Companion planting is the practice of growing plants together to support one another as part of a thriving garden community, to avoid pests, diseases and for plants to help support each other. Companion planting is the practice of growing certain plants together in close proximity because they benefit each other in some way.
Companion planting creates plant partnerships that help each other grow stronger, healthier, and more productive. Whether you're growing vegetables on your allotment or designing a stunning flower beds, it's a means of using plants together to reduce the overall effort we need to input to keep our gardens looking their best and being productive.
Anyone who knows me knows that Garden Ninja loves a good gardening technique that makes your life easier while creating better results! After 35 years of hands-on gardening experience and working on BBC Garden Rescue, I can tell you that companion planting is one of those brilliant traditional practices that modern science has proven actually works. Let me show you exactly how to use this game-changing technique in your own garden.
Fear not if you're thinking this sounds complicated, companion planting is actually quite straightforward once you understand the basic principles. Companion planting works through several natural mechanisms that plants have evolved over millions of years to help each other survive and thrive.
Many plants naturally produce compounds that repel specific insects or mask the scent of neighbouring plants that pests are searching for. For example, the strong aroma of basil confuses thrips and flies that would otherwise attack your tomatoes. It's like having a natural security system in your garden!
Certain flowering plants act as magnets for predatory insects, parasitic wasps, and pollinators that help control pest populations and improve fruit set. When you plant marigolds near your vegetables, you're essentially rolling out the red carpet for ladybirds and other garden helpers.
Different plants have varying root depths and nutritional needs, so they can actually complement each other below ground. The classic example is how beans and peas fix nitrogen from the air into the soil, enriching it for heavy feeders like brassicas planted nearby.
Companion planting allows you to use vertical space more efficiently and create beneficial microclimates. Tall plants can provide shade for heat-sensitive crops, while ground-covering plants suppress weeds and retain soil moisture.
Let me share some tried-and-tested combinations that I've used successfully in my own garden and recommended to clients during my BBC Garden Rescue transformations.
The Three Sisters combination of corn, beans, and squash is perhaps the most famous example of companion planting, and for good reason. This ancient Native American technique demonstrates perfect plant cooperation:
The thing is, this combination works because each plant fills a different niche. The corn reaches for the sky, the beans climb upward while enriching the soil, and the squash spreads across the ground. It's like a perfectly orchestrated garden symphony!
Tomatoes and basil make excellent companions for both practical and culinary reasons. Basil naturally repels thrips, flies, and the moths that lay tomato hornworms. Even better, many gardeners swear that basil actually improves the flavour of tomatoes when grown nearby.
Marigolds planted around tomatoes provide a double benefit. French marigolds produce limonene, which repels whiteflies, while their strong scent confuses aphids and other pests. I always tell my Garden Ninja course students to think of marigolds as the garden's natural pest control officers!
Carrots and tomatoes work well together because carrots help break up the soil around tomato roots, and tomatoes provide some shade for the carrots during hot summer days. Just make sure to give both plants adequate space to develop properly.
Alliums (onions, garlic, leeks, chives) are fantastic companions for almost everything except beans and peas. Their strong sulphur compounds repel aphids, carrot flies, and many other pests. I particularly love planting chives around roses – they help prevent black spot while adding lovely purple flowers.
Nasturtiums act as the perfect trap crop, attracting aphids away from your precious beans and brassicas. They're essentially sacrificial plants that lure pests to themselves rather than your main crops. Plus, their peppery flowers are completely edible – a bonus for the kitchen!
Dill and fennel attract beneficial insects like ladybirds and parasitic wasps, but keep them away from carrots and tomatoes as they can stunt their growth. The key is understanding which plants play well together and which prefer their own space.
Don't think companion planting is just for vegetable gardens! I use these principles extensively in my ornamental garden designs, and they work beautifully for creating stunning, healthy flower beds.
Roses and geraniums make a classic pairing that's both beautiful and practical. Geraniums help deter Japanese beetles and aphids from roses while adding continuous colour throughout the growing season. The cultural requirements are similar – both thrive in well-drained soil and full sun.
Lavender planted near roses provides natural pest deterrence while creating a gorgeous colour and fragrance combination. The silver-grey foliage of lavender provides excellent contrast to rose foliage, and both plants benefit from similar growing conditions.
Catmint (Nepeta) around roses is another winning combination. It deters aphids and attracts beneficial insects while providing a soft, cloud-like backdrop for rose blooms. The long flowering period of catmint extends the garden's appeal beyond the main rose season.
Coneflowers (Echinacea) and black-eyed Susans create stunning summer displays while supporting each other's growth. Both are drought-tolerant once established and provide excellent nectar sources for beneficial insects. Their seed heads also provide winter interest and food for birds.
Astilbe and hostas demonstrate perfect shade garden companionship. Astilbe's feathery flowers provide brightness in shaded areas, while hostas offer bold foliage texture. Both plants prefer similar moisture levels and soil conditions.
Ornamental grasses paired with late-season perennials like asters and sedum create movement and structure while extending the garden's interest into autumn. The grasses provide support for floppy perennials while adding textural contrast.
Let me break down why companion planting should be part of every gardener's toolkit, whether you're growing vegetables or ornamentals.
Companion planting reduces pest pressure by creating a more diverse environment that supports natural predators. Instead of reaching for pesticides, you're working with nature's own pest control system. Plants like yarrow, dill, and calendula attract tiny parasitic wasps that control aphids and other soft-bodied pests.
