Every day I see signs of chemical and biological warfare. I also witness compatibility, prosperity and growth. This isn’t happening in some far-off land. This is in my garden!
Companion planting combines two or more different species for cultural benefits. Each plant brings a desired trait that is lacking in the group. Much of the success of companion planting can be attributed to folklore. But there is some science behind companion planting.
Some plants contain natural insecticides like pyrethrum found in the chrysanthemum family. Legumes have the capacity to pull nitrogen from the air and convert it to nitrogen in the soil. Highly scented plants like sweet alyssum attract beneficial insects. Some plants taste bad which discourages insect and animal nibblers.
One of the best-known examples of this principle is “The Three Sisters”. Native American tribes cultivated corn, beans and squash together in mounds.
The corn provided support for the beans. The beans (which are legumes) feed the corn which is a high nitrogen consumer. These vegetables are a perfect pair. The squash served as a groundcover which kept the roots cool and crowded out weed competition.
Beneficial insects can be classified as predators or pollinators. Predator wasps, ladybugs, lacewings and others are attracted by scent. Highly fragrant flowers also attract bees and other pollinating insects. As a bonus, hard to pollinate flower species get a boost from the visiting insects.
Marigolds, for example, contain a chemical in their roots that kills harmful nematodes. The scent of Marigolds as with most herbs also repels many harmful bugs. Chives have an anti-fungal property that when planted beneath roses can help deter blackspot. Daffodils are an example of plants that taste horrible to most animals. Planting daffodils around other spring bulbs can help protect them from squirrels and other burrowing animals.
An example from personal experience is how basil enhances tomatoes. It is believed that when tomatoes and basil share close proximity in the garden that the flavonoid (chemical part of a plant that produces flavor) in tomatoes better develops. There is some dispute to this relationship, but I’ve always had more flavorful tomatoes and a better yield with these plants side-by-side.
It is important to remember that not all plants are compatible with each other in the garden. Take the time to do a little research about individual plant needs and characteristics. Remember that every plant in your garden is competing for available water and nutrients.
Some plants emit chemicals that discourage or kill other plants. This property is called “allelopathy.” Walnut trees for example, contain an herbicide that makes it difficult to grow many plants near their root system.
Companion planting instills a return to environmentally friendly gardening practices. By using natural plant survival mechanisms, we can learn to incorporate a wealth of knowledge from the botanical world into everyday gardening.