Plant compatibility is a huge area for research. Moreover, these studies can be carried out by agronomists, botanists, and ordinary gardeners.
Experiments can be conducted directly on the garden bed, planting different crops together and observing their development. Moreover, the results may differ depending on the site, because the soil, the angle of incidence of sunlight, and the degree of shading also play a role in this experiment.
Everyone knows about the banal combinations - onions and carrots, garlic and strawberries, tomatoes and basil. But there are more interesting combinations.
Note: The science that studies the effect of some plants on others is called allelopathy.
Many people think that cucumbers climb corn, so they are planted together. But this is not true. The corn trunk is too thick for the cucumber tendril.
But these plants grow well together, and the yield of cucumbers increases. It is not known exactly how corn works, but cucumbers clearly like it. The situation is similar if you plant pumpkin, squash, pattypan squash and other pumpkins with corn.
In hot weather, corn shades the bed, but the shade is not dense, which suits the cucumber. Corn also absorbs a lot of water, but its roots go deep. When there is excess moisture, it absorbs the excess so that the cucumber does not rot. And during drought, it takes water from the deep layers of the soil, not competing for moisture with the cucumber.
This combination has proven itself excellent both for currants and tomatoes. Both crops grow well next to each other and bear fruit abundantly. And the smell of tomato disorients currant pests.
This combination was used by our grandparents. Now beans and kidney beans are not popular with summer residents, but they used to be planted without fail. And often they threw a kidney bean or a kidney bean right next to the potato when planting. Legumes enrich the soil with nitrogen and repel many potato pests, such as wireworms and nematodes.
The cruciferous flea beetle does not like lettuce, so it can be sown between rows of cabbage, radish, horseradish and other cruciferous plants.
Cucumbers, pumpkins and squash like to grow next to raspberries. It may be because of the shade, but it is not known for sure.
It is worth remembering that there are also unfavorable combinations. For example, corn grows worse next to raspberries, beets suppress peppers, rye suppresses all other plants, as does red clover.
You shouldn't plant cucumbers next to eggplants, as eggplants are a breeding ground for spider mites. And eggplants themselves should be kept away from potatoes, as all the Colorado beetles will crawl onto them.