Knowing what plants to grow next to each other in your garden, also known as "companion planting," is an important key in building a sustainable organic garden. Even if you do not choose to garden in a wholly organic way, your plants will still benefit. By planting things together that benefit each other, you are creating a miniature ecosystem in your garden. Instead of having a series of individual plants that live or die by themselves, you are building a strong and interwoven gardening mesh.
Plant marigolds next to just about anything, particularly in vegetable gardens. Marigolds exude a strong odor that many pests do not like. The good news is that, although you will notice its smell, most humans do not find it offensive. Marigolds are an all-purpose natural deterrent of animals, birds and insects.
Place pots of plants in the mint family (including catnip) around your garden. Some species of mint can be invasive, so you may not want to plant the mint in the ground with your other plants. However, the strong smell of mint-family plants is another natural pest deterrent. If you plant catnip, be aware that your garden will suddenly become popular to the neighborhood feline population. All those cats will keep birds and rabbits in check, if they are a problem.
Plant tarragon and basil with your vegetables. Tarragon is a perennial, which can be a bonus because it is one less thing to worry about planting next year, unlike basil. Both herbs go well with a variety of vegetables, in addition to deterring many garden pests. Having a steady supply interspersed throughout your garden makes it that much easier to pick some when you harvest your vegetables.
Plant chives around the bases of young fruit trees. Chives are another perennial, and one that is almost impossible to kill. They will die back into the ground after the first frost, but will come back again in the spring. Young fruit trees are susceptible to many diseases and insect damage. Chives can play a vital role in staving off these growing pains.
Plant rue around your entire garden. Be careful, though; rue can be irritating for some people, causing an itchy rash on contact. Rue keeps Japanese beetles away from anything it's planted near.
Learn which plants not to plant together, because that list is much shorter and easier to remember. Squash, tomatoes, turnips and cucumbers should never be planted near potatoes. Onions do not mix with peas and beans of all types. These plants feed heavily on the same nutrients in your soil and will steadily deplete both your soil and each other if planted together.