The principle of olfactory confusion means that aromatic plants mask the scent of target crops, making it harder for pests to locate their preferred food sources. This is why planting sage near brassicas helps confuse cabbage moths, and why rosemary planted near beans deters bean beetles.
Nitrogen fixation from legumes is one of the most significant benefits of companion planting. Every time you plant beans, peas, or clover, you're essentially adding a natural fertiliser factory to your garden. The bacteria in root nodules convert atmospheric nitrogen into plant-available forms.
Different root depths reduce competition while maximising nutrient uptake. Deep-rooted plants like burdock and comfrey bring up minerals from lower soil layers, while shallow-rooted plants utilise nutrients in the topsoil. This creates a more efficient use of available resources.
Vertical growing systems maximise production in limited space. Training beans up corn stalks, growing lettuce in the shade of taller plants, or using quick-growing radishes as living mulch all help you get more from your garden area.
Succession planting with companions means you can extend harvests and maintain continuous garden interest. Plant quick-growing crops like lettuce between slower-developing plants, or use early bulbs followed by summer perennials in ornamental beds.
The key to successful companion planting is starting simple and building your knowledge through observation and experience. Here's how to begin your companion planting journey:
Start with your main crops or focal plants and then select appropriate companions. In vegetable gardens, this might be tomatoes, peppers, or brassicas. In ornamental gardens, consider your structural plants like roses or larger perennials as your anchors.
Consider mature plant sizes when planning spacing. A common mistake is planting companions too close together, which creates competition rather than cooperation. Most companion plants should be within 2-3 rows of each other for maximum benefit.
Think about timing and succession. Plant quick-growing companions like radishes or lettuce between slower-developing plants. This maximises space use and provides continuous harvests.
Research compatibility carefully before committing to large plantings. While many combinations work well together, some plants actively inhibit each other's growth. For example, fennel and most vegetables don't play well together, and black walnut trees produce compounds toxic to many plants.
Start with proven combinations like the Three Sisters, tomatoes with basil, or roses with lavender. These partnerships have been tested by generations of gardeners and consistently deliver results.
Consider your local conditions when selecting companions. Plants that work well together in one climate or soil type might not be suitable for your specific garden conditions.
Even experienced gardeners can make errors when implementing companion planting. Here are the pitfalls I see most often:
This is the biggest mistake I encounter. Enthusiasm for companion planting can lead to cramming too many plants into small spaces, which creates competition rather than cooperation. Always respect mature plant sizes and spacing requirements.
Can create problems. Planting related crops together, like tomatoes and potatoes, can actually increase pest and disease pressure since they share similar vulnerabilities.
While beneficial, companion planting works best as part of a comprehensive garden management strategy that includes proper soil preparation, adequate watering, and good garden hygiene.
If you're finding companion planting as fascinating as I do, you might be interested in learning more about creating stunning garden designs that incorporate these principles. Did you know that you can take my Garden Design for Beginners course and learn how to become a Garden Ninja yourself?
My comprehensive online course covers everything from basic design principles to advanced planting combinations, including detailed modules on companion planting for both productive and ornamental gardens. At £199, it's a fraction of the cost of traditional garden design courses, and you'll learn from an award-winning designer and BBC Garden Rescue presenter.
Garden Design Examples for Small Gardens: 30 Design Templates & Planting Plans: In this online gardening course, I'll walk you through 30 fantastic garden designs, explaining the logic behind the layout, the plant choices, and take-home tips for applying them in your own garden.
Learn how to transform and design your own garden with Lee Burkhills crash course in garden design. Over 5 hours Lee will teach you how to design your own dream garden. Featuring practical design examples, planting ideas and video guides. Learn how to design your garden in one weekend!
Garden Design for Beginners Online Course: If you want to make the career jump to becoming a garden designer or to learn how to design your own garden, this is the beginner course for you. Join me, Lee Burkhill, an award-winning garden designer, as I train you in the art of beautiful garden design.
The course includes 20 hours of video lessons, practical assignments, and access to our active Garden Ninja community where you can share your successes and get advice on challenging situations. You'll learn the same design principles I use on BBC Garden Rescue, but at your own pace and with lifetime access to all materials.
Whether you want to design your own dream garden or even start a career in garden design, the course provides all the tools and knowledge you need to create beautiful, functional outdoor spaces that work with nature rather than against it.
Companion planting represents one of gardening's most elegant solutions – using natural plant relationships to create healthier, more productive gardens. By understanding how different plants support each other through pest deterrence, soil improvement, and space optimisation, you can create thriving garden ecosystems that require less intervention and provide better results.
The beauty of companion planting lies in its accessibility. Whether you're growing vegetables in containers on a balcony or designing extensive ornamental borders, these principles can be adapted to any scale or style of gardening. Start with simple, proven combinations like tomatoes and basil or roses and lavender, then expand your knowledge through observation and experimentation.
Remember, successful companion planting isn't about following rigid rules – it's about understanding plant relationships and adapting them to your specific garden conditions. Each garden is unique, and what works brilliantly in one situation might need adjustment in another.
The key is to start small, keep good records of what works in your garden, and don't be afraid to experiment with new combinations. With time and observation, you'll develop an intuitive understanding of which plants work well together and how to create harmonious garden communities that thrive with minimal intervention.
Happy gardening, and here's to creating beautiful, productive gardens through the power of plant partnerships!
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