artemesia's kind of like rue that way-

I'd plant it as a barrier (I'm working on getting enough cuttings of the silver mound from my MIL's to edge one of my beds) but not interplanted (which you can do freely with garlic, and marigolds to the same effect)

I don't have any of my books with me, but I'd guess twice the diameter of the plant away.

Thanks for the info. I'm not sure what you meant by the first line though, "artemesia's kind of like rue that way". I think the twice the diameter of the plant rule gives me plenty of room. I was going to put in the marigolds, but didn't know about the garlic, thanks. If I can only remember to plant some bulbs in the fall. Does anything else go well with Tomatoes?

Rue's a plant that no other plant seems to like being near...it's also astringent in nature, I've not met a bug or critter yet that will nibble at it, either. so it makes a good 'barrier' plant, but a bad companion.

Basil, garlic and marigolds are the classics- they all seem to work well together.

Pineapple sage seems to like tomatoes as well.