Companion planting is the clever gardening hack you need to banish pests

Companion planting is one of those timeless garden ideas that every green-fingered soul should know about.

You've likely heard the term before: after all, it's one of those enduring garden trends that pops up time and time again. But what is companion planting, really? And why do so many tout it as a surefire route to bringing balance to even our most modern garden ideas?

What is companion planting?

Companion planting, as you've likely guessed from the name, is all about planting combinations of specific plants for their mutual benefit – a sort of plant buddy system, essentially.

'Companion planting means planting a variety of plants or crops in close proximity to each other, instead of just growing one type,' explains Catherine Capon.

Catherine Capon

Catherine Capon is a British Naturalist and Environmental Activist who is passionate about rewilding and responsible ecotourism. Catherine studied ecology and zoology at Imperial College London which has led to her career in wildlife filmmaking and environmental campaigning. Catherine is a trustee of The European Nature Trust and the Big Blue Foundation, and is currently communications consultant for the UK at digital tree planting platform, Treedom. 

Urging people to avoid creating a monoculture within their gardens, Catherine explains that the theory behind companion planting is that certain plants will form alliances, helping one another to not just survive, but thrive.

'It's a similar concept to the regenerative farming method of agroforestry that Treedom uses, where trees are deliberately grown amongst traditional agricultural crops.'

What are the benefits of companion planting?

Companion planting is absolutely something worth considering when figuring out how to plan a garden, as there are a number of surprising benefits to this age-old gardening technique.

For example...

1. It can repel garden pests

Whether you're trying to figure out how to grow tomatoes, the best vegetables to plant in shade, grow lavender in garden borders, plant a rose arch, or grow raspberries in pots, companion planting is a must-know tip.

'The right combination of plants can help to repel pests, without the need for harmful pesticides,' says Catherine. 

For example, planting marigolds near vegetables can help deter aphids, while popping garlic, onions, or chives in a row alongside carrots will deter carrot fly. 

Those who are fond of edimentals will be pleased to know that a bed of nasturtiums alongside your brassicas will protect them from caterpillars. 

Meanwhile, the strong scent of potted mint helps to deter flea beetles, while dill and fennel can help to attract aphid-chompers such as lacewings and ladybirds. And there are plenty more ways to use companion plants as a means of repelling pests, too.

2. It keeps weeds at bay

'Companion planting keeps the weed away,' says Catherine. 

'Planting something under a tall vine, for example, can stop that vacant space from filling up with weeds. And mixing tall and short plants is also a great way to utilise a small space and allows taller plants to give shade to smaller ones that don’t like direct sunlight.' 

3. It can prevent disease

'Companion planting is a great way to stop disease taking hold of your flowers, fruits, and vegetables,' says Christopher O'Donoghue, one of the co-directors at Gardens Revived.

Alliums, camomile, and nasturtiums are said to prevent fungal infections such as cane spot.

4. It attracts pollinators

There's a reason so many of us are obsessed with sourcing bee garden ideas.

'Companion planting is a brilliant way to attract useful pollinators,' says Christopher, noting that many crops tend to yield better results if they've been visited by bees and butterflies.

To attract pollinators, try planting bee-friendly herbs (such as dill, lavender, fennel, and parsley) near melons, raspberries, strawberries and squash.

Doing so should create plenty of reasons for bees to visit and give your plants a boost.

5. It can prevent sun damage

'Planting trees amongst crops (agroforestry) prevents them from sun damage, as well as protection from heavy rain and wind,' says Catherine.

What plants work well together in smaller gardens?

In smaller gardens where there isn’t enough room for trees and larger plants, companion planting can still be very effective.

'Planting basil near tomatoes can repel whiteflies and tomato hornworms whilst also improving the flavour of the tomatoes,' explains Catherine. 

'If you’re looking to bring some life to your garden, planting flowers near vegetable crops can help to attract butterflies and bees for improved pollination.'

'Planting lettuce amongst plants such as chives and garlic can help to repel aphids (a common issue for lettuce),' continues Catherine. 'Marigolds are also a great pest repellent for lettuce.

'And alyssum isn't just an annual that's easy to grow from seed; planting it between leafy greens attracts hoverflies – a natural predator of aphids.'

Companion planting tips for beginners

If you are enamoured with the idea of companion planting, but not sure where to start, don't worry: Catherine has some easy tips for you to try.

• Start small: If the thought of companion planting sounds overwhelming or complicated then you can always just start with growing two plants in a single bed or box that you know will have mutual benefits. Once you have mastered this, you can start to expand the rest of your garden.

• Know your plant: Plants have different light and water needs, if you can understand what your plant needs you can think more carefully about where to plant it and what to plant it with. For example, would the plant benefit from the shade of a larger plant, or does it want direct sunlight? 
• Mixes to avoid: Certain combinations of plants may not thrive together, so make sure you have done your research. For example, dill and carrots because the dill can cross pollinate and impact the taste of the carrots. Similarly, potatoes and tomatoes aren’t a good pair because they compete for the same nutrients and attract the same pests. 

Essentially, it seems that all the old adages are true: a good friendship will enrich anyone's life – even if that 'anyone' is a plant. Go figure.

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