Companion Planting

 In Garden Design, News

The conventional approach to the way we layout our gardens is to have the structural planting combined with the pretty, colourful perennial plants close to the home so that we enjoy the views. The kitchen garden tends to be screened away and if any of us are truly fortunate then we may even have a small orchard at the very rear of the garden. Is this the best approach to the layout of our gardens especially when we take into consideration the environment, wildlife, use of chemicals, and the increase in pests and diseases.

companion planting
Photo Credit: Photo Teatro and Xylellacodiro.blogspot.com

This image shows the effects of Xylella fastidiosa on Olive orchards in Puglia. Whole orchards have been destroyed by one single pest.

Monoculture is one the most negative methods of planting, mainly used in the agricultural industry due to the increase in human demands. A single variety grown in vast blocks becomes a feast for a pest or disease that is specie specific. A good example of this is the fields of Olive trees in Puglia that have been devastated by Xyllela fastidiosa. The direct knock-on effect of this is that the lively hoods of whole families have diminished. Large sections of the world’s rain forests being destroyed for growing Palm trees because nearly everything that we buy from soaps, shampoos, detergents to certain foods includes palm oil. What happens if the palm beetle destroys these plantations? We end up with areas of this earth that become open to erosions or turn into deserts. This would cause devastation.


Credit: Future Learn. Photo Credit: Adiartana

Whilst this image may look beautiful with lots of lush palm trees, there is something very disturbing as well. Vast areas of natural forest have been cleared to grow these palm trees. Virtually everything that you buy from supermarkets these days has palm oil. It would only take one specie specific pest or disease to wipe out all of these palm trees. This is monoculture and it is the most negative method of planting.

What can we consider in our gardens? Whilst we can use chemicals to control pests and diseases is this really good practice? Chemicals may get of rid of the bad critters, but they also harm the good insects and wildlife that we do want in our gardens. Could the answer be to create an environment within our gardens where plants and wildlife live in harmony to benefit each other?

Companion planting is a more spiritual and organic approach to gardening. The underlying belief is that all things on this earth are connected. Can you imagine a world where fungi and insects did not exist? What would happen to all the leaf fall during autumn? We would be buried underneath it all. Companion planting has existed from the time when humans started growing their own crops. The Native American Indians called it ‘three sisters’ where they used to grow corn, beans, and squash together. The corn stems provided support for the beans to climb whilst the squash covered the ground acting as a mulch, preserving moisture in the ground, keeping weeds at bay, and also adding nitrogen in the soil which benefits the other plants. Successful companion planting comes through experimenting. The rewards of companion planting can be better plant health, increase in crop yield, deterring and repelling pests, attracting beneficial insects, reducing weeds, preventing disease, and adding goodness back into the soil. It also means the reduction or total elimination of chemical use saving us money and time.

An example of companion planting. The marigolds will help to repel pests but will Also, attract beneficial predatory insects. This reduces the need to use insecticide sprays. The basil will improve the vigour and flavour of the tomatoes.

Different species of plants grow in nature side by side successfully. Monoculture is a human invention that is completely out of tune with nature. Get companion planting right for your particular environment and you will find that you will be able to reduce or eliminate the use of pesticides and other chemicals.

Most people associate companion planting with kitchen gardens but that does not have to be the case. If you have a small garden, you may not have space for a separate kitchen garden. If this is the case, grow your fruit and vegetables as part of the overall planting scheme within the garden. If you are growing brassicas, grow Agastache nearby to attract the cabbage moths away from the brassicas. Agastache attracts bees too. The varieties of Ammi are all very pretty, but they also attract predatory insects such as lacewings, ladybirds, and parasitic wasps. This is the sort of wildlife you want in your garden. The most popular crop that gardeners grow is tomatoes. Grow Basil with your tomatoes and it will improve vigour and flavour. Basil makes a great companion for asparagus, oregano, and peppers. It repels aphids, mites, flies, asparagus beetles, and tomato horn worms. Grow marigolds (this includes calendula) with tomatoes as they will repel pests such as whitefly, root-knot nematodes and root legion nematodes. Marigolds also attract hoverflies and parasitic wasps Calendula is also edible. It can be used in salads, omelets, and ice cubes to give your drinks a spark of colour.

Plants that will attract beneficial insects and pollinators
Top Row from left: Rudbeckia, Dill, and Tithonia
Bottom Row from left: Echinacea, Ammi Majus, and Cosmos

Mint is a very beneficial plant to have in the garden. It can get rampant so grow in containers and place it near the plants you want to protect. Mint attracts ladybirds which feed on aphids and greenflies. It also attracts hoverflies and predatory moths but repels cabbage moths and aphids

Growing plants that attract beneficial insects create biodiversity and wildlife habitat in our gardens. We need to attract both predatory and pollinating insects into the garden and the best way to do this is by growing a mix of plants. Open blooms are the best for insects as they can get to the nectar. Don’t forget to add plants that produce seeds and berries into your mix as these are good for the birds who will also keep pests at bay.

Cosmos which is a lovely annual attracts lacewings, ladybirds, damselflies, and other predatory insects that will help with pest control. Dill attracts ladybirds, parasitic wasps, hoverflies, and spiders but bees also love it. Echinacea is also good for hoverflies and parasitic wasps. Fennel attracts hoverflies, parasitic wasps, ladybirds, and tachinid flies. However, Fennel is not a great companion for other food crop plants so plant it separately. Iberis is a good source of nectar for pollinators but it will also attract hoverflies and ground beetles. Lovage will attract parasitic wasps and ground beetles. Rudbeckia not only looks attractive and provides bursts of colour in a planting scheme but also attracts hoverflies and parasitic wasps. Tithonia have a long flowering period and make great plants for the back of a border or in containers. They will attract parasitic wasps, parasitic flies, and stinky bugs which are predators of gypsy moth caterpillars and the larvae of beetles.

The plumes of Amaranth a very pretty. If planted in rows, not only will they compete with weeds but help conserve moisture in the ground. Phacelia is pretty and makes a good weed suppressant. It is also good for improving the soil structure and draws in bees and hoverflies. Nasturtiums are colourful and edible, but they also make a good trap crop for aphids whilst deterring whiteflies and certain beetles that damage cucumber and squash. Grow nasturtiums with cucumbers, squash, tomatoes, radish, brassicas, and melons. They are also good for bees and other pollinators.

Onions, garlic, and leeks will all help to repel carrot rust flies. Garlic repels aphids making it a good companion plant for roses. The sulphur compounds will also help repel whiteflies, carrot rust fly, and other pests. You can also turn garlic into a spray and a systemic pesticide to be used on plants that are prone to slug and snail damage. Garlic makes a good companion plant for lettuce, tomatoes, celery, strawberries, and brassicas but not peas and beans.

Remember some plants will take a lot of goodness out of the soil, such as brassicas. It is therefore important to look at how we can add goodness back into the soil. The long roots of vetch help fix nitrogen into the soil. Digging the plants into the soil will also provide lots of organic matter. Whilst we may not want nettles in the garden, let’s keep in mind that nettles can make a good liquid feed for plants. Last but not least is composting. Creating your own organic compost is like gardening gold.

Companion planting is a little bit about the science of horticulture, but it is a lot about what works in your garden. The best way is to experiment and make notes of what works and what doesn’t. This way you will make improvements every year.

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