Just as humans and their activities often prove to be good or bad companions, garden vegetables and fruits exhibit some of the same tendencies. That's according to multiple observers – not necessarily including me.
A classic case of good companions is traced to native Americans. They enjoyed lots of success with the intermingling of corn, beans and squash.
With intensive scale production agriculture for major crops, the recommended practice is to rotate from year to year with three or four crops. Long-term research by the Extension Service strongly backs the benefits of crop rotation.
Friends and enemies
So how does this principle apply to small scale gardening, which typically involves many more plant species? There's a published list identifying good and bad companions for 35 familiar garden vegetables and fruits. I'll focus on the highlights rather than listing all of the details, which can be found online.
Let's start with onions, which don't seem to be the best of neighbors despite their many healthy nutritional traits. They're apparently not good companions when being grown close to beans, peas, and asparagus.
But onions are good neighbors to tomatoes, carrots, strawberries, lettuce, celery and silver beets, which most of us know as Swiss chard. One deficiency on the analysis that I'm referencing is that red beets are not listed.
Potatoes make even more appearances on the bad companion list. They're reputed not to be good neighbors for squash, zucchini, pumpkins, raspberries, sunflowers, turnips and the rosemary herb. But beans, peas, sweet corn, brassicas, marigolds and nasturtiums welcome potatoes as a garden neighbor.
Only onions are listed as a bad companion for beans. Good neighbors for beans are peas, carrots, lettuce, spinach, parsley and cucurbits (squash, pumpkins, zucchini and some gourds).
Tomatoes stir a bit of turmoil in their neighborhood. They're reputed not to be good neighbors for sweet corn, dill, strawberries, brassicas, and potatoes.
But a group of other vegetables love tomatoes as a garden companion. They include asparagus, basil, onions, sweet corn, carrots, cucurbits, celery, parsley, and nasturtiums.
Peppers are not listed on the version that I'm selecting from but I believe they're not good neighbors for either tomatoes or potatoes. That's because, as is the also the case between potatoes and tomatoes, because they are vulnerable to some of the same diseases and pest insects.
For peas, the good neighbors are beans, carrots, corn, potatoes, turnips, cucurbits, celery, and radish. For radish, the group of good companions is almost the same – beans, carrots, peas, lettuce, nasturtiums and cucurbits.
There are even a few crops for which no bad companion is identified. That list includes lettuce, eggplant, chives, celery, spinach, Swiss chard, radish, marigolds and nasturtiums. Carrots have only dill as a bad companion, but dill is also listed as a bad companion for the brassica family.
Garlic is listed as a bad neighbor for beans, brassicas, peas and strawberries. With only apples, peaches and roses identified as its good companions, garlic is apparently lonely in most gardens.