Comfrey (Symphytum) is an important herb revered for its medicinal properties.

It cannot be used internally because of alkaloids found in the leaves and roots that could cause liver damage. However, it is safe to use topically as the alkaloids are not absorbed through the skin. This plant species contains allantoin, a protein which is a hormone-like substance that stimulates cell division. Leaf and root poultices are used for healing wounds, burns, sore joints, dry skin and broken bones.

As a hardy perennial, comfrey will grow in moist areas and has the ability to clean and extract nutrients from stagnant water. A long tap root that can be three metres or longer enables the herb to accumulate such minerals as potassium, calcium, magnesium, iron, and phosphorus from the soil. Fresh or dried comfrey leaves have .75 per cent nitrogen, .25 per cent phosphorous and 0.2 per cent potash, which make them good for a fertilizer and even compost accelerator.

To make a compost tea, place a big handful of leaves in a bucket with enough water to cover them, and put a lid on it. In warm weather, the tea will be ready in about two weeks, after which the leaves should be squeezed out and then put in the compost pile. The liquid is then strained and used at a rate of one-third of a cup comfrey juice to one gallon of water, as a foliar feed and soil drench around plants. This is an excellent fertilizer, due to the potash content for tomatoes, peppers, cucumbers and potatoes.

Comfrey 'Axminster Gold'. Comfrey is easy to grow; too easy if the common variety is planted because it is invasive, self-seeding and spreading all over. But there are some ornamental forms with the same bold hairy leaves and petite bell flowers of rose, purple or white that are well behaved. They all like a moist soil in full sun or part shade, although the creeping form will tolerate dry and shady conditions.

Creeping comfrey (S. grandiflorum) is a low maintenance ground cover that reaches only 30 centimetres high, with creamy yellow flowers and crinkly leaves. It is a good choice for the dry shady north side of a house and is dense enough to choke out weeds.

'Goldsmith' comfrey is a dwarf variety and a less invasive type that has light yellow flowers and green and yellow variegated leaves. Growing to 15 to 20 cm tall, it forms a nice little clump of textural interest in the garden.

S. uplandicum 'Axminster Gold' is a Russian variegated comfrey that is tall at 1.2 to 1.5 m, and spectacular with dark green leaves edged in creamy yellow. This one doesn't tend to travel and after it flowers, the plant can be cut back to produce more foliage. 'Axminster Gold' is rust resistant, which tends to affect comfrey, but it may suffer from possible powdery mildew.

Divide comfrey in spring and ensure there is enough room for air movement between plants to prevent disease.

Contact Judith with gardening questions at lavendercottage. rogers@gmail.co m.