Ladybird and hoverflies feed on pests - attract beneficial insects by practicing companion planting

Companion Planting - Grow Plants That Look Out For Each Other!

Once you’ve experienced the power of companion planting in creating a garden that looks after itself you won’t go back. It's a practice steeped in tradition yet as relevant as ever for the eco-conscious world. Let me take you through how companion planting is a major win for my gardening approach and leads to a more robust ecosystem.

The Role of Companion Planting

Companion planting is about understanding the mutually beneficial  relationships between different plants. This method lets me reduce pest problems naturally, improve pollination in the garden, and enhance soil nutrients without resorting to harmful chemicals.

The Science

Companion planting is deeply rooted in ecological science. It understands that plants can have beneficial or detrimental effects on their neighbours. For instance, some plants, like marigolds, emit natural chemicals that deter nematodes and other pests, while others, like leguminous peas such as sweet peas or other beans, fix nitrogen in the soil, benefiting their neighbouring tomatoes and future companions and crops you sow later in that soil. Trap cropping with plants like nasturtiums draws pests away from more valuable crops. My garden is a living laboratory where I've seen these interactions play out, reinforcing the science with every season.


Grow sweet peas to fix nitrogen in the soil for future crops


Companion plants tend to have a faint effect individually in the garden, but one that builds over time and comes into its own during adverse conditions.

Examples of Sacrificial and Beneficial Companions:

Monarda 'Beauty of Cobham' (bergamot) discourages flea beetles
  • Basil: The basil plant repels flies and mosquitoes and supports tomatoes
  • Onions: The strong scent of onions deters carrot flies from attacking carrot crops.
  • Alliums (plus chives, onion and garlic which all belong to the same plant family) discourage aphids (and garlic repels spider mites)
  • Nasturtium and nettles are a good choice, as they attract aphids, thrips, cabbage loopers, and other sap-sucking insects so they stay away from your crops. It is said to deter squash bugs and squash vine borers but I have never grown a single squash plant so can't vouch for it! Nettles (including stingless dead nettles) are a good plant  excellent breeding ground for butterflies.
  • Sunflowers are great for attracting stink bugs.
  • Chervil is a good sacrificial plant for attracting carrot flies and it repels slugs.
  • Hostas: Every gardener knows that slugs love the hosta plant - grow some from seed and they'll be unassuming and cheap, but the slugs will congregate on these. If you're protecting other hostas, make those less attractive. Try raising your favoured hostas !in pots with sandpaper banded around them or surround them with dried bramble stalks.
  • Chinese Cabbage is also a slug magnet - let them congregate then remove like an avenging hammer to stp them destroying your lettuce crops.
  • Artemisia Absinthium (wormwood) stops everything in it's tracks from slugs to cats, though its flowers do attract bees and hoverflies. It is very toxic and exudes chemicals which can slow the growth of members of the Apiaceae family - so carrots, celery and fennel crops are not good neighbours (and nether are kids or pets) - be careful where you put it.
  • Dahlias repel nematodes - and I don't even need an excuse to grow these beauties!
  • Monarda didyma (Bergamot) discourages flea beetles.
  • Marigolds (calendula) repel nematodes, whiteflies, and thrips.
  • Nepeta (catnip) repels aphids, ants, weevils, a number of unwelcome beetles, and fleas
  • Rosemary and Lavender also have a strong scent that confuses many pests, while also attracting bees and butterflies.
  • Sweet Peas: Sweet peas and Everlasting peas and all leguminous beans absorb nitrogen from the air and then fix it into the soil for other plants to use.


Photo of Calendula 'Pink Surprise'  (marigold) that can be grown as a companion plant to repel pests

Why Grow Companion Plants?

Companion plants offers a multitude of benefits. It reduces the need for chemical pesticides and fertilisers, promoting a more organic approach. This method also maximises space efficiency, allowing for more diverse plant species and contributes to a balanced ecosystem, attracting predatory beneficial insects and improving soil health. Also, a pottager garden with a tomatoes, flowers, fruit vines and trees all mixed together looks gorgeous...

Photo of a beneficial insect - a hoverfly feeding on Achillea millifolium 'summer pastels'

Tips for using sacrificials

Plant large clumps of your host plant to make them more attractive to pests.

Plant them around the edges of your garden to create a barrier to waylay pests from entering your main flowerbeds..

Interplant your sacrificial plants within your borders to confuse your unwanted guests and make it more difficult for them to find your favoured plants.

The greater variety of sacrificial plants grown, the greater the effect as a wider range of species will be attracted to them. It is important to site them close to your protected plants, but not so close that they touch! Just inspect your sacrificial plants regularly and remove any pests that you find, or better yet grow more plants that attract beneficial insect predators.

Which companion plants attract beneficial predator insects?

The best way to get rid of your unwanted visitors is to encourage their natural predators by growing plants that they appreciate for their nectar:

Limnanthes Douglasii - the poached egg plant - a lovely yellow and white annual, will fill your garden with hoverflies and bees. The hoverflies' larvae will decimate your aphid population in appreciation.


