Comfrey fertiliser

Here's another natural fertiliser that's easy to make. You may have been cursing the comfrey for its vigour as you hacked it down once again, but quite apart from its usefulness it’s also a very attractive plant to have growing around your plot that attracts bees. If you're interested in producing natural fertilisers you may also find the post on nettle fertiliser of use.

Comfrey is a perennial herb with a black turnip-like root and large hairy broad leaves and produces small bell-shaped white, cream, light purple or pink flowers that attracts bees. It’s native to Europe and widespread throughout Ireland and Britain, growing in damp grassy places. Comfrey has long been recognised by both organic gardeners and herbalists for its great usefulness and versatility.

If your plant produces purple flowers then you have the “Bocking 14” cultivar of Russian Comfrey (Symphytum x uplandicum). This strain was developed during the 1950s and will not set seed, an advantage over other types since it won’t spread out of control. This variety is propagated from root cuttings.

If you’re developing your own comfrey bed don’t harvest leaves in the first season and remove any flowering stems so the plant focuses its energy on establishing itself. Mature plants can be harvested up to four or five times a year and are ready for cutting when about 2 feet high from mid Spring through to mid Autumn. Comfrey will rapidly grow again and be ready for further cutting about 5 weeks later. It’s best to cut shortly before flowering; this is when the plant is at its most potent for nutrients.

Harvest by using shears to cut to about 2 inches above the ground. Take care when handling and consider wearing gloves since the leaves and stems are covered in hairs that can irritate the skin. Stop leaf cutting after Autumn to allow plants to build up winter reserves. The leaves will die back and break down in winter and nutrients and minerals are transported back to the roots for use the following spring.

Comfrey is an excellent source of potassium, an essential plant nutrient needed for flower, seed and fruit production. Its leaves contain 2-3 times more potassium than farmyard manure.

There are various ways in which comfrey can be utilised as a fertiliser, these include:

Compost activator

Include in the compost heap to add nitrogen and help to heat the heap. Comfrey should not be added in quantity as it will quickly break down into a dark sludgy liquid that needs to be balanced with more fibrous, carbon rich material.

Liquid fertilizer

Weigh down a handful of leaves in a bucket of water, cover and leave to rot down for 4–5 weeks to produce a ready to use comfrey fertiliser. Alternatively put several bunches of leaves in a refuse bin and fill with water.

Mulch

A two inch layer of comfrey leaves placed around a crop will slowly break down and release plant nutrients; it’s especially useful for crops that need extra potassium, such as fruit bearers, but also does well for potatoes. Avoid using flowering stems as these can root.