The tips and secrets listed in "Carrots Love Tomatoes" and "Roses Love Garlic" are a bit mind-bending to watch in action. Some plants, like tomatoes and basil, really do thrive when they're growing in close proximity to their "friends." Others, like mint, really do deter cabbage moths.
(Mint can also root through the drainage holes of specially sited pots -- so be careful when placing it among your broccoli, et. al. We've learned the hard way.)
Each year, we've made a point of adding a few more helpers into the mix. My favorites are perennials because I can rely on them to do their jobs so I can focus on other things. Those that reseed themselves are nearly on a par --as long as they don't migrate to undesirable places.
Each year, we discover sunflower volunteers popping up every-which-where and it breaks our hearts to yank babies in in opportune sites.
Next in the hierarchy are the tried-and-true annuals that find their way into my routines. Marigolds and basils are chief among these.
This year, we're giving four o'clocks a second try -- I had poor luck germinating them last year -- and adding zinnias. Both are said to serve as trap crops for Japanese beetles.
I will certainly become a lifetime member of both their fan clubs if this plays out.