Adverse Effect

Combinations to be avoided at all costs are plants that adversely affect each other. Instead of being seeded in close proximity of each other, they should be as far apart as possible from each other.

Potato:
- Tomato (increases chances of getting phytophthora)
- Sunflower (suppresses growth)

Strawberry:
- Cabbage (promotes rotting of the fruit)
- Potato (promotes fungal diseases)

Beet:
- Runnerbean (attracts the types of insects that will cause damage)

Cauliflower:
- Spinach (suppresses growth)

Beans and Peas:
- Onion (promotes a great number of fungal diseases)
- Garlic (promotes a great number of fungal diseases)
- Shallot (promotes a great number of fungal diseases)
- Leek (promotes a great number of fungal diseases)
- Fennel (suppresses growth)

Garlic:
- Potato (promotes rotting)

Celery:
- Potato (suppresses growth, increases chances for disease)

Cucumber:
- Onion (causes mildew on the cucumber)
- Garlic (causes mildew on the cucumber)

Cabbage:
- Potato (promotes many disease)
- Strawberry (suppresses growth)
- Tomato (suppresses growth, promotes many diseases)

Parsnip/Carrot:
- Tomato (attracts root-fly/carrot-fly)
- Cabbage (suppresses growth)

Leek:
- Cabbage (suppresses growth)
- Beans (suppresses growth)

Radish:
- Tomato (causes flaws during growth, consequentially leaving one with more fragile plants)

Lettuce:
- Parsley (attacks lice)
- Dill (attacks lice)
- Fennel (attacks lice)

Spinach:
- Onion (will suppress it's growth process)
- Garlic (will suppress it's growth process)
- Leek (will suppress it's growth process)
- Tomato (causes rotting of the leaves)

Tomato:
- Swedish turnip (suppresses growth)
- Fennel (causes a many phytophthora)

Onion:
- Bean (suppresses growth)
- Cabbage (lowers production)
- Potato (will promote a lot of fungi)

Offered by Michel.