Comfrey is a dynamic accumulator that mines subsoil minerals and makes them available.
Contested A person has checked it against its sources. The planner leaves it to you.
What is actually known
Symphytum has deep roots and produces large potassium-rich biomass that decomposes fast. That is a good mulch plant. The specific mineral-mining claim has very little behind it.
When this applies to a garden, Milpa says: Comfrey makes excellent chop-and-drop mulch. The mineral-mining story is unsupported.
The evidence
Evidence: checked against 1 source in the research-based literature.
The source
… has shown Russian comfrey to be a dynamic accumulator of both potassium and silicon
Plants it applies to · 1
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How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Sources updated
- A person read the sources and confirmed it
- Added to the rules
When do I plant Russian comfrey? ›
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Cite this page
Milpa Gardens. “Comfrey is a dynamic accumulator that mines subsoil minerals and makes them available.” Evidence grade: Contested. https://milpa.garden/rules/comfrey-dynamic-accumulator-that-mines-subsoil-minerals/
A garden planner built on graded evidence. Every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.
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How we grade evidence
- Well established
- The rule names its mechanism and is settled, by sources a person has read and checked or by plain arithmetic and geometry.
- Promising
- The mechanism is named and the literature backs it. A few questions are still open.
- A good hunch
- Plausible by its mechanism, but field studies are thin, so treat it as a lean.
- Contested
- The evidence points both ways, or no study has tested it, so the planner does not enforce it.
- Refuted
- The claim did not survive its sources. It is kept so the folklore can be answered.