Russian comfrey (Symphytum x uplandicum) z5
Russian comfrey is a vigorous, deep-rooted, herbaceous perennial. It is grown to provide a supply of cut foliage rich in plant foods, especially potash. Comfrey leaves can be added to a compost heap as an activator, applied to the around plants to provide nutrients and used to make a liquid feed.
Bocking 14 is the variety of Russian comfrey most commonly grown for garden use. It has large, hairy leaves and purple, tubularproduced on tall stems. Plants may reach a height and spread of up to 1m (3-1/4ft). Its substantial tap root can reach 3m (10ft) underground. This crop can be harvested up to five times during the growing season and it will still grow strongly again.
Bocking 14 does not set seed and is propagated by offsets or root cuttings. Plants and cuttings may be purchased during the growing season; they are not sold when the plants are dormant. For an average garden, start with around six plants.
Choose a permanent site for your comfrey bed, preferably in full sun. It is not advisable to move comfrey too often as every bit of root left in the ground will regrow.
Spring is the best time for planting but any time during the growing season will do. Before planting, remove all perennial weeds and feed the soil well with manure or nitrogen-rich fertilizer. Plant the comfrey at a spacing of 60-100cm (2 — 3-1/2ft) each way. Offsets should be planted with the growing point just below the surface of the soil and root cuttings approximately 5cm (2in) deep.
Mulch comfrey with animal manure every couple of years, or feed it with a pelleted poultry manure and mulch with leafmould. In the first year, remove the flower stems but do not harvest the foliage.
Once they are established, comfrey plants can be cut four or five times a season. They will yield approximately 2kg (4—1/21b) per plant at each cutting.
Cut approximately 5cm (2in) above soil level when the foliage is around 60cm (2ft) high, before the flower stems start to show. It is advisable to wear garden gloves when handling comfrey as in some cases the hairy leaves can irritate the skin.
To allow sufficient regrowth before the winter, the last cut should take place no later than early autumn.
Comfrey leaves, rich in nitrogen and low in fibre, decay quickly to a black liquid. They have a variety of uses.
- As a compost activator — mix comfrey leaves with more fibrous compost ingredients to add goodness and start the composting process.
- For a liquid feed — comfrey leaves make a rich liquid feed, suitable for .
- As a fertility mulch — use comfrey leaves to mulch-hungry feeders such as blackcurrants, potatoes and . Do not use on acid-loving plants.
- To feed potatoes — place a layer of comfrey leaves 2.5-5cm (1-2in) deep in the bottom of a potato trench and cover the leaves with soil before planting potatoes.
- As a growing media ingredient — when they are mixed with 2-3 year-old leafmould, cornfrey leaves decay to form comfrey leafmould, which makes an excellent base for growing media:
Comfrey leaves can be used to make a concentrated liquid and a dilute form. The concentrate can be stored for longer than the dilute form and does not smell so strongly. Use it diluted with 10-20 parts water. A 45 litres (10gal) container should produce about 2.5 litres (4-1/2pt) of liquid, but smaller quantities can be made in a large plastic drinks bottle.
Analysis of comfrey concentrate
Nitrogen (N) 79mg/litre; Phosphorus (P) 26.4mg/litre; Potassium (K) 205mg/litre.
A plastic container such as a water butt with a cover; some bricks; cornfrey leaves; a collection vessel, minimum size about 1 litre (1-3/4pt). If making the liquid outdoors, use a vessel with a narrow neck to keep the rain out.
Drill a hole about 6mm (3/4in) in diameter in the bottom of the container. Put the container on a pile of bricks and pack in the comfrey leaves tightly. Replace the lid and put the collection vessel under the hole. Alternatively, cut the bottom off a plastic bottle and stuff it full of comfrey leaves. Remove the cap and invert the bottle in a container. After 2-3 weeks a dark liquid will start to drip from the container, and this may continue for a week or more.
Store the liquid in a cool dark place. Do not seal tightly as it can ferment in warm weather. Add the residue — the tougher fibres in the leaves — to the compost heap.