Companion planting – the plants to grow side-by-side

Companion planting is when you grow certain fruit and veg side-by-side with flowers for beneficial effects. With so many varieties of fruit and vegetables to grow, it can sometimes be overwhelming to know what to plant. But you can make the most of your garden by planting beneficial companions that can help improve home-grown produce by managing pests, promoting pollination, influencing soil nutrients and maintaining diversity.

And while there is little scientific research around this method of gardening, it is one that has been used effectively by farmers, and gardeners, for thousands of years. 

It also occurs naturally in nature, where certain plants grow together while others are never seen in each other's company. We can learn a lot from this and use companion planting in our own gardens – especially companion planting fruit and vegetables – to get healthier crops without the need for pesticides.

Below, we take you through some of the most useful companion planting combinations to help you make the most of your vegetable garden ideas. 

What is companion planting?

Companion planting simply refers to growing two or more different plants together for a beneficial effect, which is mainly used in the kitchen garden. 

So how does companion planting work?

• It promotes growth: Some companion plants actually help each other to grow and thrive, giving support, shelter and root space, enhancing the production, improving the taste, or creating better biodiversity.
• It deters pests: Others, sometimes called 'trap plants' attract pests towards them and away from your main crops; others taste bitter or are toxic to pests like aphids, so act as natural pest deterrents, such as Artemisia absinthium, tansy and pyrethrum daisies. Certain companion planting emits masking chemicals that deter detrimental insects, including rosemary, lavender and mint.
• It can be used to repel animal invaders: Don't just think of insects as pests; cucumbers can be used to get rid of raccoons for example; and there are snake-repellent plants, deer-resistant plants, rabbit-repellent plants and more.
• It attracts predators: From birds to insects, all of which will feast on pests, from slugs to aphids, these are the staple of wildlife garden ideas.
• It attracts pollinators: Many plants for pollinators attract bees and other pollinating insects, which improves the yield of vegetable gardens and is helpful for a balanced garden and eco system.
• It provides shade: Planting tall plants next to those that need shade is a simple way to adopt companion planting. Think: tall peas sheltering delicate salad leaves beneath. 
• It provides space: Each plant type needs a different amount of space to grow to its full potential. Matching fast-growers with slow-growers (think: speedy radishes next to slower parsnips) will give each the room it needs, rather than putting in plants whose roots will compete for space and nutrients.
• It avoids monocultures: These aren't a good way to grow, providing pests and diseases a happy breeding ground. Companion planting means bringing a wide variety of plants to your garden.
• It improves soil fertility: By companion planting, you can ensure the soil isn't depleted of nutrients but boosted. 
• It can suppress weeds: By filling gaps in borders with more planting, you are less likely to have weeds take over.
• It can improve flavor: Companion planting pairings to improve flavor include basil with tomatoes, borage to sweeten strawberries, and dill near corn.

What are the benefits of companion planting?

‘There is an array of benefits to companion planting in an organic garden. Companion plants help to protect the soil, suppress weeds, fill in any gaps and encourage biodiversity,’ says Emma O’Neill, head gardener at the charity Garden Organic.

The more diverse planting the better. A careful selection of plants and companions allows more variety in a small space, while helping you, the gardener, at the same time. Single crop garden beds can become plagued by insects, while mixing plants together confuses pests.

Charlotte Harris and Hugo Bugg have designed the kitchen garden at the new RHS Garden Bridgewater. Set within the historic walls of the original kitchen garden, it showcases companion planting.

‘We all do better with others in our lives and plants are no different, helping one another out, whether by acting as a lure, attracting beneficial insects or improving the soil. Importantly, companion plants are just as wonderful, beautiful and often edible – adding to the experience of your garden whatever the size of it,’ says Charlotte.

Gardening author and designer Marylyn Abbot likes to mix flowers, herbs and vegetables together in long lines at her West Green House gardens.

‘My first mission when I came here was to improve the soils and here companion and rotating planting assisted enormously. By planting a group of plants with different depth of root systems, this helped break up and improve the structure of the soils. A good example of this is planting carrots alongside tomatoes, plants whose roots go more deeply into the soil. Tomatoes are also a super decoy for keeping the rust fly from the carrots,’ Marylyn explains.

She adds: ‘Do choose plants that have good manners and do not encroach on each other’s space. By rotating crops and annuals the soil is not depleted of nutrients, and it is very enjoyable planting beautiful pictures in different vegetables and annuals each season.'

Companion planting vegetables and fruit

Below are examples of vegetables and plants that grow well side by side, either because they deter aphids, attract bees, attract hummingbirds and other pollinators, enrich the soil, attract pests away from the neighbor crop, or improve the flavor of the companion vegetable.

For instance, companion planting tomatoes with basil is said to improve the yield, attract whitefly away from the tomato plants, and may improve the flavor of the fruit. 

Equally, there are vegetables and flowers that you should avoid planting side by side. This may be because they compete for space, light, water, soil nutrients, or attract insects detrimental to the companion vegetables.

