Probably the most popular use of comfrey, this simple process will produce a concentrated liquid plant food as good as any commercial organic alternative, for free. It does need a reasonable volume of comfrey plant material to get established in a large container – if you only have one plant you may get better results with pre-diluted comfrey tea, or creating a comfrey column.
- A suitable container, with a lid and possibly a drainage tap depending on its size. We use plastic blue barrels/drums, often freely or at least cheaply available in most locations. These are robust enough to not be affected by the weather and will last for many years.
- Containers for the finished feed – we use old milk cartons, orange juice bottles, etc.
- Cut comfrey – see our harvesting guide.
- A little patience.
The method is simple – stuff all of the cut comfrey in the barrel, attach the lid securely (a brick or two on top won’t hurt), and wait.
The comfrey will start to decompose within a few days, and within a few weeks a thick, dark liquid will collect in the container. This liquid will smell really bad – this is normal and expected.
You can collect this liquid as soon as it starts to be produced, but you will get better future results if you can leave all of the liquid in the container until you add the next crop of comfrey. This will break down much more quickly than the first, and you can start to bottle and use your comfrey feed.
Just keep topping up the container with any freshly-cut comfrey. Eventually, after several seasons, you may need to remove solid waste residue – this can be done with a garden fork or graip, and put into compost bins or a muck heap as an excellent activator.
Using comfrey feed
This method produces a strong, concentrated liquid comfrey feed. Do not use it neat!
It should be diluted between 1:10 and 1:20, depending on the use:
- For tomatoes: 1:10
- As a general purpose feed for vegetable and flower beds: 1:15
- As a foliar feed: 1:20
Do not over-use – the nitrogen in this feed is in a highly available form readily lost by leaching.
Storing comfrey feed
Use old milk cartons, orange juice bottles, or any other container with a tight-fitting lid. Store in a cool, dark place.
Some sources say to use within 12 months, we haven’t noticed any significant degrading of benefits if kept longer.