Companion Planting for Increased Garden Success!

Whether you are a new gardener or have a few growing seasons under your belt- companion planting is a great way to boost your garden’s overall success. Companion planting can decrease pest, disease, and weed pressure on your crops, can help with water retention, and can lead to higher yields & tastier fruits/ veggies!  

Tomatoes intercropped with a variety of flowers from Burnhamthorpe Collegiate's School Grown program, Toronto.   

First off, let’s talk about what companion planting is. In Richard Bird’s book, “Companion Planting,” he reminds us that companion planting is nothing new. Many early societies all over the world had this practice, and you can still find their descendants using these techniques today, thousands of years later. Bird says that companion planting’s aim is “simply to provide the best environment for growing vegetables and flowers by selecting the correct plants as neighbours” (p. 5, 1996).  

A well-known example of companion planting is the 3 Sisters practice, originating from Indigenous Peoples on Turtle Island. The practice of planting squash, corn, and beans together spread across Turtle Island from its southern area or “Mesoamerica,” to its more Northern regions, being adopted by the Haudenosaunee and then other Nations. The 3 Sisters support and benefit each other. Corn, growing in the centre, provides support to the climbing beans that need to find their way to the sky. The beans fix Nitrogen into the soil, and help feed the other 2 sisters. Squash provides shade and therefore moisture to the roots systems of the beans and corn, and squash’s prickly nature can also deter pests who may otherwise be interested in munching on tender beans and corn. I have witnessed these crops growing separately and together, in the same garden in the same season, and those planted together are noticeably more productive and they just look happier!

 

A distant 3 Sisters Mound and clump of beautiful bergamot at Twin Forks Community Garden in Sudbury, Ontario.

Let’s focus some energy on pest pressure now because I am sure you have had cabbages, kale, and broccoli in your garden (all members of the brassica family) full of holes before, and maybe you have had aphids attack your tomatoes, or cucumber beetles scar your cucumbers, zucchinis, or squash (cucurbit family). Maybe you have had earwigs and cutworms decimate your seedlings before they even had a chance to grow more than a few true leaves, or have had leek moths munch on your garlic and onions. The solution to this pest pressure problem (or one of them at least), is, as my wise, farmer friend Isabelle Spence-Legault of Fieldgood Farms in Cache Bay, Ontario once said, a “Wall of Flowers!” But not just any flowers. We are talking about flowers and plants that attract beneficial insects (i.e. parasitoid wasps, lacewings, hoverflies, ladybugs, etc.) that predate on the less desirable ones and flowers and plants that repel pests on their own due to their smell and/or taste.

 

Kale intercropped with various other flowers and veggies at Burnamthorpe Collegiate in Toronto (Foodshare's School Grown Program site).

Plants that create little landing pads for insects are very popular with the ones we want to attract, and plants that have “umbels” (they do look like little umbrellas, and are referred to as umbellifers) are the ones you want. These include, Cilantro/Coriander, Dill, Fennel, Carrots & Parsnips (which are biennials, meaning you will have to wait until their 2nd season in the ground for them to go to seed). Other examples include Parsley, Celery, Cumin and Anise. With these plants you need to let them go to flower/seed- no harvesting prior, or else their insect “landing pads” will not form (but then you can save their seeds). Some of these plants repel insects on their own, prior to flowering, i.e. cilantro repels aphids, potato beetles, and spider mites. Parsley repels asparagus beetle.

More examples include:

  • Yarrow, which is awesome because it repels aphids, but attracts hoverflies, ladybugs, and parasitoid wasps that prey on garden grubs. 
  • Licorice Mint aka Anise hyssop (Agastache), which is attractive to bees and lures cabbage moths away from brassicas (so plant them further away from the garden).
  • Borage, deters tomato hornworms and cabbage moth larva and is loved by pollinators (so plant it near all of your crops that rely on insects for fruit/veggie production).
  • Calendula repels problematic soil nematodes and asparagus beetles, and attracts pollinators (and flowers all season long).
  • Coreopsis attracts pollinators, and other beneficials like hoverflies, soldier bugs, and tachinid flies.
  • Echinacea attract hoverflies and parasitoid wasps.
  • Bee Balm/ Bergamot attracts pollinators, parasitoid wasps, tachinid flies, and hummingbirds.
  • Rudbeckia attract hoverflies and parasitoid wasps.
  • White flowering Chrysanthemums or Mums repel Japanese beetles and attract tachinid flies and parasitoid wasps.  

We also need to remember that just like in the human world, some neighbours are better to us than others. There is some caution to be taken in the garden when it comes to planting certain crops with others. This is a vast area to cover, and you will need to do your own research, but here are some examples of plants NOT to grow near one another:

  • Beans (pole, green) do not do well with chives, garlic, leeks, or onions (i.e. allium family). Pole beans and beets are said to stunt each other’s growth.
  • Carrots should not be planted near dill, parsnips, or potatoes. Carrots planted near tomatoes may have stunted roots (but will have awesome flavour).
    • Cucumbers should not be planted near to potatoes or sage.

    • Corn should not be planted near celery or tomatoes.

    • Fennel is by far the worst companion, and should be planted on its own, or bordering the garden with enough space between it and other crops. It does attract plenty of the good guys, and it is amazing roasted or in salads, but it will inhibit the growth of other plants. Have you heard of allelopathy? It is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms.

    • Garlic should not be planted near beans or peas of any kind.

    • Potatoes should not be planted near to asparagus, the brassica family, carrots, cucumber, melons, parsnips, rutabaga, squash, sunflower, spinach or turnips

    • Tomatoes should not be planted near brassicas or dill.

     

    Do you have any companion planting advice to share? Feel free to comment below.

     

    Some excellent resources on Companion Planting can be found here: Companion Planting | West Coast Seeds, Companion Planting Chart, Map and Guide | Companion Gardening Map & Chart (heirloom-organics.com) (even offers a layout for your garden!)

     

    References:

    Bird, Richard (1996). Companion Planting. Strathearn Books Limited, Toronto, Canada

    Allelopathy - Wikipedia

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