Inch by Inch: Plant partners

Posted Wednesday, April 18, 2012 in Features

Inch by Inch: Plant partners

The three sisters — corn, squash and beans — is one of the most famous of the plant partnerships.

This week, we're going to look at some simple ways you can keep your soil healthy and grow healthier plants at the same time. We'll also look at some legitimate plant partners who can keep away some of the insect pests you absolutely don't want, especially if you are going organic.

This is a quick look, but if you want to get a lot of in-depth information about the subject, a good book is "Carrots Love Tomatoes" by Louise Riotte.

Pollination Partners

As you probably know, to set fruit, plants require pollination. For most vegetable gardeners, all you may need are some bees, so growing a small crop (or allowing to grow as 'weeds' in your lawn) of clover is a good idea. Bees are attracted to clover, which happens at about the same time as most vegetables and fruits ... cucumbers, tomatoes, squashes, melons, berries, many peppers, etc. ... produce their flowers. But a few clover plants do not a hive make, so the bees will also visit your flowers to collect additional nectar. You'll be far more likely to have a full crop if you have a little clover growing nearby.

While most vegetables and many fruits can self-pollinate ... that is, the bees can visit one flower after another and you will get a tomato or watermelon ... some fruits and vegetables need another organism of the same or a similar species in order to grow. Among the vegetables, asparagus is a perennial, but in order to keep a healthy asparagus bed, you need both male and female plants. In fruit trees, another plant, occasionally another variety altogether, is required. Apples, for instance, do not pollinate in the same variety; the grower needs two or three trees of differing varieties to produce the grafted variety the gardener wants. If you want Macs, you have to have another type of tree ... say, Gala ... to fertilize your Macs. The Macs may or may not fertilize the Gala. Before planting an orchard, visit a nursery and find out when the trees you want flower, so you can get a pollinating partner that will actually do the trick.

Some plants are grown near others because they encourage pollinators. For instance, pear trees are often fertilized by hummingbirds, so planting a trumpet vine near your pear tree will encourage hummers and give you a full crop.

Soil partners

A lot of plant partners, like the three planted together in the photo above, provide services to one another. The beans fix nitrogen, which is needed by the nitrogen-greedy corn. The corn serves as a beanpole for the climbing beans and squashes, and the squash is a good groundcover that prevents dehydration.

Other partners, like the tomatoes and carrots suggested by the title of Riotte's book, partner well together. Tomatoes have an anti-fungal in their green leaves that is transferred to the roots, and this protects the carrots from fungus present in the soil. They are a good pH partner, because tomatoes like acid, while carrots prefer slightly alkaline soil, so it is possible to grow both in the same bed without having to fertilize. 

Other partners include watermelons and potatoes, sweet pepper and okra, peas and cucumbers, and onions and cabbages. You might also try lettuce growing together with strawberries, as long as you are planting early strawberries. 

Natural insect repellent

Growing marigolds in tomato beds (and in peppers, cucumbers, corn, and even among strawberries) is a powerful deterrent for some pretty nasty bugs that can blight your garden for years to come. The problem is that it won't all happen in one year. Marigolds provide nematode control in the soil, and hornworm control in tomatoes and corn. It can also lessen the effects of fungal blight in the soil, but you will probably have to still treat your plants with copper if you get an early or late blight. 

Planting a couple of radishes with squash and cucumbers will keep squash bugs at bay. Let the radishes go to seed. 

Growing garlic in a tomato bed will keep red spider mites away from your tomato roots.

For one of Maine's worst pests, the Japanese beetle, learn to love chrysanthemums. Grow them with virtually everything the beetle likes: grapes, roses, herbs. Grow them in borders around your fence to help kill grubs in the soil. If the plants don't work by themselves, you can get a completely non-poisonous chrysanthemum spray to spray directly on the little beasts, but it's best to discourage them with the flowers, first. Lavender, too, is not beloved of the Japanese beetle.

Chrysanthemums have other uses, too. Try the white flowering hardy chrysanthemums, which you can order and plant early in the season. They repel many garden pests, but must be planted in full sunshine.

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