Companion Planting and Disease Prevention

Jun 04, 2014

By Margaret Inwood, Lanark County Master Gardeners

Companion planting is the practice of planting certain plants with others in the hope of repelling bugs. Many gardeners swear by the power of garlic, marigold, onions, chives, and nicotiana in keeping their immediate neighbours free of insect infestations.

Some other suggestions to use as companion plants are basil, catnip, celery, dill, flax, geranium, hyssop, horseradish, nystertium, parsley, sage, peppermint, tansy, thyme, and tomato. Interplanting beans and potatoes help reduce injury from Colorado potato beetles and leaf-hoppers. As a method of pest control, avoid close planting of highly competitive densely foliated plants near the crops. For example, avoid planting marigolds, catnip, celery, tansy, and tomato as companions unless sufficient space is allowed. Avoid companion plants which could serve as alternative hosts for pests and diseases of the crop. For example, flea beetles will attack nysteriums, as well as cabbage.

Choose plants of aesthetic or culinary importance which could also provide enjoyment or food. Leave some of the crop without companion plants, to objectively assess whether or not any benefit is resulting from this technique.

One can also reduce the danger to your crops from insects and disease by crop rotation. Also, all plant refuse, including large weeds, should be gathered and destroyed in the garbage.

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