Consider companion planting to help improve your garden's growth. Companion planting lessens or eliminates the need for chemical pesticides. When you plant certain vegetables side by side, you'll see the results as your garden deters pest insects and attracts beneficial insects. In addition to using other vegetables, planting certain herbs and flowers can help your garden thrive. Use the proper companion planting layout to ensure success.
As defined by North Dakota's Cass County Extension, companion vegetables mutually benefit one another when planted side by side. For various reasons, the mutually beneficial relationship shared by these plants helps them to grow better than unaccompanied plants. Consider the "three sisters" technique implemented by the Native Americans. When planted together, corn, beans and squash aid each other's growth. Corn provides supports for bean stalks, squash covers the ground to block out harmful weeds and beans produce their own nitrogen so there's less competition for nutrients.
Other examples of common companion pairings include carrots with tomatoes, peas with cucumbers, strawberries with lettuce and parsley with asparagus, just to name a few.
While companions are vegetables sharing a mutually beneficial relationship, allies are herbs and flowers that protect your vegetables from pest insects. In addition to repelling certain insects, these ally herbs and flowers can improve your vegetables' flavor, aid growth and attract beneficial insects. For example, marigolds serve as good allies to just about any vegetable because they deter harmful beetles. If you grow peas, lettuce or celery, chives and garlic will keep aphids away from your crop.
In general, planting flowers near your vegetable garden will attract beneficial insects that need pollen or nectar. For this reason, you'll often see roses planted alongside grapevines at wineries to attract ladybugs, spiders, parasitic wasps and other beneficial insects.
It's not always beneficial to plant vegetables together. Be wary of enemy plants, or vegetables that will impede one another's growth. When two species of vegetable have to compete for space, sunlight or nutrients, you'll wind up with a poor crop. For example, garlic and shallots will stunt the growth of beans. If you plant pole beans and beets together, they'll both suffer from stunted growth.
Certain pairings don't necessarily compete for space or nutrients, but they create a mutually harmful environment. If you plant corn and tomatoes together, for example, you'll create the ideal environment for a pest species of worm that likes to eat both plants.