The Facts That Support Companion Planting
Some gardeners consider companion plants little more than a myth or folklore. But as with many fables, this one has a basis in reality. Plant biologists are only now uncovering some of the ecological and biochemical facts behind this practice.
People have practiced companion planting for many thousands of years. Through observation and experimentation, they discovered that certain plants grow better when in close proximity to others. They may provide or share essential nutrients, or one plant may shade another. Some wildflowers and even weeds make great companion plants. They may repel insects or attract helpful ones.
Evidence of companion planting by Native Americans in both northern and southern hemispheres shows that it has been practiced for over six thousand years. By examining the seeds and rind of preserved crop plants, scientists found that Indian cultures deliberately selected and seeded plants with certain characteristics. These ancient farmers developed a complex system of growing vegetables involving cooperation between three staple crops, known as the Three Sisters. Corn is planted in little hills, with beans and squash surrounding it. As the corn grows tall, the bean and squash vines can climb on it. The beans add nitrogen to the soil, while the broad leaves of the squash create shade, stop harmful weeds and pests, and provide additional nutrients.
Examples of Companion Choices
There are many methods for growing vegetables together with other vegetables, herbs or flowers. Each pairing has its own kind of etiquette in terms of when, how and where they should be planted. Usually the companions should be planted at least a foot away from each other, so they have plenty of room for roots to spread. The best known combinations include roses with onions, carrots with peas, and basil with tomatoes. Sunflowers provide shade and make good support for cucumber vines. Marigolds and yarrow can be planted next to almost anything for their pest- repelling magic.
Most plants have garden "enemies" as well as companions. Beans and garlic should not be planted near each other, as the garlic will inhibit the growth of the beans. Plants that consume a lot of fertilizer will compete for nutrients and should not be placed near each other. Certain herbs are beneficial to nearby plants but harmful to animals. Be very careful about tansy, sorghum and pennyroyal. Some crops can be planted in the same area year after year, while most will need to be moved around to give the soil a chance to replenish itself.
Brief Summary of the Benefits Of Companion Planting
- Helping each others growth- so for example, plant prostrate horizontal growing vegetables like cucumbers under taller growing veggies like tomatoes bushes for the shade benefits to the smaller plant
- Better use of space in the garden- in the example above, the cucumber is a vine plant that could grow around the base of the upright tomato plant (be sure to prune off lower stems of the tomatoes trunk and support it with a "'tomato cage").
- Pest Control- Veggies like onions repel many garden pests while other plants actually lure pests away from your favoured vegetables.
- Attracting Beneficial Insects-Many companion combinations attract beneficial insects such as lady bugs and other predatory insects that control the harmful plant eaters
If you plan on growing vegetables and herbs in your own garden, a companion planting guide is a valuable reference tool. You can find them free online or buy them from your favorite seed supplier. Consult your local cooperative extension for detailed information.
For a comprehensive listing of Companion Planting choices click here