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Vegetable Companion Planting: Key Unfavorable Associations to Avoid

A Practical Guide to Unfavorable Vegetable Plant Pairings

As experienced gardeners know, not all plants make good neighbors. While some conflicts have clear explanations—such as Alliaceae (garlic, onions, shallots) releasing root bactericides that harm Fabaceae legumes (peas, beans, broad beans) by disrupting their azotobacter bacteria—others stem from observed field results. Planting same-family crops together also amplifies pest risks, like the Colorado potato beetle attacking both potatoes and eggplants.

Practical observation trumps theory here. Where no associations are listed, reliable sources yielded no data for that crop.

Vegetables | Unfavorable Associations

VegetableUnfavorable Associations
GarlicAsparagus, beans, peas, cabbage
AsparagusGarlic, onion
EggplantPotato
BeetrootBean, leek, carrot, tomato
CarrotBeet
CeleryCorn, lettuce
ChicoryCabbage
CabbageChicory, fennel, strawberry, leek, grapes, garlic
CucumberPotato, tomato, radish
SquashRadish
ShallotBeans, peas, cabbage
Spinach
FennelCabbage, beans, parsnips, tomato
Fava bean
StrawberryCabbage
BeanGarlic, shallot, fennel, onion, leek, peas, tomato
LettuceParsley
Mash
CornBeetroot, celery, potato
Melon
Turnip
OnionBeans, peas, asparagus, cabbage, potatoes
ParsnipsFennel
ParsleyPeas, lettuce, leek
Dandelion
LeekCabbage, beets, beans, parsley
PeasGarlic, shallot, bean, onion, parsley, potato, tomato
PotatoGarlic, eggplant, beetroot, cucumber, corn, onion, peas
RadishCabbage, squash, pumpkin
Salsify
TomatoBeet, cucumber, fennel, bean, pea

Vegetable Companion Planting: Key Unfavorable Associations to Avoid