Bad companion plants in the vegie garden

Nov 4, 2020 | Gardening tips, Planting guides

What vegetables are bad companions?

Good companion plants are those that benefit each other or one benefits the other. Bad companion plants are those that negatively affect each other or one the other. The effect generally comes through chemicals given off by a plant’s roots. This means spacing is essential – either spacing closely for a positive benefit or at a distance to prevent a negative impact. Generally, at least a square metre is necessary for closeness or distance. It also means planting good companions in sufficient numbers per square metre to gain a positive effect. Here I am going to focus on bad companions.

Asian Greens are affected adversely by parsley
Beans by onion family, sunflowers and brassicas
Beetroot by beans and tomato
Asparagus by onion family and potato
Brassicas* by the nightshade family.** Additionally, cabbages are affected by strawberries and runner beans
Carrots by dill, radish and parsnip
Corn by tomato and celery
Cucumber by tomato and sage
Eggplant by runner beans
Lettuce by celery, cabbage and parsley
Nightshade** family by beans, black walnut, fennel, dill, and brassicas* and additionally peppers by beans and kale, and tomato by corn, peas, potatoes, beetroot, kale and rosemary
Onion family by peas, beans and parsley
Parsnip by carrots, lettuce and onions
Potato by sunflower, carrot, cucumber, pumpkin and tomato
Pumpkins by potato

This seems a draconian list but take into account winter and summer vegetables are not generally grown together and that lessens the impact of the list.

*brassicas are a genus of the mustard family and include cauliflower, cabbage, broccoli, Brussel sprouts, collard greens, Asian greens, kale, kohlrabi, swede, turnip and mustard greens

**nightshade family belong to the Solanaceae family and include tomato, capsicum, eggplant, potato and paprika

Written by Robin Gale-Baker