Growing Comfrey in Pots and Containers

Benefits of Growing Comfrey in Containers

Control Spread

Comfrey, particularly Bocking 14, can spread through root fragments. Container growing completely eliminates this concern by keeping the roots contained.

Flexibility of Placement

Containers allow you to position comfrey exactly where you need it—near your compost pile, adjacent to vegetable beds, or in any location where you'll use the harvested leaves.

Urban Gardening

No garden? No problem. Containers make it possible to grow this valuable permaculture plant on balconies, patios, rooftops, or any small outdoor space with adequate sunlight.

Controlled Growing Environment

Container growing gives you more control over soil quality, drainage, and nutrients, which can be especially beneficial in areas with poor native soil.

Choosing the Right Container

Container Size

Comfrey develops a deep taproot and substantial root system, so container size matters:

• Minimum size: 5 gallons (approximately 12 inches deep and 12 inches in diameter)
• Ideal size: 10-15 gallons (15-18 inches deep and 15-18 inches in diameter)
• For maximum growth: 20+ gallons

Remember: The larger the container, the more biomass your comfrey will produce and the less frequently you'll need to water.

Container Material

Several materials work well for growing comfrey:

• Plastic: Lightweight, inexpensive, and retains moisture well
• Fabric pots: Excellent drainage and air pruning of roots, but may require more frequent watering
• Ceramic or terracotta: Attractive but heavy and can crack in freezing temperatures
• Wood: Aesthetically pleasing but will deteriorate over time

Drainage

Regardless of material, ensure your container has adequate drainage holes. While comfrey likes moisture, it will rot if left in standing water.

Soil Mix for Container Comfrey

The ideal soil mix for container-grown comfrey should be:

• Rich in organic matter
• Moisture-retentive but well-draining
• Slightly acidic to neutral pH (6.0-7.0)

Recommended Soil Recipe

A good basic mix for comfrey containers is:

• 60% high-quality potting soil
• 20% compost
• 10% aged manure (optional)
• 10% perlite or pumice (for drainage)

Avoid using garden soil in containers as it can compact over time and may contain weed seeds or pathogens.

Planting Comfrey in Containers

Best Time to Plant

The ideal times to plant comfrey in containers are early spring and early fall, when temperatures are moderate and the plant can establish before extreme weather.

Step-by-Step Planting Process

1. Prepare your container: Ensure it has drainage holes and fill it about 2/3 full with your soil mix.
2. Position your comfrey: If planting a crown or potted plant, place it so the crown will be 1-2 inches below the soil surface when finished. If planting root cuttings, lay them horizontally about 2-3 inches deep.
3. Fill with soil: Add the remaining soil mix around the plant, gently firming it down.
4. Water thoroughly: Water until it drains from the bottom of the container.
5. Position the container: Place in a location that receives at least 4-6 hours of sunlight daily.

Caring for Container-Grown Comfrey

Watering

Container comfrey requires more frequent watering than garden-grown plants:

• During active growth: Water when the top 1-2 inches of soil feels dry
• Hot weather: May need daily watering
• Winter: Reduce watering significantly when plant is dormant

Consistent moisture is key—comfrey in containers can dry out quickly, especially in hot weather.

Fertilizing

Unlike ground-grown comfrey, container plants can't access nutrients from deep in the subsoil:

• Apply compost tea or diluted liquid organic fertilizer monthly during the growing season
• Top-dress with compost in spring and mid-summer
• Avoid high-nitrogen fertilizers, which promote leaf growth at the expense of root development

Mulching

Apply a 1-2 inch layer of organic mulch (like straw or shredded leaves) to the soil surface to:

• Conserve moisture
• Moderate soil temperature
• Slowly add nutrients as it breaks down

Harvesting Container Comfrey

When to Harvest

Container-grown comfrey can be harvested using the same guidelines as garden plants:

• Begin harvesting when the plant is well-established (usually after 3-4 months)
• Cut leaves when they're fully developed but before flowering for maximum nutrients
• Leave at least 2-3 inches of growth above the crown
• Expect 3-4 harvests per season from a healthy container plant

Harvest Volume

Container-grown comfrey typically produces less biomass than garden-grown plants, but with proper care, a large container (15+ gallons) can yield 2-3 pounds of leaves per harvest.

Overwintering Container Comfrey

Comfrey is cold-hardy in USDA zones 4-9, but container plants are more vulnerable to freezing temperatures because the roots don't have the insulation of the ground.

Winter Protection Options

• Zones 7-9: Container comfrey can usually remain outdoors year-round with minimal protection.
• Zones 5-6: Move containers to a sheltered location (against a building) and wrap the container with bubble wrap or burlap for insulation.
• Zones 4 and colder: Move containers to an unheated garage, shed, or basement where temperatures stay above freezing but below 45°F to maintain dormancy.

Winter Care

• Cut back all foliage after the first frost
• Reduce watering significantly, keeping soil just barely moist
• Apply a thick layer of mulch over the soil surface
• Resume normal care when new growth appears in spring

Repotting and Dividing

Container comfrey will eventually become root-bound and need attention:

• When to repot: Every 2-3 years, or when growth slows significantly
• Best time: Early spring just as new growth begins
• Process: Either move to a larger container or divide the plant and repot in fresh soil
• Root pruning: If keeping the same container size, trim up to 1/3 of the roots before repotting

Division is an excellent opportunity to propagate new plants from your container comfrey.