Comfrey (Symphytum sp.): a useful plant for your allotment or vegetable plot

Comfrey is a great plant to have as the flowers look not only pretty and are very attractive to bumblebees but it is also a good compost activator and can be made into liquid fertiliser as well.

Belonging to the Borage family (Boraginaceae), Comfrey has nodding tubular cream to purple-coloured flowers and big bristly leaves. The plant has a tap root which can access nutrients and water from deep in the soil. In the wild Comfrey likes to grow in damp places with rich soil such as in damp meadows, along river banks and ditches.
 

Common Carder bee visits Comfrey flowers

Several species are planted in gardens and allotments: Common comfrey (Symphytum officinale) and more commonly Russian comfrey (Symphytum x uplandicum) which is a hybrid between Symphytum officinale and S. asperum. To avoid the plants seeding around there is also a sterile variety of Russian comfrey available which is called Bocking 14. But I have to say that in the 3 years I have planted normal fertile Comfrey I have found only 3 seedlings which are easily removed when still young. Propagation is easy as you only have to divide a strong and healthy plant with a spade and replant the "offsets" with the growing points just below the soil surface.

A good place for Comfrey is the comosting area

Comfrey needs to be planted in a sunny position on fertile ground which never dries out completely in summer. A good place is around your composters as the Comfrey plants will absorb any liquid from your compost which drains into the ground and would otherwise be lost. It is a vigorous plant so give it enough space.

The leaves can be harvested several times a year and used as compost activator (mixed in with your composting material) or made into liquid fertiliser. You can also use the leaves as a mulch between your vegetables or fruit bushes where it breaks down quickly and releases nutrients into the soil. Comfrey is an excellent source of potassium and is great to use for flowering and fruiting plants.

Here is how I make my Comfrey fertiliser:

1. Fill a bucket, dust bin or any other watertight container with Comfrey leaves nearly up to the top (you can also mix your Comfrey leaves with nettle leaves to make a more nitrogen-rich fertiliser).
2. Fill the container up with water, stir well and cover with a lid.
3. For the next 3-5 weeks stir well every 2-3 days. You will see some foam and bubbles rising and after a few days it will start to get quite smelly. As warmer the weather as more quickly the leaves will break down.
4. Once the Comfrey-water mix turned into a thick dark liquid your fertiliser is ready to use.
5. Dilute the Comfrey fertiliser 1:10 with water (1 part fertiliser, 10 parts water) before using it, otherwise you will burn the leaves and roots of your plants. Also as a general rule never use fertiliser on dry soil, water first before you apply the fertiliser.

Comfrey fertiliser is a great natural and cost-free source of nutrients for your plants and it helps with maintaining healthy soil.

A nectar-robbing Buff-tailed bumblebee

The Comfrey flowers are very attractive to bumblebees so always leave some of your plants to flower. The long tubular flowers can only be pollinated by long-tongued bumblebees such as the Garden bumblebee (Bombus hortorum) but cheeky short-tongued bumblebees such as the Buff-tailed bumblebee (Bombus terrestris), which can not access the flowers in the normal way, have found a way around it and are often robbing the nectar trough a little hole they bite into the base of the flower near where the nectar is stored. Once the hole is there it will be used by other nectar-loving insects such as honeybees and wasp.

So next time have a closer look at Comfrey flowers and if you see a little hole near the base of the flowers you will know that nectar robbers have been active.

A Garden bumblebee accessing the flowers in a normal way