The plant families list below focuses on the vegetables whose fruits we eat (tomatoes, cucumbers), but not actual fruits (raspberries, peaches). I also include some common landscape plants for the home gardener’s reference, and tips I know from companion planting and permaculture.
We know from the Iroquois legend of the Three Sisters that beans, corn, and squash all get along. They’re all mild, easy-going, pleasant flavors, nothing acidic or spicy or sour, so to me them getting along makes sense.
Cucurbits tend to be big plants with big leaves, and the vine-ing varieties can ramble for a fair distance. In addition to pinching the ends off to stunt the growth a bit, consider sending some up trellises or arbors (but support any heavy fruits). Little kids really love an array of colorful gourds hanging down over head.
Legumes: beans and peas, etc. This family is discussed more thoroughly on the Soil Rebuilding Families page, though yes, both peas and beans are the fruits (seeds) of the plants.
Nightshades: Tomatoes, potatoes (see also Soil Rebuilding Families), eggplants, peppers, tobacco (including the flower Nicotania), tomatillo. Petunias are botanically part of this crew, too, but lack the swashbucklin’ bravado of their kin. Petunias are much more get-along, go-along in the garden.
The rest of the spicy, acidic nightshade family, however, has many enemies in many kingdoms and phyllums: fungi, molds, viruses, bacteria, insects, mammals, birds…. This means there are cross-contamination issues; certainly smokers need to wash their hands before handling any members of this family.
The nightshades don’t like beans. I think it’s because the beans make the soil too rich, which makes them too tasty to their enemies. I finally started raising eggplants instead of flea beetles the year I put them in a new bed with poor soils.
The nightshades also don’t like cabbages. Apparently, although they are good with lower nitrogen soils, they don’t like to actually bed down with the hungry little garden hippos that eat that nitrogen. Picky picky!
Garden Hints for Fruiting Vegetables
The really key thing here is that every last one of these plants doesn’t do what we really want it to do (produce tasty fruit) until after it has flowered. This makes them very hard to include in plans for season extension (although pea greens can be tasty.)
Also, each of these families includes a fair number of options for trellises and other fun vertical whimsies. Play!