Companion planting is a time-tested gardening method in which gardeners grow different kinds of plants together to provide mutual benefits. It can reduce pests, attract beneficial insects, improve soil fertility, and increase crop yield. Here’s a simple guide to companion planting to help get you started.
What is Companion Planting?
Companion planting involves planting different varieties of plants, such as flowers or vegetables, nearby to aid pollination, keep pests at bay, prevent diseases, or promote healthy growth. Most companion plants are strongly scented, which either deters pests or attracts beneficial insects, such as ladybirds. Some companion plants also have anti-fungal properties. Understanding the right combinations can transform your garden into a thriving ecosystem.
Benefits of Companion Planting
Pest Control
One significant advantage of companion planting is natural pest control. Certain plants repel harmful insects with their strong scents or attract predator insects that feed on pests.
- Garlic and onions: Planted near crops such as carrots, the smell of garlic and onions can mask the scent of carrots and their foliage from carrot root fly.
- Nasturtium: This flower lures butterflies away from brassicas like kale, cabbage, and broccoli.
Attracting Beneficial Insects
Some plants attract insects that are beneficial to the garden. These insects can help with pollination or by preying on harmful pests.
- Borage: This plant attracts pollinating bees and, if planted near strawberries, is said to improve their flavour.
- Dill: Attracts ladybugs and parasitic wasps, which control pests like aphids and spider mites.
Soil Improvement
Certain plants improve soil fertility by fixing nitrogen or bringing up nutrients from deeper soil layers.
- Legumes: Beans and peas fix nitrogen in the soil, which benefits other plants such as brassicas.
- Deep-rooted plants: Plants like comfrey bring up nutrients from deep within the soil, enriching the topsoil for shallow-rooted plants.
Combinations to Avoid
Some plants are thought to have allelopathic properties, releasing chemicals that can inhibit the growth of other plants. This theory is widely debated and more research is needed. However, the following plants do not grow well together:
- Garlic and onions with beans
- Brassicas and strawberries
- Brassicas with potatoes and tomatoes
- Mint, onions, garlic, and leeks with asparagus
Popular Companions
Nasturtiums and Brassicas
Nasturtiums are excellent for attracting bees into your veg plot and will also attract cabbage white butterflies away from your brassica plants. As an added bonus, nasturtiums are also edible, including the leaves and the flowers, and are great in a salad.
Marigolds and Tomatoes
Marigolds are excellent companion plants for tomatoes. Their scent helps deter whitefly and tomato hornworms. French marigolds are also known to help combat root nematodes in the soil. They are also good at attracting hoverflies, bees, and butterflies.
Carrots and Onions
Aromatic companions like onions or leeks can mask the scent of carrots and their foliage from carrot root fly and moths. If you don’t have room for onions, you can try chives.
Borage and Strawberries
Planting borage next to or near strawberries supposedly improves the flavour of the strawberries. As an added bonus, borage flowers are excellent at attracting pollinators, such as bees, butterflies, and hoverflies, which can help pollinate your strawberries and other flowering crops.
Calendula and Courgettes
Calendula is an easy-to-grow flower that will keep flowering throughout the summer months. They will grow in any soil and love full sun. Calendula is excellent at repelling pests such as aphids and cabbage white butterflies and attracting pollinators. Planting calendula next to crops such as courgettes can help with pollination and increase yields.