Composting with Comfrey

Compost Bins

New compost heap finished and topped off with cardboard.

I took a cut off the comfrey some of which was used as the activator in a new compost heap and a cheap new gadget that helps make compost.

Comfrey Cut

Took a cut off the established comfrey. Since the plants were mulched they’ve done much better without weed competition and I think next year will be in full growth. Used about a third of the cut in the building of a compost heap in the bin on the walled veg plot.


Building a New Compost Heap

Started with a layer of sweetcorn stalks to allow some airflow up into the heap followed by a layer of green material and then a layer of comfrey. Comfrey is rich enough to act as a compost activator. Then more green materials followed by another layer of comfrey and so on with the addition of a little lime to keep things sweet on the occasional layer.

The green materials have been building up for a while. There’s the mustard green manure that was cut from the plot under the poultry patch, green waste from polytunnel, annual weeds, hedge trimmings etc.

It’s light on brown materials but in my experience that doesn’t make much difference. I think people get too bothered about doing things ‘by the book’. I suppose that’s experience when you learn what rules you can bend, what rules you can break and what rules you really must follow.

It was topped off with a few sheets of cardboard weighed down with some wood. I expect it will be heating nicely in a few days and halved in size in a couple of weeks. Then it will need turning.

Composting Gadget


Rockworth 3 Piece Multi-Purpose Drill Attachments Auger

One thing composting does need is oxygen. If the heap doesn’t get any air for the microbes that do the work then it goes over to a different set of microbes – anaerobic (oxygen free) composting which also produces chemicals that aren’t good for soil ecology and growing. Anaerobic is often slimy and smelly but it can be rescued by basically re-composting aerobically (with oxygen).

Even my Hotbin composter can go anaerobic. Usually this happens when it’s needing emptying as the thickness of finished compost in the base slows the airflow to the active upper part or it just compacts due to the waste materials in there. The warning sign is when the temperature fails to reach 60ºC.

They provide a sort of stick for mixing materials and opening the heap up but I saw this auger mentioned on the net as a tool for opening up compost heaps. It was only £7.49 on Ebay including postage so I thought ‘why not?’

It comes with 2 different diameter bits that attach to a shaft that you put into a cordless drill. Seems to be very good value to me. It arrived in the post and I immediately gave it a go as my Hotbin seemed to be choking on the waste from the sweetcorn after we had our freezing session.

Drilled into the heap about five times and a couple of hours later the temperature was up to 70ºC and it was steaming away again. Still needs emptying though!

Posted in Allotment Garden Diary
4 comments on “Composting with Comfrey
  1. lee warhurst says:

    hi just recently read about composting with comfry but my preferd choice would be to not shred the comfry but to try keep it whole not roots just leaf if possibly not seed heads and submerge the whole contents in a water butt to make a super righ food for my allotment and in the greenhouse .. comfry can be invasive if not kept under check but its usefulness far weighs up the downs .. a gardeners must..

  2. John Harrison says:

    Hello Lee
    I wouldn’t bother shredding comfrey as it rots down so quickly. Don’t try to compost the roots or you’ll find it re-growing!
    Bocking 14 is a sterile clone specifically developed for garden use as a ‘fertiliser’ and is not invasive nor can it spread from seed.
    Do check out the pages on comfrey on the site here:

  3. Ken Thomas says:

    Hi John – thanks for the tip re the Rockworth Auger. My hotbin temperature had dropped and I couldn’t get it going again. I saw your comment and bought an Auger from eBay – £5.49 and free postage now! Within 48 hours the temperature has increased from 30C to 53C and is still climbing. I’m extremely pleased. Thanks again.


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