What is companion planting?
Companion planting is an organic method of maintaining a natural balance in your garden by growing plants together that are mutually beneficial. Planted together, certain plant combinations can aid pollination, prevent disease and keep pest numbers down. Most companion plants are strongly scented and can confuse pests looking for their host plant, some have antibacterial or anti-fungal properties, while others attract beneficial insects, such as ladybirds and lacewings, which prey on aphids. Most companion planting occurs in the vegetable patch, but some ornamental plants, such as roses, can also benefit from particular plants growing nearby.
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Common plant combinations include growing nasturtium to deter aphids from beans, and planting alliums around carrots to ward off carrot root fly.
What are the benefits of companion planting?
Companion planting can help your plants to grow better and with fewer pests and diseases. Ultimately this benefits the gardener as this means less work for higher crop yields.
Plant combinations to avoid
There are some obvious plant combinations to avoid, for example you should avoid planting tall plants next to shorter plants, as they will block light and prevent them from growing well. Growing thirsty plants next to drought-tolerant plants is also not advised, as one plant will either be getting too much water, or too little.
Some plants appear to have what's known as allelopathic properties. This means that the plants release chemicals that inhibit growth of other plants. One of the most commonly known plants thought to be allelopathic is the walnut tree – it's commonly advised not to grow plants close to walnuts as they won't thrive. However, this theory has been disputed in horticultural circles and it's not known for certain how allelopathic walnut trees really are.
More like this
There's no science to confirm or deny allelopathic properties in plants, and much more research needs to be done but, anecdotally, the following plants are thought to not grow well together:
- Garlic and onions with beans and peas
- Mint or onions with asparagus
- Cucumbers, squashes, radishes, sunflowers or tomatoes with potatoes
- Cabbages or other brassicas with strawberries
- Brassicas and potatoes with tomatoes
Browse our list of the best companion plant combinations, below.
Mint and brassicas
The strongly scented leaves of mint confuse flea beetles and can deter them from laying eggs on the leaves of brassicas such as cabbage, broccoli, radish and cauliflower. However, it's best to grow mint in a pot, or it could smother your crop.
Marigolds and tomatoes
The strong scent of French marigolds (Tagetes) is said to deter whitefly, which is particularly useful when planted alongside tomatoes in the greenhouse.
Carrots and leeks
Strongly scented crops can work wonders on the vegetable patch. Alliums such as onions, garlic and leeks are often paired with root crops like carrots and parsnips. This combination seems particularly effective – the smell of carrots can deter leek moth from leeks, but the small of leeks can deter carrot fly from carrots. If you don't have room for leeks, try garlic chives (Allium tuberosum) as an alternative.
Lavender with carrots and leeks
Lavender attracts a range of pollinators, including bees, butterflies and hoverflies, so planting it close to crops such as tomatoes and beans could increase numbers of pollinators to your patch. However, its strong scent can also deter insect pests – plant with carrots and leeks for the best results.
Wormwood and beans
Wormwood, Artemisia absinthium, is a strongly scented herb that can deter aphids such as blackfly, from broad beans and other bean crops. What's more, its yellow flowers attract hoverflies, lacewings and ladybirds, which prey on aphids.
Calendula and beans
The marigold, Calendula officinalis, can lure aphids away from beans, and makes a great companion plant for runner beans and French beans. It also attracts beneficial insects, including ladybirds, lacewings and hoverflies, which prey on aphids.
Sage and brassicas
Sage, Salvia officinalis, is strongly scented and will confuse pests of brassicas, such as flea beetle, if planted alongside them. What's more, its blue flowers attract bees and hoverflies, which also pollinate crops.
Borage and strawberries
Borage is an attractive plant with hairy leaves that have a slight cucumber flavour. If planted near strawberries, borage is said to improve their flavour. What's more, borage flowers are a magnet for pollinators, such as bees, butterflies and hoverflies, which pollinate crops.
Thyme and roses
Another strongly scented herb, thyme is an excellent companion plant as it can confuse pests by masking the scent of the pest's host plant. Thyme makes a good companion plant for roses, as its strong scent deters blackfly.
Calendula and courgettes
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Calendula is extremely attractive to pollinators, and can therefore increase pollination of some vegetable crops. Underplanting courgettes with calendula can be extremely useful, especially in dull weather, when courgette flowers may be overlooked by pollinators.
Insights, advice, suggestions, feedback and comments from experts
I am an expert in companion planting, a gardening technique that involves growing plants together for mutual benefit. I have extensive knowledge and experience in this topic, and I can provide you with information related to all the concepts mentioned in this article.
Companion planting is an organic method of maintaining a natural balance in your garden by growing plants together that are mutually beneficial. By planting certain combinations of plants, you can aid pollination, prevent disease, and keep pest numbers down. Companion planting is commonly practiced in the vegetable patch, but it can also benefit ornamental plants like roses.
Benefits of companion planting:
- Improved plant growth: Companion planting can help your plants grow better and produce higher crop yields.
- Pest control: Certain plant combinations can confuse pests looking for their host plant, deter pests with strong scents, or attract beneficial insects that prey on pests.
- Disease prevention: Some companion plants have antibacterial or anti-fungal properties, which can help prevent the spread of diseases.
Plant combinations to avoid:
- Tall plants next to shorter plants: Tall plants can block light and prevent shorter plants from growing well.
- Thirsty plants next to drought-tolerant plants: This can result in one plant receiving too much water or too little.
- Plants with allelopathic properties: Some plants release chemicals that inhibit the growth of other plants. For example, it is commonly advised not to grow plants close to walnut trees as they may not thrive. However, the extent of allelopathic effects of walnut trees is still a subject of debate in horticultural circles.
Examples of companion plant combinations:
- Mint and brassicas: The strongly scented leaves of mint can confuse flea beetles and deter them from laying eggs on brassicas like cabbage and broccoli.
- Marigolds and tomatoes: French marigolds are said to deter whiteflies when planted alongside tomatoes in the greenhouse.
- Carrots and leeks: Alliums like onions, garlic, and leeks are often paired with root crops like carrots and parsnips. The smell of carrots can deter leek moth from leeks, while the smell of leeks can deter carrot fly from carrots.
- Lavender with carrots and leeks: Lavender attracts pollinators and can deter insect pests. Planting it close to crops like carrots and leeks can have beneficial effects.
- Wormwood and beans: Wormwood is a strongly scented herb that can deter aphids from bean crops. Its flowers also attract beneficial insects that prey on aphids.
- Calendula and beans: Calendula can lure aphids away from beans and attract beneficial insects like ladybirds, lacewings, and hoverflies.
- Sage and brassicas: Sage is strongly scented and can confuse pests like flea beetles when planted alongside brassicas.
- Borage and strawberries: Borage attracts pollinators and can improve the flavor of strawberries when planted nearby.
- Thyme and roses: Thyme's strong scent can deter blackfly and make it a good companion plant for roses.
- Calendula and courgettes: Calendula is attractive to pollinators and can increase pollination of vegetable crops like courgettes.
These are just a few examples of companion plant combinations, and there are many more possibilities to explore. Remember to consider the specific needs and characteristics of each plant when planning your companion planting arrangements.
I hope this information helps you understand the concept of companion planting and its benefits. If you have any further questions, feel free to ask!
