Although comfrey is a fairly easy plant to grow and keep happy, you can improve the plant yield, health, and the ease of care if you spend a little time considering the best situation for your comfrey bed.
A healthy comfrey plant will live 20 years or more, and it’s not the easiest plant to remove once established, so site selection requires careful consideration.
Consider the uses you’ll make of your harvest, and try to locate your permanent comfrey bed as close as possible to where you’ll be using it.
For most of us that means locating it in or near our vegetable gardens or allotments, especially if your primary uses will include making liquid fertiliser, composting, and mulching.
Any consideration is how you will feed your comfrey – for an optimum crop you need to feed heavily with manure, so easy access is important for larger beds. Depending on your source of bulk organic matter you might want to allow trailer or other vehicle access to minimise the distance wheelbarrows of manure need to be moved.
Frost is generally not a consideration in the UK for comfrey, even frost pockets. Our temperatures do not reach levels that will trouble comfrey over-winter, and if you apply a good mulch of organic matter in the autumn your plants will be protected against any marginal frost damage. A sharp late frost can check spring growth but will not kill or permanently damage comfrey plants.
Comfrey will grow well in almost any soil-type and situation, but if you have a choice of site these are the ideal characteristics:
- In deep, free-draining soil. Both very light sandy soils and heavy clay soils can be improved for comfrey with the regular application of manure or other humus-rich material, and the fostering of the earth-worm population.
- Comfrey will not grow well on very shallow soils on a rock base, in this case you would be better growing comfrey in pots.
- Full-sun is ideal. Comfrey will perfom well in partial shade, an tolerably in heavier shade.
- Weed-free – in time comfrey will out-compete most common weeds, including common couch, but should be planted and established in weed-free soil. The regular application of mulches that help comfrey to thrive also defeat most weeds.
- Not in grass sward – grass is too competitive for nitrogen and will stunt growth. If growing in grass, for example in an orchard, clear a small bed for the comfrey, and/or mulch heavily around the plant base. Once mature the comfrey plant’s own growth can be used as a mulch and a fertiliser, and should be sufficient to keep the sward at bay around the base of the plant.
- Not directly under trees of any size or likely to completely shade your comfrey. Trees will rob the plants of sunlight and moisture, resulting in poor growth and plant health. Comfrey will grow well beneath the edge of the drip-line of mature trees provided sward is kept at bay (see above).