A Guide to Companion Planting
Do you want better harvests from your garden without resorting to strong chemicals or mountains of plastic netting?
One way to protect plants from attack by insects and gastropods is to grow companion plants close by. These flowers, herbs and veg plants distract, repel or sometimes act as a sacrificial barrier between pests and your favourite crops.
They also look great, helping you create an attractive veg garden that’s a haven for helpful pollinators. Here are the basics of companion planting.
What is companion planting?
Think of the Native American “three sisters” system of planting corn, beans and squash together. The corn shoots up to provide beans with a stem to climb; the squash foliage acts as mulch, locking in moisture and keeping weeds at bay; and the beans fix nitrogen into the soil, which helps the other plants grow.
Any combination of plants in which one plant benefits another is known as companion planting – it’s a science humans have practised since we first learned to cultivate crops. You can put it to good use in your garden to help you grow more bountiful crops while minimising your use of pesticides. Best of all, pollinators love it when you garden this way.
Why does companion planting work?
It’s no wonder that growing different plants side by side often benefits both – after all, that’s the way they grow in nature. Some plants, like mint, produce a strong aroma that deters pests like flea beetles. Others provide shade – lettuce grows well under brassicas. And other plants act as a sacrificial barrier, tempting insects away from other more valuable crops – bolted lettuces provide a tasty snack for slugs and snails, keeping them away from your prize cabbages.
There are many different combinations of plants that grow well together but here’s a selection to get you started.
1. Companion plants that ward off predators
Try planting tomatoes along with your asparagus. This is a great partnership because tomato plants exude a chemical that the voracious asparagus beetle doesn’t like. Plant these companions at the same time so that the tomato doesn’t cast too much shade over the young asparagus plants.
Add a third plant to create a symbiotic crowd – basil goes well with tomatoes because the same strong aroma which makes our taste buds water keeps tomato-loving pests away – a win, win for gardeners. If you love filling your greenhouse with tomatoes, the good news is that basil will enjoy the warmth in there too.
Do your roses fall victim to blackfly? Plant thyme alongside – these pesky attackers hate the smell. Problem with whitefly attacking your cabbages? Soak thyme leaves in water and use the “tea” as a spray.
2. Companion plants that attract pollinators
Sage is a great companion plant to grow along with brassicas – the powerful aroma repels pests while the pretty blue flowers attract bees and hoverflies. Plus of course sage is a wonderful herb that goes particularly well with pork or chicken, or mixed with a little melted butter and drizzled onto gnocchi or fresh pasta.
Bright, colourful and nutritious, calendula flowers also deter a variety of pests. Plant calendula alongside beans to distract aphids and among your tomatoes to deter whitefly. As well as protecting your crops, calendula are brilliant at attracting friendly pollinators and species that prey on aphids.
Helpful garden insects like hover flies, lacewings and ladybirds find the bright, vibrant colour of marigolds irresistible, laying their eggs close by. Their hatching larvae love to feast on aphids, keeping the numbers of these harmful pests right down.
Borage is a feisty plant which, as well as being a vital ingredient of a decent Pimm’s, attracts a wide range of pollinators making it a great choice to sow in amongst your fruit bushes and trees. At the same time, borage also works well with brassicas, distracting cabbage white butterflies who, faced with a mass of blue flowers, will be put off laying their eggs on your broccoli and kale.
3. Companion plants that grow better together
Sunny garden setting? Grow your lettuce beneath the leafy shade of larger brassicas – that way you’ll get lusher leaves and the plants are less likely to bolt. Use the same concept to plant cucumbers in the shade of sunflowers or maize.
Different plants take nutrients from different parts of the soil. Carrots have long roots, so plant them along with radishes which will grow quite happily in the top layer of soil.
And don’t forget your sacrificial plantings. It’s far better to let aphids munch your marigolds than it is to let them infect your broad beans. It’s less soul-destroying to let insects devour your nasturtiums than attack your brassicas. That’s mother nature working for you to ensure you get bumper crops each year without resorting to the kind of chemicals that contribute to killing precious pollinators. Thoughtful gardening helps save the planet.
Want a quick recap on companion planting? Watch our short video guide now for some more helpful tips:
Lead image: fotoknips