In gardening, it has long been said that some plants like each other more, and others less. That’s exactly what companion planting is about – the art of growing vegetables, herbs, and flowers together in ways that help one another. They can protect against pests, improve flavour, make better use of space, or share nutrients more efficiently.
The problem is that there’s a lot of contradictory information out there. That’s why it’s worth focusing on what has actually been tested in practice and confirmed by horticultural research.
Vegetables and herbs that protect against pests:
- Basil + tomato – repels whiteflies and aphids.
- Garlic + roses and strawberries – protects against fungal diseases.
- Marigold + tomato and cucumber – reduces soil nematodes.
- Nasturtium + cabbage and kohlrabi – draws aphids away from vegetables.
- Tansy + fruit trees – repels ants and aphids.
Mutual growth benefits:
- Carrot + onion and leek – protect each other from carrot fly and onion fly.
- Beans + corn – beans fix nitrogen, corn provides support.
- Peas + carrots – peas add nitrogen, carrots grow better.
- Lettuce + radish – different growth speeds, better space usage.
- Spinach + strawberries – spinach creates a favorable microclimate.
Herbs that improve flavour and resilience:
- Dill + cucumber – improves flavour and growth of cucumbers.
- Mint + cabbage – repels cabbage white butterfly.
- Sage + carrot – protects against carrot fly.
- Thyme + aubergine – repels Colorado potato beetle.
Flowers that support vegetables:
- Tagetes (French marigold) + tomato – controls nematodes.
- Lavender + roses – repels aphids.
- Chamomile + cabbage – strengthens cabbage growth.
Growth suppression:
- Beans + garlic, onion, and chives – weaken each other’s growth.
- Cabbage + strawberries – mutually suppress growth.
- Potatoes + tomatoes – both vulnerable to blight.
- Cucumber + potatoes – potatoes stunt cucumber growth.
Competition for nutrients:
- Carrot + dill – compete for space and nutrients.
- Tomato + kohlrabi – kohlrabi weakens tomatoes.
- Celery + corn – strong nitrogen competition.
- Walnut tree + most plants – releases chemicals that block growth.
- Sunflower + potatoes and beans – allelopathic negative effect.
- Rue + basil – mutually suppress growth.
Other conflicts:
- Peas + garlic and onion – peas grow worse.
- Lettuce + parsley – poor neighbors.
- Spinach + potatoes – poor neighbors.
- Beetroot + beans – mutually inhibit growth.
Key principles in a nutshell:
- Avoid planting crops from the same botanical family side by side.
- Combine shallow-rooted and deep-rooted plants.
- Pair plants with different nutrient requirements.
- Tall plants can shelter shade-lovers but harm sun-lovers.
- Legumes improve soil for nitrogen-demanding vegetables.
Companion planting is like a fascinating gardening game – part strategy, part experience, and lots of observation. What works in one garden may not work as well in another. That’s why it’s best to treat these principles as a starting point and keep your own notes on how your vegetables grow in your particular conditions.