Companion Planting: Natural Pest Control & Better Harvests
Companion planting is a method of gardening where different plant communities are grown together to share in their mutual benefits. In some cases, this means improving growth rate, flavour, or helping with pollination. In others, it’s more about employing methods of natural pest control by attracting certain insects, deterring others, or even sacrificing certain plants to protect vulnerable crops.
Research shows that monocultures, where one single plant variety is grown, are not good for plant health and increase the risk of pest issues. Whilst much of the evidence is anecdotal when it comes to the success of companion planting, it has been around for thousands of years in various cultures and can improve the success rates of your harvest.
How can companion planting help?
Some of the ways of including companion planting in your gardening include:
- Using taller plants to create partial shade for crops that are prone to bolting like spinach, coriander, and lettuce to help stop this from happening.
- Using strong smelling herbs throughout your garden and vegetable plot to help repel damaging insects.
- Intercropping by sowing fast-growing vegetables like lettuce and radish between widely spaced rows of slower growing crops like Brussels sprouts or parsnips. Not only does this use more of your available space, but it also prevents weed growth. You can also plant shallower rooted crops alongside deeper rooted crops so that they are not in competition for nutrients at the same soil level.
- Encouraging insects or birds that will prey on pests to protect your vegetables. Grow specific plants amongst your crops or nearby to encourage them into the garden. Many birds will eat slugs, whilst hoverflies and ladybirds will eat aphids. Attracting bees with this method is also a great way of pollinating your crops.
Companion Plants and How to Use Them
To give you some more ideas, here are some more specific plants and combinations that can elevate your vegetable patch this year.
Nasturtium
Whilst many know nasturtium to produce pretty, edible flowers, it makes an excellent companion plant.
You can use nasturtium as a sacrificial crop around your brassicas like cabbage, cauliflower, and broccoli to help protect against cabbage white butterflies.
They prefer to eat nasturtium leaves and will choose to lay their caterpillars here instead.
Nasturtium is also attractive to aphids and can draw them away from your vegetables, making it particularly good to plant around French Beans and Runner Beans. There are some reports that it may repel ants and whitefly too, whilst trailing varieties can create a protective blanket for your crops. This gives them more shade in the summer heat and can help the soil to maintain moisture.
Marigold
The strong smell of marigold flowers is said to deter whitefly, which makes it an excellent flower to plant alongside tomatoes.
Marigolds also release a chemical that reduces the reproduction of aphids, which is invaluable in any vegetable patch.
This year, we’ve introduced our new Marigold Gem Mix Seed Tape to make companion planting in your garden even easier.
Calendula
Not only is Calendula a beautiful flower, but it is irresistible to pollinators.
Planting these bright flowers near vegetables like courgettes can really help the pollination process and give you much greater success.
Calendula flowers are also said to lure away aphids whilst attracting beneficial insects that prey on them like hoverflies, ladybirds, and lacewings, making them an excellent companion for crops of beans.
Basil
Whilst basil is a versatile and rewarding herb to grow, it also makes for an excellent companion plant. The strong aroma can repel an array of common garden pests, whilst basil plants that are left to flower attract a wide variety of pollinators.
Many gardeners report that planting basil with tomatoes improves their flavour and the overall health of the plant.
It also makes an excellent companion for both sweet peppers and chillies, and can help deter asparagus beetles.
Carrots & Onions
This is a classic combination of crops to plant together for many reasons. Firstly, the shallow-rooted onions and the deep-rooted carrots don’t compete for nutrients in the soil, meaning they can grow well together. In addition, the smell of the onion is said to confuse carrot fly, whilst the smell of the carrots confuses onion fly, making them natural pest control partners.
This also works with carrots and leeks as the carrot smell deters leek moths and the leek smell deters carrot fly. Members of the allium family like onions, leeks, garlic, and chives are all strong-smelling plants that can help repel a variety of would-be pests.
The 3 Sisters Method
If you wanted to try something different this year, why not look at the well-documented 3 Sisters method from North America? The indigenous people would combine maize or corn, climbing beans, and squash together as they are all mutually beneficial.
The sweetcorn provides a tall frame for the beans to climb up, and the beans provide strength and stability against the wind in turn. Beans are also excellent at fixing nitrogen in the soil, which promotes better growth in the other plants. The squash grows in the space between with their large leaves helping to keep the ground moist and preventing the growth of unwanted weeds.
You can use other compact bushy varieties of cucurbits like pumpkins or courgettes. Some of these also have spiny leaves, which can stop grazers like deer or squirrels from eating your crops.
