Hi I'm Tricia an organic gardener. I grow organically for a healthy and safe food supply, for a clean and sustainable environment, for an enjoyable and rewarding experience.
Did you know that some plants help each other and some plants hurt each other this is historically been called companion planting but a better term is called plant associations. Plants can't get up and walk away if they don't like their environment so many plants do the next best thing and alter their environment chemically, physically and biologically. When a plant does this their are other species that benefit from the environmental alterations or are discouraged by it. Probably the most famous beneficial plant association is the Three Sisters. Agriculturally inclined Native American tribes often planted corn, beans and squash together. The beans add nitrogen to the soil which the corn feeds off of, the beans used the corn to climb on and the squashes large leaves act like a natural mulch conserving moisture and shading out weeds. Some example of plants that chemically alter their environment are legumes such as lupines, peas, beans, clover and alfalfa they take nitrogen from the air and they put it into the soil. Marigolds are another chemical adjuster they produce thiophene which deters some harmful nematodes. Plants can play off of one another just based on their structure a great example of this is carrots, lettuce and onions because the roots and leaves of these plants grow at different levels they grow very well together instead of competing. Probably the biggest benefit of plant associations is from the biological angle, there are a whole host of plant associations that are based on how they affect the insect world some plants are favorites of nasty bags and if you have problems you may wanna plant a trap crop. I'm going to plant some nasturtiums here next to the kale because the garden baddies will focus on them and they'll leave my kale alone. Many aromatic herbs and Alliums such as chives and garlic will repel pests and make it difficult for them to sniff out their favorite plant and you can leverage this by intercropping.
So instead of planting all the same variety in one place for example all your lettuce here and all your garlic here and all your tomatoes here plant in companion groups. You can also plant to lure the good guys to your garden. Parsley and other umbels are favorites of beneficial insects Not all plants get along don't plant in the same location crops that are susceptible or have trouble with the same diseases or pests For example potatoes and tomatoes are cousins and they're susceptible to the same kind of blight. Other plants either compete or add something to the soil that will stunt the growth of other crops. For example don't plant onions next to your peas and beans or the peas and beans growth will be stunted. For more information on companion planting read this book "Carrots Love Tomatoes; Secrets of Companion Planting for Successful Gardens". Find the best friends in your garden and grow organic for life