Organic Gardening: Companion Planting

In the estimated 10 000 years modern man has been cultivating, through a practical empirical understanding, relationships between plants were recognised, utilised and extended in our cultivation techniques. This relationship knowledge has come to be known Companion Planting. One of the oldest known companion planting techniques comes from the Native Americans and is called the Three Sisters. This technique comprises three staple foods maize (corn), beans and pumpkin that are planted together in a companion plant group.

The Maize is first planted three to four seeds close together on top a mound of earth. When the maize reaches average knee height the beans and pumpkin are planted around the maize. The beans grow up the maize which is now their climbing pole, as nitrogen fixers they act as a living organic fertiliser for the maize and pumpkin. The pumpkin spreads out from the mound along the ground and retards the growth of other competitive plants in the group’s vicinity.

Together they actively help one another to achieve a greater potential than if they were planted alone, and this is what companion planting is all about, knowing, seeing, understanding and utilising the natural relationships between plants.

With the Three sisters technique we can see the functions that aide each plant and the cultivator.

The Bean = Food, fertiliser, pest repellent.

The Maize =Food, climbing pole, pest predator attractant.

The Pumpkin = Food, ground cover, weed repellent.

This is only the beginning there are many more relationships that once learned can be included into a larger system. On the flipside there are also plants which don’t do well together i.e. Walnuts from the Genus Juglans are allelopathic that is they have a chemical compound content that engenders in Solanaceae Family (Tomatoes, Potatoes, Tobacco etc. see this article link for more about The Solanaceae’s), a negative reaction to those compounds.

How the Juglans Genus does this is to exude the chemical Juglone through their roots. The Juglone compound inhibits metabolic enzyme reaction in other plants but in particular greatly effects the Solanaceae Family and retards their growth rate. Though Juglone is present in all the Juglans Genus is it of particular high concentration in the Black Walnut (Juglans nigra). The actual scientific field of allelopathy is a relatively new discipline, but certainly most needed, this one aspect of companion planting holds a key to further understanding what is happening between plants and their environments as a whole system at the chemical compound level.

Though in general companion planting is based on folklore and anecdotal evidence it in fact amounts to thousands of years of traditional farming practises passed down by word of mouth. These practises are remembered because they have stood the test of time, though we are now able to begin scientifically, a validation process for many of these empirical age old observations. To get you started in this dynamic practise of companion planting here is a list of some plants and their functions that can be utilised within a companion plant grouping.

Lettuce grows well with kohlrabi, beans, carrots, radishes, strawberries and mints but not with beans, beetroot, parsley, celery, cabbage and cress. In the case of lettuce the mints help repel slugs and other soft bodied pests.

Tomatoes grow well with basil, oregano, parsley, carrots, marigold, celery, geraniums, petunias, roses, peppers and asparagus, but not with black walnut, maize, fennel, peas, dill, potatoes, beetroot, kohlrabi, cabbage, rosemary and nasturtiums. Tomatoe is known to repel the asparagus beetle, and its leaves are highly toxic.

Peppers from the Capsicum Genus grow well with other capsicums, tomatoes, geraniums, petunias, and marjoram, but not with beans, kale, cabbage and brussel sprouts. The peppers themselves are an irritant to most soft bodied pests.

Onions grow well with broccoli, cabbage, lettuce, strawberry, tomatoe and carrots, but not with beans, peas, parsley and leeks. Onions repel aphids, rose chafer beetle and carrot flies, weevils, moles, fruit tree borers it controls rust flies and some nematodes and especially protects tomatoes against red spiders.

The herb Borage grows well with strawberry, cucumber, gourds, and tomatoes amongst many others. Borage repels tomato worms and attracts honeybees.

Peas grow well with Beans, Carrot, corn, cucumber and radish but not with most Alliums (Onions, garlic etc). Peas are Leguminous and like beans give nitrogen to the soil.

Marigolds have long been hailed and for good reason, it grows well with tomatoe, potato, strawberry, melons, cucumbers, gourds, apple trees, broccoli, cabbage, radish beans and roses. Marigolds encourages growth an repel Mexican bean beetles and other pests, but significantly harmful nematodes.

Mustard grows well with cabbage, cauliflower, radish, turnips, collards and kohlrabi, it can also serve as a trap plant that attracts harmful insects to itself over other plants.

As you can see just from these eight plants, once you know their companions, enemies and what they do in terms of pest control you can begin to form groups of plants that do especially well together. The more information you gather on companion planting the more you can do in your garden design; the possibilities of various groupings for various effects can become virtually limitless.

Companion Planting combined with all the other aspects of organic gardening give you the ability to emulate a natural system, but a system that works for you as a gardener. The general rule I go by is that each and every plant must have at least three uses and work in combination with each other. The Three Sisters grouping is a perfect example of this each one has three uses and they work to the benefit of each other and ultimately you as a gardener. For a full listing of companion plants try a Google search on companion plants . Once you begin to build up an idea of what goes with what and why, you will very quickly be able to introduce this exciting dynamic element of organic gardening into you overall garden design.

In this series: ∙ Weed Control ∙ Compost ∙ Pest Control ∙ Companion Planting ∙ System Design ∙ Crop Rotation ∙