Companion planting chart

• Beans (French beans, runner beans, fava beans) – companion plant with corn, squash, carrots, summer savory, sweet peas, cabbage, beetroot. AVOID onion family, fennel, sunflowers
• Broccoli – plant with onions, chard, radishes, mint, spinach, beetroot, celery, sage, oregano, rosemary. AVOID tomatoes, squash, strawberries, corn, pumpkins, asparagus, peppers
• Carrot companion plants include onions, leeks, beans, brassicas, lettuce, peas, beans, sage, rosemary, tomatoes, melons, alliums. AVOID potatoes, dill, parsnips, celery, radish
• Cucumber companion plants include peas, beans, corn, radishes, onions, carrots, beets, cabbages, peppers, dill, oregano, nasturtiums, marigolds. AVOID potatoes, sage, melons
• Tomato companion plants include basil, mint, beans, lettuce, garlic, squash, thyme, French marigolds, calendula, chives, asparagus, nasturtiums, cosmos, amaranth. AVOID potatoes, brassicas, aubergine, peppers, fennel, kohlrabi, corn, dill
• Potato companion plants include horseradish, beans, basil, cabbages, corn, chamomile, alyssum, thyme, petunias, lamium, sage, nasturtium, coriander, tansy, nepeta, marigolds. AVOID squash, asparagus, nightshade family, fennel, sunflowers, raspberries, strawberries 
• Strawberry companion plants include asparagus, beans, borage, spinach, lettuce, garlic, onion, peas, thyme, horseradish, rhubarb, marigolds, chives. AVOID cauliflower, cabbages, broccoli, fennel, tomatoes, potatoes, melons, peppers, mint
• Peppers companion plants include carrots, cucumbers, endive, aubergine, allium family, asparagus, squash, basil, parsley, oregano. AVOID beans, brassicas, fennel, strawberries
• Onion companion plant include the cabbage family, tomatoes, lettuce, peppers, chard, strawberries, dill, parsley, mint, chamomile, summer savory. AVOID beans, peas, sage, asparagus
• Leeks - companion plant with carrots, onions, garlic, beets, celery, tomatoes, fruit trees, parsley. AVOID beans, legumes, swiss chard
• Kale companion plants include onion, garlic, leeks, peas, cabbage, lemongrass, chives, dill, nasturtiums, marigolds. AVOID other brassicas, such as brussels sprouts, broccoli, kohlrabi
• Zucchini companion plants include dill, lavender, chives, nasturtiums, oregano, borage, spinach, garlic, beans, peas, garlic, radishes. AVOID squash, pumpkins and potatoes

Flowers as companion plants

There are easy and attractive choices of flowers for companion planting with vegetables.

'Some of the best are marigolds, nasturtiums and calendula,’ says Emma O’Neill of Garden Organic. 

‘Nasturtiums help to deter aphids and are often used as a sacrificial plant so aphids and black fly attack them but stay away from your precious vegetables. 

'Calendulas are loved by bees and hoverflies, while the strong scent of marigolds confuses pests.’

Charlotte Harris and Hugo Bugg, also single out for attention the companion planting properties of hard-working and good-looking calendula, which they have included in the kitchen garden at RHS Garden Bridgewater.

‘Calendula not only glows with joyous orange from early summer to autumn,  but is a wonderful edible and medicinal plant that also repels whitefly from tomatoes, distracts aphids from crops and encourages beneficial insects,’ explains Hugo.

Calendula is in the Asteraceae family, a group that has a vital protein in its pollen that allows beneficial insects, such as hoverflies and lacewings, to lay viable eggs. 

Other good choices suggested include Erigeron karvinskianus, a wonderful, long-lasting and enthusiastic filler of gaps, Dyer’s chamomile, and sunflowers. 

Companion planting herbs

Mix herb garden ideas, particularly aromatic herbs, including thyme, oregano, rosemary, mint and lavender companion plants through your plot to help repel insects with their aromatic foliage and to attract pollinators.

Organic grower, designer and author, Jekka McVicar VMH, of Jekka’s Herb Farm, has a holistic approach to using herbs in the garden. ‘I have more success when herbs are planted to attract a wide range of pollinators, which improves the yield, rather than as specific companion plants,’ explains Jekka, who intermingles vegetables and an array of self-seeding herbs in her private garden.

‘As herbs heal us they can also heal other plants; for example, chamomile next to an ailing shrub is a natural anti-fungal,’ she adds.

What is a companion planting method?

Try the 'Three Sisters' method: some companion planting combinations offer a physical advantage – for example the ‘Three Sisters’ method with beans, corn and squash. Beans use corn as a support while fixing nitrogen at their roots; squash sprawls and helps cover weeds.

Which is the best companion plant? 

Marigolds are useful companion plants to just about any vegetable you care to plant. Plus, they look pretty. Plant marigolds to keep bugs away and suppress plant-parasitic nematodes that attack the roots of vegetables. They are often used with tomatoes to improve their yield.

You can also interplant strawberries with vegetables and herbs to conceal them from birds and pests. Use legumes, which help other crops by releasing nitrogen into the soil. Plant peas: fruit bushes and trees planted with peas, beans and sweet peas will flourish – the nitrogen from pea family roots benefits fruit

What shouldn't you plant together?

Separate members of the same plant family shouldn't be planted together – growing them next to each other increases competition for soil nutrients, so it is best to scatter them across your vegetable garden.