Companion Planting Guide | Thompson & Morgan (2024)

Companion planting is all about creating plant communities which have mutual benefits to each other. It can be an organic way to protect your crops from pests or it could help improve pollination of fruit and vegetable crops. Although there is limited scientific research surrounding companion gardening, many gardeners find it extremely beneficial to their plant’s performance. In this article we've put together the best known partnerships in flowers, herbs and vegetables to help you improve the health of your garden plants without needing to resort to pesticides. Take a look at our companion planting chart below.

Companion planting hints and tips

Avoid monocultures. This is where the same type of plant is grown en masse or in rows. Monoculture makes it much easier for pests and diseases to find their favourite plants and then spread quickly.
Use tall plants such as peas or sweet corn to create partially shaded conditions for crops prone to bolting, such as coriander, lettuce and spinach.
Plant herbs throughout the garden and vegetable plot, as most have strongly scented leaves which help repel insects.
Try intercropping. This is where fast-growing crops such as lettuce or radishes are sown between widely spaced rows of slower-growing crops such as Brussels Sprouts or parsnips. It utilises the space available and helps prevent weeds growing (weeds take nutrients, light and water, and spread disease).
Plant lots of insect-friendly or bird-friendly plants, either amongst your crops or nearby. They attract natural predators such as birds which eat slugs, hoverflies which eat aphids and bees which pollinate your crops. For a list of wildlife-friendly plants click here.
Take care with some companion plants such as mint - these are fast-growing plants and will quickly smother your crop. Grow mint in containers to keep it under control.

Companion planting chart

Companion plant 1	Companion plant 2	How does it work
Cabbage, kale, cauliflower	Nasturtium	Plant Nasturtiums as a sacrificial crop. Cabbage white butterflies will lay their eggs on Nasturtium plants, keeping caterpillars away from your Brassicas.
Cabbage, kale, cauliflower	Mint	Mint helps to deter flea beetles, which chew irregular holes in the leaves.
Courgette	Calendula (English Marigold)	Calendula flowers are highly attractive to pollinating insects which will in turn pollinate your courgette flowers.
Broad beans	Summer savory	Summer savory helps to repel blackfly, a common pest of broads beans.
Carrot	Spring onions	Sow spring onions amongst your carrots - the smell of onion deters carrot root fly. The smell of carrots also deters onion fly from onions.
Carrot	Leek	The smell of leeks deters carrot root fly. The smell of carrots also helps deter leek moth from leeks.
Carrot	Mint	The aromatic leaves of mint help confuse carrot root fly, who find their host through scent.
Chrysanthemum	Chives	The onion scent will deter aphids.
French /Runner beans	Nasturtium	Plant Nasturtiums as a sacrificial crop - aphids love them and this will lure them away from your runner beans/French beans.
Onion	Mint	The aromatic leaves of mint help to confuse and deter onion fly.
Radish	Mint	Mint helps to deter flea beetles, which chew irregular holes in the leaves.
Roses	Garlic	The smell of garlic helps to deter aphids.
Roses	Mint, Chives , Thyme	The strong scent of these herbs deters aphids and blackfly.
Runner beans	Sweet peas	Sweet peas will attract pollinating insects which will in turn help to pollinate your bean flowers.
Sunflower	Chives	The onion scent will deter aphids.
Tomatoes	Mint	The smell of mint deters aphids and other pests.
Tomatoes	French Marigold (Tagetes patula)	The pungent smell of French marigolds deters whitefly.
Tomatoes	Chives	The onion scent will deter aphids.
Tomatoes	Basil	Basil reportedly improves tomato flavour and the strong scent of their leaves also deters aphids. A perfect partnership in the kitchen too!

Quick Links:

Encourage wildlife to your garden
Plants for wildlife
Garden pests and diseases

Written by: Sue Sanderson

Plants and gardens have always been a big part of my life. I can remember helping my Dad to prick out seedlings, even before I could see over the top of the potting bench. As an adult, I trained at Writtle College where I received my degree, BSc. (Hons) Horticulture. After working in a specialist plantsman's nursery, and later, as a consulting arboriculturalist, I joined Thompson & Morgan in 2008. Initially looking after the grounds and coordinating the plant trials, I now support the web team offering horticultural advice online.

