Companion Planting for Pest Control
One of the advantages of companion planting is the ability to reduce the number of pests you may have to face in your garden without having to spend a lot of time or money on the process. Companion planting can be a big help in this task.
The first step in planning an effective companion planting program is to observe your garden closely to find out what the best candidates are for this "buddy" system. Look for pest damage and determine what pests you are facing. Consider the plants that aren't growing as well and figure out whether they have a pest problem or a nutrient problem. If you're spending a lot of time and money on solving either of these problems, you might benefit from companion planting.
Not all pest problems will be solved by finding plants that are repulsive to them. Pests that like a variety of plants will just move to another part of your garden. In this case, what you need is another type of companion planting. It's a little more subtle than planting garlic next to your roses to deter the aphids. It involves finding plants that will attract the predators of the problem pests.
Companion plants can be repellents, that is, they fend off the pests by producing a taste or odor that the pest finds disgusting. Companion plants can also be nursery sites for beneficial insects and birds that will eat your pests. They can also be decoys and draw the pests away from your "good" plants to a place where you can easily control them.
While it doesn't really come under the heading of "companion"
planting, you can also have your favorite flowers and vegetables with less
pest problems by selection varieties that are less attractive to the pest.
For example, most troublesome birds are attracted to red berries and fruit.
Growing yellow varieties might keep the bird damage down. Aphids are attracted
to yellow, so planting their favorite "food" plants in reds and
blues might keep down the aphid population on the plants.