6 Reasons to Grow Comfrey

Comfrey has very special properties that will benefit many areas of health and garden maintenance. It’s one of the most useful plants to have in the garden.

1. Compost accelerator

The most common use of comfrey is as a compost accelerator. Comfrey is high in nitrogen, so when added to brown leaves, which will be high in carbon, the comfrey will balance out the carbon-to-nitrogen levels and so speed up the composting process.

2. Free fertiliser

Comfrey is high in nitrogen, phosphorus and potassium – the three elements that make up most fertilisers – and contains many trace elements. It has a large and deep (up to 2m) root system that pulls nutrients from the subsoil into their leaves. When comfrey leaves decompose they turn into a liquid. When diluted with water this liquid makes an excellent foliar feed for the garden. (See the end of this article for the steps on how to make it.) You can also make leaf mould that can be used as a fertiliser or even a potting soil, but because comfrey decomposes into a liquid, you need to add other shredded leaves to the mix. The comfrey then acts as an accelerator.

READ MORE: Borage is also a great compost activator, read more about it here.

3. Organic mulch

With its high nutritional value, chopped up comfrey leaves are effective around plants as a mulch. This mulch will also be a distraction for snails and slugs, who love them. In a windy area, allow the leaves to wilt for a few hours and then dig them into the top 2cm of the soil. Comfrey leaves are high in phosphorous, making them a great food for fruit-bearing plants like tomatoes and peppers.

4. Planting tool

Line the bottom of a planting hole or a container with comfrey leaves to act as a slow-release fertiliser. They will impart nutrition as they decompose.

5. Repairer

Comfrey is known to support bark regrowth after damage. A poultice of comfrey leaves wrapped around the damaged bark could be a life saver for a damaged tree.

6. Pollinator

The purple bell-shaped flowers of comfrey attract all kinds of pollinators, such as beneficial bees.

Growing tips

• Comfrey is a hardy perennial that is a prolific leaf producer and so can be harvested often.
• It grows in full sun or shaded areas and makes the perfect plant to grow next to the compost heap.
• Find an area with lots of space so that the large root system can grow.
• Plant in any soil with good drainage.
• They are extremely cold-hardy plants that will become dormant in winter and shoot again in spring.
• No feeding of comfrey is needed.

Note: In this article we have stuck to the benefits of comfrey in the garden and not mentioned any health benefits. Comfrey contains allantoin, which is why it has been used in the past for healing bones, burns, sprains, bruises, bites and inflammation (hence comfrey’s common name of ‘knitbone’). However, it is also highly toxic and contains pyrrolizidine alkaloids that have been known to cause liver damage. Please be very careful when using comfrey for human treatments and consult a doctor before use.

How to make comfrey liquid fertiliser 

1. Drill a few holes in the bottom of a large container. Place this container in a bigger container to catch the liquid. 

2. Pack the first container with as many leaves as you can fit in it, and weigh them down with a brick or rock.  

3. Check regularly, but it should take 4 – 6 weeks for the leaves to break down into a dark nutritious liquid. 

4. To use, dilute the liquid (1 part liquid to 15 parts water) to use as a foliar feed for established plants. Make a weaker solution for young plants so that it will not damage the roots. 

It is also possible to mix the leaves with water, but this does create a rather strong odour. You can always add a lid to the container to keep the odour reasonable. This mixture will decompose quicker. Because it will already be diluted you can mix it with 3 parts water to use on the garden.