Limnanthes douglasii - the poached egg plant, grown as it is very attractive to hoverflies which is a major predator of aphids

Alyssum, aubrieta, geraniums, goldenrod, heliotrope, honesty, marigolds, Michaelmas daisies, nemophila, nicotiana, petunia, phlox, poppies, sedum spectabile, shasta daisies, sweet williams and wallflowers are also all great for attracting hoverflies.


Papaver 'Harvest Moon' grown to attract hoverflies to my your garden

Ladybirds and their larvae, lacewings and predatory wasps will also take their toll on aphid populations (though not nearly as well as the hoverfly) and will naturally congregate around your garden for as long as aphids are present.


Lady bird larvae feeding on aphids - ladybrids can be encouraged to your garden with flowering plants

How to Implement in Your Garden or Polytunnel

To start with companion planting:

  1. Assess Your Garden's Needs: Consider the pests common in your area and the soil's condition. Remember that different pests such as glasshouse mites affect polytunnels and greenhouses compared to your outside vegetables
  2. Choose Compatible Plants: Research which plants benefit each other and would be suitable for your style of gardening
  3. Plan Your Garden Layout: Arrange the chosen plants close enough to support each other but with enough space to grow.
  4. Plant in Groups. If you are growing a species of plant to attract or repel pests from your crops grow them in groups to magnify their effect.
  5. Intersperse your groups of plants around your garden or greenhouse vegetables - this will break up your crops, reducing vulnerable monocrop gardening habits that can fall prey all at once to a voracious predator.
  6. Use repellent plants on the outskirts of your garden to try and deter pests from flying in and sucking the life from your tomatoes. Can't beat a lavender hedge!
A lavender hedge - grow lavendula on the boundary of your garden to repel pest species

Protect Specific Species with These Companion Plant Pairings (plus sow more beans!)

Many plants pair well together, and all plants benefit from having leguminous peas and beans like sweet peas being grown to fix nitrogen in the soil.

  • Tomatoes: Grow Basil with plants to improve their health and flavour. Basil also traps aphids. Check carefully before you make pesto! Add some mozzarella for a nice salad all together! Maybe even some oregano...
  • Marigolds and Melons: Plant Marigolds to repel beetles and nematodes that could harm the melons.
  • Beans and Corn: Grow beans and peas to fix nitrogen in the soil, which is beneficial for corn and other hungry plants like tomatoes.
  • Onions and Carrots: These crops confuse each other's pests with their scent.
  • Squash: Grow nasturtum as a companion plant to deter many squash pests like aphids, whitefly and squash bugs and squash vine borers
  • Hosta with  wormwood: When fully grown Artemisia Absinthium deters slugs and snails
Artemisa Absinthium can be grown near hostas to discourage slugs

Which Plants to Sow to Fight Specific Pests:

These flowers and herbs will fight common garden and crop pests. Inter plant groups of each companion plant amongst your vegetable row seeds to increase their effect in your gardens veg patch or allotment

See this article For a FULL LIST of pests and the plants that deal with them

  1. Aphids:: Nasturtiums, marigolds, chives, and dill.

  2. Ants: Tansy, mint, and garlic.

  3. Cabbage Worms: Nasturtiums, dill, and celery.

  4. Carrot Fly: Rosemary, sage, and onions.

  5. Cucumber Beetles: Radishes, nasturtiums, and tansy.

  6. Flea Beetles: Catnip, basil, and marigolds.

  7. Japanese Beetles: Tansy, garlic, and rue.

  8. Moths (general): Nasturtiums, marigolds, and basil.

  9. Slugs and Snails: Rosemary, thyme, sage, wormwood and garlic.

  10. Squash Bugs: Radishes, nasturtiums, and tansy.

  11. Squash Vine Borers: Radishes, nasturtiums, and marigolds.

  12. Spider Mites:  Dill, cilantro, and chives.

  13. Thrips: Calendula, dill, and yarrow.

  14. Tomato Hornworms: Borage, marigolds, and basil.

  15. Whiteflies: Nasturtiums, marigolds, and basil.


Salvia hotlips, a cultivar of sage - repels carrot flies and mulloscs.

Advanced Tips and Techniques for those looking to deepen their companion planting practice:

Understand Allelopathy: 

Some plants release biochemicals that can inhibit or stimulate the growth of other plants: Artemisia Absinthium (wormwood) repels everything from slugs to cats, though its flowers do attract bees and hoverflies. It is very toxic and exudes chemicals which can slow the growth of members of the Apiaceae family - so carrots, celery and fennel are not good neighbours (and neither are kids or pets) - be careful where you put it.


Cut wormwood which can be placed to deter slugs, aphids and cats

Maximising Benefits with Integrated Pest Management

Companion planting is most effective when part of an Integrated Pest Management (IPM) strategy. This approach combines various organic methods to prevent, monitor, and control pests. In my garden nursery, IPM means encouraging beneficial insects, using natural repellents, and practising good garden hygiene alongside companion planting.

Grow a Sustainable Future with Companion Planting

Companion planting has been a cornerstone of my sustainable gardening practice. It's a testament to working with nature to create a healthy, productive garden. As we become more aware of our ecological impact, methods like companion planting are not just beneficial; they're necessary. So, whether you're a seasoned gardener or just starting, consider the power of companionship in your garden, from the soil to the insects – your plants (and the plant) will thank you!

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