Bad Companions or enemies usually means that they would compete for the same nutrients causing smaller plants and less produce. It can also mean a change in flavor.

Here is what my list has as far as good and bad companions for the veggies you want to plant.

Tomato friends: carrots, celery, cucumber, marigold, nasturtium, onion, parsley, pepper.

Tomato enemies: Cabbage, kohlrabi, potato.

Lettuce friends: Beets, cabbage, carrot, cucumber, kohlrabi, onion family, radish, strawberry.

Radish friends: Carrot, cucumber, leaf lettuce, mustard, nasturtium, parsnips, pea, pole bean.

Spinach friends: Cabbage, strawberry.

Pepper friends: Carrots, eggplant, okra, onion, parsnip, tomato.

Hope this helps

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Swede is rutabaga.

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What about vegetables that aren't listed as good or bad?
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These are OK to interplant. They just don't affect one another in any discernible way.
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http://en.wikipedia.org/wiki/Rutabaga
More on the swede (yellow turnip.) Yummo.

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The secret is the soil.