How to Propagate Comfrey: Complete Guide

Understanding Comfrey Propagation

Comfrey (especially Bocking 14 and other sterile hybrids) is propagated vegetatively, meaning new plants are grown from pieces of existing plants rather than from seeds. This ensures that the new plants are genetically identical to the parent plant, preserving the desirable traits of your specific variety.

The remarkable regenerative ability of comfrey comes from its high content of allantoin, a compound that stimulates cell proliferation and wound healing. This is why even small fragments of comfrey root can develop into new plants.

Propagation Method 1: Root Cuttings

Root cutting is the most common and economical method for propagating comfrey. It takes advantage of comfrey's ability to regenerate from even small pieces of root.

When to Take Root Cuttings

The best times to take comfrey root cuttings are:

• Early spring: Just as plants are beginning to emerge
• Late fall: After the foliage has died back

These periods coincide with when the plant is either entering or exiting dormancy, which minimizes shock to the parent plant.

Step-by-Step Root Cutting Process

1. Select a mature plant: Choose a healthy, established comfrey plant that's at least 2 years old.
2. Expose the roots: Carefully dig around the plant to expose some of the roots without completely uprooting it. Comfrey has deep taproots, so you'll only need to access the upper portion.
3. Cut root sections: Using clean, sharp pruners or a knife, cut 2-6 inch sections of root. Roots about the thickness of a pencil (¼ to ½ inch diameter) work best.
4. Prepare for planting: Root cuttings can be planted immediately or stored temporarily in slightly damp sand or sawdust in a cool location.
5. Plant horizontally: Lay the root cuttings horizontally in prepared soil, about 2-3 inches deep and 6-12 inches apart.
6. Mark the location: Since it may take several weeks for shoots to emerge, mark where you've planted the cuttings.
7. Water and wait: Water thoroughly and keep the soil consistently moist (but not waterlogged) until new shoots emerge, typically in 3-8 weeks.

Propagation Method 2: Crown Division

Crown division provides faster results than root cuttings and is an excellent way to get established plants quickly.

When to Divide Crowns

The best times for crown division are:

• Early spring: Just as new growth begins to emerge
• Early fall: When growth is slowing but before dormancy

Step-by-Step Crown Division Process

1. Select a mature plant: Choose a healthy comfrey plant that's at least 2-3 years old with multiple crowns.
2. Prepare the plant: A few days before division, cut back all foliage to about 2 inches above ground level to reduce transplant shock.
3. Dig up the plant: Using a sharp spade, dig a wide circle around the plant (at least 12 inches from the center) and carefully lift the entire root ball.
4. Divide the crown: Using a sharp knife or spade, cut through the crown to create sections, ensuring each division has both roots and at least one visible growing bud.
5. Trim if necessary: You can trim the taproot to about 6-8 inches long to make planting easier.
6. Replant immediately: Plant each division with the crown 1-2 inches below the soil surface, spacing plants 2-3 feet apart.
7. Water thoroughly: Water well after planting and keep soil consistently moist until new growth is established.

Propagation Method 3: Leaf-Bud Cuttings

This less common method can be used when you want to maximize the number of plants from limited material.

Step-by-Step Leaf-Bud Cutting Process

1. Select stems: Choose healthy stems with fully developed leaves.
2. Cut sections: Cut the stem into sections, each with a leaf and a small piece of stem above and below the leaf attachment point.
3. Prepare growing medium: Fill containers with a well-draining propagation mix (equal parts perlite and peat moss works well).
4. Plant the cuttings: Insert the cuttings into the medium with the leaf bud just above the surface.
5. Create humidity: Cover with clear plastic to maintain humidity.
6. Provide indirect light: Keep in bright, indirect light.
7. Wait for roots: Roots should develop within 3-4 weeks.
8. Transplant: Once roots are established, transplant to individual pots or directly into the garden.

Propagation Method 4: Seeds (Common Comfrey Only)

Important: This method only works with common comfrey (Symphytum officinale), not with Bocking varieties or other sterile hybrids like Bocking 14, which do not produce viable seeds.

Step-by-Step Seed Propagation

1. Collect seeds: Harvest seeds when they turn dark brown or black, typically 4-6 weeks after flowering.
2. Cold stratification: Place seeds in damp sand in a sealed container and refrigerate for 2-4 weeks to improve germination.
3. Sow seeds: Sow seeds ¼ inch deep in seed-starting mix.
4. Maintain moisture: Keep soil consistently moist but not waterlogged.
5. Provide light: Place in a location with bright, indirect light.
6. Wait for germination: Seeds typically germinate in 2-3 weeks.
7. Transplant seedlings: Once seedlings have several true leaves, transplant to individual pots or directly into the garden.

Caring for Newly Propagated Plants

Watering

Keep soil consistently moist (but not waterlogged) until new growth is well-established. Once established, comfrey is drought-tolerant but produces more biomass with regular watering.

Fertilizing

Comfrey generally doesn't require additional fertilizer, as its deep roots mine nutrients from the subsoil. However, a light application of compost when planting can help establishment.

Mulching

Apply a 2-3 inch layer of organic mulch around newly planted comfrey to conserve moisture and suppress weeds until the plants are established.

Protection

Mark newly planted areas clearly, especially for root cuttings, as it may take several weeks for shoots to emerge. This prevents accidental disturbance.