 2–3 feet apart. Closer spacing can result in higher yields. Water: Comfrey is not prone to drought due to its taproot and deep root system but still prefers moderate soil moisture. Water when the top 2 inches of soil are noticeably dry. Young plants need more frequent water during the establishment period. Fertilization: Comfrey needs adequate nitrogen, so ensure nitrogen levels in the soil are sufficient before planting. Comfrey requires regular nitrogen fertilization throughout the year. Use around 1–2 teaspoons (21-0-0) per square foot per month.