Why Plants Make Good Neighbours

Backgrounder

Plants can be good neighbours or bad neighbours. Some plants help each other and grow stronger when they are planted together. Some people call them good companions. Other plants growing next to each other do not benefit one another. In fact they may grow poorly side by side. They are bad neighbours and should not be planted together.

Farmers have been choosing good neighbours to plant together since the beginning of agriculture. In the Americas, squash, corn and beans have been planted together for hundreds of years. They are known as the “three sisters”. When planted together each crop yields much more than when it is grown separately.

Today we’re going to talk about how to choose crops that make good neighbours. This is sometimes called companion planting.

There are different reasons why plants do or do not get along well together. Today we’ll talk about some of these reasons. We’ll also give you examples of good and bad plant combinations that farmers and gardeners have discovered.

To begin, let’s talk about the shape of plants, and the space they need. You might have noticed that some plants do well growing near each other because of their different shapes or the way in which they grow. For example, a tall sun loving plant, such as corn, provides shade for a shade loving crop, such as cucumber. The corn also benefits from the cucumber vines which cover the ground and protect the soil.

Let’s look at another example. Vegetables which mature quickly can be grown beside vegetables which mature slowly. For example, carrots and radishes do well together. As you pick the fast growing radishes, the carrots have more space to grow. Try to find ways which crops can be arranged so that they don’t need to compete for space. This way, each plant will have room to grow big and strong.

Some plants are good neighbours because they take different amounts of nutrients out of the soil. Most of the vegetables we grow – such as tomatoes, squash, lettuce, and cabbage – take a lot of nutrients from the soil. On the other hand, some plants take fewer nutrients from the soil. For example, legumes such as beans, peas, lentils, and clovers take less nitrogen from the soil. They take nitrogen from the air instead. So legumes are good companion plants for many crops because they don’t compete for nitrogen in the soil.

When you’re choosing plants to grow together remember that different plants have different needs. Some crops need more sun or water than others. They need different nutrients. Some need more space for their roots, and some need more above ground space. If you keep this in mind, you’ll probably be able to think of other good plant combinations.

By choosing good companion plants you can also reduce insect damage. Crops with strong odours, such as onions and garlic, can repel some harmful insects. So plant garlic and onions with other crops. For example, cabbages and garlic are good neighbours. Insects will probably attack a plot where only cabbages are growing. But they are less likely to attack a mixed plot of cabbage and garlic.

Herbs and flowers with strong smells, such as mint, thyme, basil, marigolds and nasturtiums, can be useful companion plants. Their strong odours repel insects and may discourage them from landing in the garden. For example, marigolds are widely used to repel nematodes, Mexican bean beetles, and other insects.

So you can see that some plants provide a pest control service for one another.

And remember that the more kinds of plants you have growing in one area, the more stable your yields will be. Some crops will survive even if you have bad weather or poor soil, or an attack by pests. So the more variety of crops you have, the safer you are.

Many of the ways that plants can help other plants are still not well understood. A lot more research needs to be done by both farmers and scientists. As you think about which plants to grow together, keep an open mind. Keep trying different combinations until you find a system that works for you.