Comfrey is a fairly humble looking plant. It has large hairy green leaves and small bell-shaped flowers, typically colored either purple or white. However, what it may lack in striking appearances, it certainly makes up for in the myriad benefits it can give to a permaculture plot.
Comfrey is arguably the best ‘cut and leave’ mulch – also called ‘green manure’ available to the permaculture gardener. It grows quickly, so you can often get three separate growths over a single season suitable for cutting and leaving on the soil. It has a wide array of important chemical and minerals that it adds to the soil as it decomposes, including silica, magnesium, calcium, iron and potassium. Best of all it is loaded with nitrogen, the most important chemical element in all plant growth. Not only does this nitrogen enter the soil from where other plants’ roots can access it for growth and crop development purposes, it also means that when the cut comfrey is decomposing it doesn’t pull whatever nitrogen is already in the soil out to aid the decomposition, which mulches that are high in carbon, such as straw, can do. The range of elements that comfrey supplies as a mulch means that it is suitable for placement around almost every plants, particularly benefiting vegetable and fruit species – which are likely to form the majority of plant life on a permaculture plot.
The nutrients in comfrey and its rapid rate of composition make it an ideal addition to the compost pile, particularly if you are hot composting, The high levels of nitrogen serve to activate the compost and helps to break the material down more quickly – which is particularly useful if you have a lot of brown material in your compost, such a branch prunings, which take much longer to break down than green material such as grass clippings and vegetable scraps. Add comfrey to you compost throughout the pile, rather than in a single layer, to get the maximum, and quickest, benefit. Indeed, you might consider siting your comfrey next to the pile so you can add a few leaves every time you add material to the compost.
When planting out seedlings of seeds of other plants, it can be very beneficial to add freshly cut comfrey leaves to the planting hole. The leaves break down quickly, giving the juvenile plants a big dose of nutrients to help them establish themselves. Shredded leaves are also a good addition to potting mix for container planting. But comfrey is arguably even more effective as a fertilizer in liquid form. A liquid fertilizer – or ‘tea’ – made from comfrey is an excellent addition to all plants, but is particularly useful for stressed or damaged plants, giving them a rehabilitative nutrient boost. In a liquid form, the nutrients in the comfrey are immediately available to the plant roots; they do not have to wait for leaves to decompose before being able to access them. Simply place comfrey tops and leaves in an old container, such as a bucket with a hole in the bottom and a small container underneath. Weight the leaves down with a brick or similar item, and over several weeks the comfrey will decompose to a thick black goo that drips into the container. Dilute this goo at a ration of approximately one part comfrey liquid to fifteen parts water and apply liberally to the garden where required.
It is not only when it has been cut back that comfrey benefits the permaculture garden, it is very useful when it is growing as well. Comfrey has a large, black root that penetrates deep into the soil profile. This allows the plant to access nutrients in the soil that are beyond the reach of shallower rooting plants. It brings these nutrients up to the topsoil, making the growing medium richer. These extra nutrients are also returned to the soil if the comfrey is subsequently cut as mulch, added to compost or used as fertilizer. The deep roots of the comfrey plants also improve the soil’s structure. They provide channels through which moisture can percolate, and air can circulate. The loosening of the soil that comfrey roots cause also makes for a better environment for soil organisms that in turn decompose the comfrey leaves that fall or are cut back into the soil.
If you have problems with running grasses, comfrey can be a very effective weed barrier. You need to have a stop several plants wide and ensure that you are using non-seeding varieties so that the comfrey itself does not run riot, but this can be an effective way of keeping grasses out of particular areas, particularly orchards.
Bees are readily attracted to comfrey flowers, so the plant can be useful in attracting these beneficial insects to your plot. The leaves of the plant can also be fed to livestock, including chickens. However, it is advisable to feed in small quantities, as comfrey does contain certain alkaloids that if accumulated too much can cause toxicity problems in grazing animals.
With so many benefits, it is easy to see why almost any permaculture plot would benefit from the addition of comfrey. If you want to cultivate some for use on your site, plant it in a permanent position, as it can last a long time, and keep providing you with leaves for mulch or compost over many years. It prefers full sun but can survive in partial shade, and like a well-drained, loose soil. Composting helps establish the plant, and needs regular watering (although you should avoid waterlogging, as this inhibits growth). A great thing about growing comfrey is that the more you pick the leaves, the more they keep coming, so regularly trim your mature plant (it I ready to go from when it is approximately two feet tall). Regular cutting also prevents the comfrey from flowering, meaning all its energy goes into producing leaves, which is where all the beneficial nutrients are. Don’t worry about not having flowers for propagation, as comfrey is typically propagated by splitting its abundant roots.