Companion planting is an acceptable and environmentally friendly solution in controlling insect pests. In nature plant species do not grow close together in rows but happen spontaneously. This companion growing, explained in scientific terms, is called “natural selection“, and can be applied to the home garden.
Certain plants grow harmoniously side by side, because different plants give off substances through their leaves and roots which complement the needs of their neighbor.
Some of these compatibilities have been proven to be physical or chemical reactions – tall-growing plants like corn will protect shade-loving plants such as watermelon and cucumbers, while marigolds give off a substance through their roots which repels nematodes (eel worms) .
Other plants, for instance garlic, enjoy a high reputation in the garden for repelling insect pests when grown among other plants. Agriculturists of old used to plant garlic near their onions, cabbages and garden vegetables to keep away various flies and grubs.
Today, organic gardeners have found that highly diluted garlic extract kills or keeps away wireworm, caterpillars, weevils, black fly, Japanese beetles, aphids and other leaf-sucking bugs. It is also useful against fungi such as mildew, bean rust, anthracnose, brown rot and blight.
Mustard is also an excellent all purpose pesticide. Grow a bed of it, and when in flower cut it and dig into the ground to eliminate insect pests and their eggs.
Another important garden herb to grow in among other plants is cayenne chili. Not only will it help to discourage many insect pests, but when dried and powdered it can be dusted on fruit trees before the fruit ripens to discourage fruit fly and other pests that may affect the fruit. It can also be used to dust cabbages, cauliflowers, and tomato plants to kill caterpillars.
When grinding up the cayenne chili be sure to wear rubber gloves, and do not touch your face, mouth or eyes – it burns and irritates for quite a long time.
Grind up the chilies using a pestle and mortar, or process in a blender, until reduced to a powder, and store in a suitable container with holes in its lid. Use as required.
When planting your garden, for best results grow shallow rooted plants near deep rooted species, and leafy crops with root crops – this way they are not competing for the same ground space or specific nutrients.
Species with different water requirements will also do well together, since they will not be competing with each other. This equally applies with plants of different nutrient requirements.