Do not plant lettuce or its family in ground that held it within 3 years, and know that lettuce drop's fungi live on most other vegetables too.
A good hunch · costly if ignored → advise
How it works
Bottom rot (Rhizoctonia solani) and lettuce drop (Sclerotinia sclerotiorum and S. minor) survive in soil as mycelium and sclerotia for years and build where lettuce repeats; a three-year break holds bottom rot down. Drop's fungi infect alliums, brassicas, nightshades, cucurbits and legumes as well, so a lettuce rotation slows them without starving them, and only cereals are safe ground.
What to do about it
Plant lettuce and its family in different ground, or wait until 3 years have passed since this ground last held them. Where drop has shown, the break that counts is one of grains or corn, since most vegetables carry it, and dead plants go in the bin, not the compost: the sclerotia survive it.
How much it matters: Cornell's rotation table: lettuce bottom rot 3 years, drop 3 years. NC State: the broad host range 'significantly limits the efficacy of crop rotation'; cereals are less susceptible. USU: rotate with non-susceptible crops such as grains or corn. UMass: sclerotia survive in the soil for many years.
The evidence
Evidence: confirmed against 4 sources in the research-based literature.
the 4 sources
Cornell Vegetables, 'Do Rotations Matter within Disease Management Programs?', vegetables.cornell.edu/pest-management/disease-factsheets/do-rotations-matter-within-disease-management-programs (fetched in-container 2026-09-02; read by the maintainer 2026-09-02): its rotation table gives lettuce bottom rot (Rhizoctonia) 3 years and drop (Sclerotinia) 3 years.
NC State Extension, 'Lettuce Drop', content.ces.ncsu.edu/lettuce-drop (fetched in-container 2026-09-02; read by the maintainer 2026-09-02): 'Sclerotinia sclerotiorum and S. minor have a wide host range infecting allium (onion, garlic), brassica (cabbage, broccoli), solanaceae (pepper, potato), cucurbits (cucumber, squash), lettuce, and sweetpotato crops'; 'Cereals (maize, wheat, sorghum) are less susceptible to these pathogens'; 'the broad host range of both pathogens significantly limits the efficacy of crop rotation.'
Utah State University Extension, 'Drop (Sclerotinia Rot)', extension.usu.edu/planthealth/ipm/notes_ag/veg-drop-sclerotinia (fetched in-container 2026-09-02; read by the maintainer 2026-09-02): 'The sclerotia can survive dormant in the soil for extended periods'; 'S. sclerotiorum affects a wide range of hosts, including root crops, legumes, and solanaceous crops however, drop is specific to lettuce'; rotate 'with nonsusceptible crops such as grains or corn to reduce disease build-up.'
UMass Vegetable Notes 2024 vol. 36:2, umass.edu/agriculture-food-environment/vegetable/newsletters/vegetable-notes/vegetable-notes-2024-vol-362 (fetched in-container 2026-09-02; read by the maintainer 2026-09-02): bottom rot - 'Rhizoctonia survives in the soil, as mycelium or sclerotia'; lettuce drop - 'It produces sclerotia that can survive in the soil for many years'; 'Its host range includes many vegetables such as tomato and beans.'
Plants this fires on
- Artichoke
- Calendula
- Chamomile
- Cosmos
- Endive
- French Marigold
- French Tarragon
- Lettuce
- Purple Coneflower
- Sunflower
- Yarrow
- Zinnia
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.
- rules: another rule here - lettuce and its family rotate on a 3-year interval (verified, A good hunch) (O133 step 7, family 5 - the step closes)
Cite this page
Milpa Gardens. "Do not plant lettuce or its family in ground that held it within 3 years, and know that lettuce drop's fungi live on most other vegetables too." Evidence grade: A good hunch. https://milpa.garden/rules/do-not-plant-lettuce-family-ground-that/
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.