Alliums and carrot family are unrelated to nightshades/cucurbits/brassicas and can break those families' rotation cycles — but they are not "low-pressure" and need their own rotation.
A good hunch · suboptimal if ignored → advise
How it works
They host none of the big-three families' soilborne pathogens, so following those crops with an allium or apiaceous crop breaks the host cycle. But they are not inherently low-pressure: allium white rot (Sclerotium cepivorum) is allium-specific, its sclerotia persist 15+ years, and it cannot be eradicated once established; apiaceous crops carry their own soilborne diseases.
The evidence
Evidence: confirmed against 1 source in the research-based literature.
the source
UMass Extension, 'Alliums, White Rot', ag.umass.edu/vegetable/fact-sheets/alliums-white-rot (read 2026-07-11): 'Sclerotium cepivorum is specific to allium species'; sclerotia 'may remain viable in soil for 15 years or more without allium hosts'; 'Currently, there is no way to eradicate white rot from a field where it has become established.'
Plants this fires on
- Carrot
- Celery
- Chives
- Cilantro
- Daffodil
- Dill
- Fennel
- Garlic
- Leek
- Lovage
- Onion
- Parsley
- Parsnip
- Scallion
Change history
Every change to this rule is one commit. This is what the project's version history records — the date and the reason — not a summary of it.
- engine: the rotation maps are read from the corpus; another rule here states the cycles it breaks (O133 step 7 prep)
- promote to verified — allium/apiaceae break needs its own rotation
- cite UMass white rot; alliums are not "low-pressure"
Cite this page
Milpa Gardens. "Alliums and carrot family are unrelated to nightshades/cucurbits/brassicas and can break those families' rotation cycles — but they are not "low-pressure" and need their own rotation." Evidence grade: A good hunch. https://milpa.garden/rules/alliums-carrot-family-unrelated-nightshades-cucurbits-brassicas/
A garden-planning corpus: 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.