By following companion planting, you can work with nature in your garden or allotment and not against nature. Points are awarded for companion planting in Allotments and Vegetable/Kitchen Gardens for the Guildford in Bloom awards as a way of encouraging biodiversity and organic gardening methods
It may take a bit more planning, but you will create a biodynamic and organic space without the need for chemicals. In short, it is an organic way of maintaining the natural balance of biodiversity in a garden or plot by growing plants close together for their mutual benefit.
There are certain combinations which have been proven to help pollination, keep pests down and prevent diseases.
Companion planting works in many ways; some have anti-fungal or antibacterial properties; some have a strong scent which can confuse pests looking for the main plant; and others attract insects such as ladybirds, which will prey on aphids.
Usually companion planting is found on allotments and vegetable plots but it can help flowers too – For example, growing chives close to roses can help resist blackspot.
The benefits are many – helping plants resist diseases and pests – without the need for chemicals – means less work for the gardener with higher yields.
Here are a few well known and helpful combinations.
Nasturtium will deter aphids from beans.
Alliums with Carrots will deter carrot root fly.
Grow mint alongside Brassicas such as cabbage, cauliflower and broccoli – the strong scented mint leaves will confuse flea beetles and prevent them from laying eggs on the brassica leaves. But it is better to keep your mint in a pot or it will completely take over, smothering the brassicas.
French marigolds are known to deter whitefly – so planting so near tomatoes – even in the greenhouse is a good idea.
Planting root crops such as carrots and parsnips with strongly scented crops such as onions, leeks and garlic is also effective. The fragrance of the carrots will keep leek moth away from the leeks, while the smell of leeks deters carrot fly from the carrots – garlic chives work well too if you are stuck for space.
Lavender is one of the best pollinator cafes attracting bees, hoverflies and butterflies – so planting lavender close to tomatoes and beans attracts more pollinators to your plants and its strong fragrance can deter pests.
If you are growing broad beans, or indeed any bean crop, Wormwood is extremely useful in deterring aphids such as blackfly. Also, the yellow Wormwood flowers attract ladybirds and hoverflies which also prey on aphids.
Marigold planted with runner beans and French beans also attracts pollinators and insects that will prey on aphids.
Sage is particularly useful when planted close to brassicas – its blue flowers attract pollinators, and the strong aroma confuses pests such as flea beetle.
Borage with its hairy leaves and flowers are a magnet for pollinators and it is believed that if planted with strawberries will improve their flavour.
Thyme is a particularly good companion for Roses with its strong fragrance deterring blackfly.
Calendula is a magnet for pollinators and can be underplanted with courgettes.
However – not all combinations are beneficial and some are better avoided. Tall plants will of course block light from short ones and stunt their growth. Thirsty plants adjacent to drought-resistant plants are also incompatible.
It is possible that some plants will release chemicals that inhibit the growth of others – there is little research into this so trial and error seems to prevail, but from anecdotal evidence the following combinations should be avoided.
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. When Guildford in Bloom judges visit allotments and vegetable gardens, they look for companion planting. You can read all the Judging Criteria here.
We would love to hear your stories of successes and failures of your companion planting experiments so we can all learn together.
To enter Guildford in Bloom 2023 – download the entry form from here; https://www.guildfordinbloom.com/2022-guildford-in-bloom-competition