It has been found that certain plants do not grow their absolute best when they are neighbors with certain others. There are plants that help each other grow well, help repel insects, and even plants that hinder the development of other plants. Reasons for this are varied and research is helping to solve the mysteries of the magnificent and complex plant world. Scientific studies and gardener’s experimentation has shown several benefits from companion planting:
- Masking or hiding a crop from pests.
- Producing an odor that confuses and deters pests.
- Serving as a trap crop that draws pests away from other plants.
- Providing food for beneficial insects.
- Creating a habitat for beneficial insects.
For instance, marigolds and nasturtiums seem to act as a repellant to insects like aphids. This actually happens through secretions in the root system rather then flower fragrance. They are more useful the larger the root system is (more mature plants). Marigolds planted next to lettuce, leave secretions in the soil so that next years lettuce will reap the benefit.
You will reap many benefits by garden diversifying. If you plant one crop at a time, you are more likely to attract only a small variety of pests or diseases, however they usually will be in great number and can destroy your entire crop. If you plant two or more crops together, you may have a variety of pests but they will usually be fewer in number. Diversifying allows for a more stable environment for the various pests to keep each other in check.
Companion planting can attract beneficial insects as well. We don’t have praying mantis, nematodes, or beneficial wasps naturally in the Interior, however you can order them from the Internet. Ladybugs are very helpful and they can be purchased in egg form and they are naturally occurring here in small numbers. Most “beneficials” are not loyal and will leave when the food supply (pests) is gone. You can cultivate plants to lure beneficial insects to your garden. Here is a list of plants that will do that:
- Achillea spp. (yarrow) and Veronica: bees
- Angelica archangelica(Angelica): Ladybugs
- Ipomea purpurea (Morning Glory): Ladybugs
Your aim is balance. Balance in sunlight, water, diversity, soil conditions, and space. You can interplant crops for efficient use of space. For instance, plant basil below and outside the leaves of your tomatoes. They grow well together and it’s easy to pick for a salad or tomato sauce. You will have to clip the lower leaves so sunlight reaches the basil.