Somehow conventional agriculture decided that planting rows and rows of the same crop stretched out for what seems like miles was the best solution for growing food. Unfortunately, they are dead wrong. Have you ever seen row after row of the same plant in nature? No forest will show you the same species of trees aligned in a pristine matrix. A grassland ecosystem has different species of grasses and shrubs interspersed everywhere. It seems as if there is no logical order. And yet, out of this chaos arises a stable ecosystem at equilibrium. It needs no human intervention to continue thriving.
The permaculture idea of companion planting comes from this chaotic diversity of plants. In truth, it’s not a chaotic system. There are very good reasons nature chooses to grow different species together. The main idea is based on the fact that different plants serve different purposes. Having different species next to each other can provide complementary benefits. Some plants have long taproots that bring up minerals locked deep in the soil subsurface, where most other plants can’t reach them. Flowering plants attract pollinators, which helps non-flowering plants to reproduce and bear fruit. Some plants need more nitrogen than others, and are happiest next to a plant that releases nitrogen into the soil. Knowledge of these intricate relationships were lost in the transition to chemical agriculture, but they are not experiencing a revival as more and more people choose to garden and farm organically. Choosing to grow food in a monoculture system (where there’s only one crop species planted row after row) drastically reduces diversity in all realms, thereby reducing pest and disease resistance, and the crop’s overall vitality.
Companion planting is a central component of permaculture. Plant diversity increases soil and insect diversity, which limits the number of pests that can cause disease and crop loss. Companion planting increases yields and reduces time spent weeding and managing pests and disease.
Dandelion has traditionally been seen as a scourge that should be annihilated. And yet, permaculturists often plant dandelion because its long taproot has the ability to bring calcium locked in the deeper soil horizons up to the surface. In this way it makes calcium available to plants that need it. Not only does it provide calcium, it also releases ethylene, which is a plant hormone that encourages fruit setting and ripening. As it is a flowering plant, it attracts pollinators that help your crops to bear fruit.
Every plant has a variety of functions and services, and there are now plenty of companion planting charts and books to help you decide which varieties would best serve your garden.