Insights, advice, suggestions, feedback and comments from experts

Companion planting is a gardening technique that involves creating plant communities with mutual benefits for each other. It can help protect crops from pests and improve pollination of fruit and vegetable crops. While there is limited scientific research on companion gardening, many gardeners find it to be extremely beneficial for their plants' performance.

Benefits of Companion Planting

Companion planting offers several advantages for gardeners. By implementing companion planting techniques, you can:

Protect crops from pests: Certain plants can repel or deter pests that may damage crops. For example, planting mint alongside cabbage, kale, and cauliflower can help deter flea beetles, which chew irregular holes in the leaves [[1]].
Improve pollination: Some companion plants attract pollinators like bees, hoverflies, and birds, which can enhance the pollination of fruit and vegetable crops. For instance, planting calendula (English marigold) near courgettes (zucchini) can attract pollinating insects that will in turn pollinate the courgette flowers [[2]].
Create shade and prevent bolting: Tall plants like peas or sweet corn can be used to create partially shaded conditions for crops that are prone to bolting, such as coriander, lettuce, and spinach [[3]].
Utilize space and prevent weeds: Intercropping involves sowing fast-growing crops like lettuce or radishes between widely spaced rows of slower-growing crops like Brussels sprouts or parsnips. This technique helps utilize space efficiently and prevents weed growth, as weeds compete for nutrients, light, and water and can spread diseases [[4]].
Attract natural predators: Planting insect-friendly or bird-friendly plants near or among your crops can attract natural predators like birds, hoverflies, and bees. These predators can help control pests like slugs and aphids, as birds eat slugs, hoverflies eat aphids, and bees pollinate crops [[5]].

Companion Planting Chart

Here are some examples of companion planting partnerships:

Cabbage, kale, cauliflower + Nasturtium: Planting nasturtiums alongside cabbage, kale, and cauliflower can act as a sacrificial crop. Cabbage white butterflies lay their eggs on nasturtium plants, diverting caterpillars away from your brassicas [[6]].
Cabbage, kale, cauliflower + Mint: Mint can help deter flea beetles, which can damage the leaves of cabbage, kale, and cauliflower [[7]].
Courgette + Calendula (English Marigold): Calendula flowers are highly attractive to pollinating insects, which can help pollinate courgette flowers [[8]].
Broad beans + Summer savory: Summer savory can help repel blackfly, a common pest of broad beans [[9]].
Carrot + Spring onions: Sowing spring onions among your carrots can deter carrot root fly, as the smell of onion deters them. Additionally, the smell of carrots can deter onion fly from onions [[10]].
Carrot + Leek: The smell of leeks deters carrot root fly, while the smell of carrots deters leek moth [[11]].
Carrot + Mint: The aromatic leaves of mint can confuse carrot root fly, which find their host through scent [[12]].
Chrysanthemum + Chives: The onion scent of chives can deter aphids [[13]].
French/Runner beans + Nasturtium: Planting nasturtiums as a sacrificial crop can lure aphids away from your runner beans or French beans [[14]].
Onion + Mint: The aromatic leaves of mint can confuse and deter onion fly [[15]].
Radish + Mint: Mint can help deter flea beetles, which can damage the leaves of radishes [[16]].
Roses + Garlic: The smell of garlic can help deter aphids from roses [[17]].
Roses + Mint, Chives, Thyme: The strong scent of these herbs can deter aphids and blackfly from roses [[18]].
Runner beans + Sweet peas: Sweet peas can attract pollinating insects, which can help pollinate bean flowers [[19]].
Sunflower + Chives: The onion scent of chives can deter aphids [[20]].
Tomatoes + Mint: The smell of mint can deter aphids and other pests from tomatoes [[21]].
Tomatoes + French Marigold (Tagetes patula): The pungent smell of French marigolds can deter whitefly from tomato plants [[22]].
Tomatoes + Chives: The onion scent of chives can deter aphids from tomatoes [[23]].
Tomatoes + Basil: Basil reportedly improves tomato flavor, and the strong scent of its leaves also deters aphids [[24]].

Remember, companion planting is a technique that can be used to enhance the health of your garden plants without relying on pesticides. It's important to note that while many gardeners have found success with companion planting, the scientific research on its effectiveness is limited. However, it remains a popular and widely practiced technique among gardeners.

I hope this information helps you improve the health of your garden plants through companion planting! Let me know if you have any more questions.