The benefits of companion planting

Companion planting creates communities of plants that help each other to thrive naturally. It’s a way of gardening organically, and sustainably, by seeking  natural ways to reduce pests without using pesticides, improving the soil and increasing yields of fruit, flowers and herbs.

In practice it is the interplanting of flowers, herbs and vegetables, and is a great option for small gardens and can even be used when planting up pots.

Sowing of companion vegetables, herbs and flowers can start in September or earlier in August if seed trays are kept in a warm, sheltered area. While the seed is growing prepare the soil by digging in plenty of compost.

Kirchhoffs has a large range of heirloom open-pollinated, non-GMO varieties for organic gardening.

There are three basic components to companion planting:

Flowers or flowering herbs that attract pollinators

Fruiting vegetables like tomatoes, squash, eggplant, peppers and cucumber need to be pollinated by insects such as bees and butterflies. They are attracted by nectar rich flowers such as alyssum, asters,  cornflowers, California poppies, dahlias, snapdragons and  zinnias.

Flowering herbs like borage, basil, dill, lavender, oregano and  thyme will also draw the pollinators.  Such plants are also likely to attract beneficial insects like lady birds that feed on aphids.

Pest repelling plants

Herbs with  strongly aromatic leaves like lavender, thyme, sage, basil, and garlic chives tend to repel or deter  pests, especially when planted around or next to vegetables or flowers susceptible to aphids, thrips and other sucking insects. Fennel and act as trap crops attracting the pests to their flowers and away from the vegetables. Marigold roots emit a substance that deters nematodes.

Plants that improve the soil

Herb doyenne Margaret Roberts used to refer to Chamomile as the plant doctor because if it benefitted any plant that was grown next to it. Lovage is another herb that is beneficial to plants and its leaves are delicious in stews and soups.

Legumes like beans and peas fix nitrogen in the soil. Mustard can be sown as a green manure to fumigate the soil that has been infected with pathogens.

Borage, yarrow and comfrey are mineral-rich herbs. They can be used as a soil improving mulch or as a compost activator in the compost heap.

Good  and bad companions

If you want to find out more, google is your quickest and widest research tool. The are many companion planting sites, but you might find that they don’t all agree. A safe bet is where there is consensus among sites about the companion properties of a particular herb or herb/veggie combination.

Good companions

For a quick start, you can’t go wrong with these good companions:

• Tomatoes with sweet basil. Basil repels pests like white fly and improves the flavour of tomatoes.
• Lettuce and radishes: radish roots and leaves deter insects and act as a tonic for tender vegetable like lettuce.
• Beetroot and marigolds. Marigolds repel soil nematodes which attack the roots of plants.
• Alyssum and sweet peppers. Alyssum attracts pollinators as well as predatory wasps, lady birds and lacewings, all of which feed on aphids and other pests that might damage pepper plants.
• Green bush beans and rocket. Green beans fix nitrogen in the soil and improve the flavour of rocket.
• Cucumber, nasturtiums and runner beans. Beans fix nitrogen in the soil which benefits cucumbers and runner beans can be grown vertically alongside cucumbers which saves space. Nasturtiums act as a trap crop for aphids and the flowers and leaves are edible.
• Chives and carrots. Carrots grown next to chives are generally healthier and sweeter and chives repel aphids.

• Sunflowers and sweet corn. Sunflowers act as a trap crop for stinging insects and attract pollinators. They will also shade cucumbers, which can grow up the sunflower stem.
• Borage and eggfruit. Borage flowers attract bees to pollinate the eggfruit flowers and its dense growth acts as a groundcover to keep the soil moist.

Bad companions

Not all plants are good companions, so it is important to know which plants work well together and which don’t. For instance, some plants inhibit the growth of other plants. Plants that both have high nutrient demands will compete for the same resources. Nor should those that are affected by the same pests and diseases be planted close to each other.

Here are some examples of plants that don’t like each other and should not be planted together:

• beans and onions
• brassicas and tomatoes
• carrots and fennel
• cucumbers and potatoes
• watermelon and mustard

A helping hand

Should mid-summer see an overload of pests, the healthy option is targeted spraying (only on pest infected plants) with an organic insecticide like Ludwig’s insect Spray + or Margaret Roberts Organic Insecticide.

For more information, visit the Kirchhoffs website.

Article and images supplied by Alice Coetzee.

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