Companion Planting is, as its name suggests, the technique of growing various flowers and vegetables next to each other for their mutual benefit. When done correctly this can both increase yields and also deter pests from attacking the crops. I have to admit that apart from the simple example of growing marigolds next to vegetables to repel insects, I find that trying to make a plan that combines the perfect companions with the needs of crop rotation to be beyond me. But for a more balanced view read this article by Master Gardener Phyllis Heuerman which I found over on The Master Gardeners website.
Companion planting can be described as growing two or more different kinds of plants close together so that some benefit is derived, like repelling pests, attracting beneficial insects, adding needed nutrients to the soil, or providing shelter.
Companion planting is not new. For centuries many Native American tribes throughout North America have cultivated corn, beans and squash together. The Iroquois called them the “Three Sisters.” Although the tribes did not know the scientific basis for it, they knew these crops thrived together. Corn provides a structure for the beans to climb. The beans replenish the soil with usable nitrogen and other nutrients, and the large leaves of the squash provide a living mulch that help conserve water and provide weed control.
If you have seen vineyards in the western United States you will often see rose hedges along the vineyards. Although they are beautiful, they are not just for show. Roses are susceptible to many of the same diseases as grapes, but the show symptoms sooner. If the vintners see signs of disease on the roses, they can take action to treat the grapes before symptoms occur on them.
Another kind of companion planting is called trap cropping. As an example, cucumber beetles, which transmit bacterial wilt, prefer squash and pumpkin pants over cucumber and melons. If you want to protect the latter and are willing to sacrifice the former, plant them close by.
By using companion planting, many gardeners find that they can discourage harmful pests without losing the beneficial allies. It can combine beauty and purpose to create a beautiful garden. There are many varieties of herbs and flowers that can be uses for companion plants. Experiment and see what works for you.
See more at The Master Gardeners