Guide to Companion Planting

Companion planting can bring a number of great benefits to the garden. For those who prefer to use the minimum or no plant protection products in their garden, companion planting can be a successful way to tackle a number of pests. Some plants act as natural deterrents, while others attract beneficial insects that are the natural predators of less wanted visitors. Companion plants can also add a touch of pretty colour to your vegetable patch or allotment.

The following plants offer a natural deterrent to some of the less desirable creatures that attack crops: 

  • Plant marigolds in your vegetable patch to deter whitefly and attract ladybirds, which will help to control aphids. They also emit a substance from the roots that deters damaging nematode worms in the soil. 
  • Plant nasturtiums alongside your brassicas to attract cabbage white butterflies away from your precious greens. They are also good near beans and peas, as aphids will be naturally drawn to the nasturtiums instead. Nasturtiums leaves and flowers have the added bonus of being a tasty and vibrant addition to your salads.
  • Plant pungent vegetables, such as onions, garlic or chives next to your carrots to deter carrot fly.
  • Plant aromatic herbs, such as rosemary, sage, dill and mint alongside broccoli or lettuces. Their scent will deter a number of common and unwanted insects that might otherwise eat them. Be cautious when planting mint - it can easily become invasive in a vegetable patch. Planting it in a pot and sinking the pot into the ground is a good way to keep it under control.
  • Borage is a fantastic companion plant. It can act as a repellent to tomato hornworn if planted near your tomato plants. It is also considered one of the best plants to position near strawberries, deterring many of the pests that would attack them - including by attracting the pollinators that naturally prey on these pests - as well as improving the flavour of the strawberries. 
  • Plant basil near to tomato plants and peppers. It will deter flies as well as increasing the yield.
  • Plants that are loved by bees, such as lavender and dahlias, can attract these wonderful pollinators that in turn will pollinate your tomatoes, cucumbers, aubergines, peppers, strawberries and more. Position near where you are growing your plants, or in a pot beside the greenhouse door. 

The value of companion planting goes beyond the helpful, natural pest deterrent properties of plants. As a form of polyculture (as opposed to monoculture), growing certain plant species together can bring benefits which are sometimes mutually experienced. Examples of this are:

  • Carrots and tomatoes. When grown in the same space, carrots aerate the soil, helping the tomato plant get more water to its roots. In return, the tomato plant will offer much-needed shade for your carrots as they grow. 
  • Sweetcorn needs a good supply of nitrogen in order to produce the best yield. Plant together with notorious nitrogen-fixing plants - in particular, peas and beans (any variety) - that are excellent at converting nitrogen in the air into nitrogen trapped in bacteria in the soil, helping your sweetcorn grow.