Biochar Vs. Ashing: What’s the Difference?

As we increase production on our farm, we’re looking to the biodynamic practice of ashing to keep Canada thistle under control.

by Dawn Combs

You’ve likely heard of biochar and its use in the garden. We’re often asked if this is the same as the biodynamic practice of ashing, or peppering. Surprisingly, the two practices seem similar but are done for different reasons. Biochar, charcoal used as a soil amendment, is intended to improve soil condition by adding humus, increasing soil organism relationships and sequestering carbon, while ashing is aimed exclusively at eliminating insect pests, animals or weeds from a field or garden.

Ashing or peppering isn’t typical of the biodynamic approach because it doesn’t focus on achieving soil health and balance to eliminate a problem. Usually biodynamic farmers allow weeds to run their course because, with patience, they will eventually heal the soil by fixing nutrients either through their roots or as a compost. Occasionally, though, there’s no time for patience. When your yields are being driven down by something like Canada thistle (Cirsium arvense) and you need to get your produce to market, an emergency solution may be needed.

Biochar Vs. Ashing: What’s the Difference? - Photo courtesy Anita Gould/Flickr (
Courtesy Anita Gould/Flickr

To create the pepper, collect the seeds of the weed in question and burn it down to ash at the full moon. If seeds aren’t available, you can collect the roots. Sprinkle the resulting ash onto the problem area as is, or add it to sand to spread more easily. It doesn’t take a whole lot of the ash, and you don’t need to be too worried about covering a certain amount of soil. It’s similar to a homeopathic application in the human body: Like treats like, in very small concentrations.

In some ways, having Canada thistle around hasn’t been all bad. For years, I stared at the sheer numbers of them and thought I’d be a millionaire if only I could find a way to make them useful. This led me to spend quite a bit of time in research, and one day, a chance conversation with an old college professor gave me the answer I was searching for. Most members of the thistle family benefit the liver, and I suspect there’s something for this organ in the Canada thistle, as well. However, what I have learned is that this weed, when made into a tea, is an effective diuretic. I have added Canada thistle to my ever growing apothecary and am keeping notes on its effects.

Biochar Vs. Ashing: What’s the Difference? - Photo courtesy Anita Gould/Flickr (
Courtesy Anita Gould/Flickr

On our farm we have watched the Canada thistle work its way through at least one of our heavy production gardens. For a few years it grew very thick, but the soil has improved with its help of, and they are now few and far between. It was frustrating to allow this process, but we had other gardens working, so we were able to wait. These days, as we break new ground and need to get higher production, the practice of peppering is now something we are looking at to shorten our suffering and increase our production.

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