Friends can help you out during difficult times. Plants can do the same for each other. In this activity, find out how growing different plants together can help defend against garden pests— chemical spray free!

You will need

  • Flower seeds, such as marigolds, cosmos and calendulas
  • Herb seeds, such as basil and garlic
  • Veggie seeds, such as lettuce, spinach and tomato
  • Soil
  • Water


This activity involves going outside and touching garden soil. Be sun-safe, ask an adult to supervise you and wash your hands thoroughly after this activity.

outdoor hazard icon

What to do

  1. Discuss with a parent about where you can create a little veggie patch. This could be an empty spot in your backyard or even pots on a balcony. It’s best to pick a spot that gets 5 to 6 hours of sunlight each day.

  2. Pick a mix of flower, herb and veggie seeds, such as marigolds and carrots, or garlic and leafy greens.

  3. Make a shallow hole in the soil, and plant one of your selected seeds into it. Cover the hole with a small handful of soil.

  4. Repeat step 3 for each of your seeds, alternating between different plant seeds until you’ve filled up your little veggie patch! Make sure you give enough space between each hole so that your plants have room to grow (roughly 20-25cm should work).

  5. Water your little patch daily or so, keeping it moist until you see your seeds sprout.

  6. Keep watering your patch when it dries out. With a bit of patience, you can start harvesting some delicious veggies after a few months.

What’s happening?

The science of companion planting, sometimes known as “allelopathy” (uh-lee-lop-uh-thee), is based on how plants chemically and physically work together. Many plants release chemical substances into their surroundings to defend themselves. And just like good friends, different plants can strike up a good chemistry between each other to form an alliance against pests and diseases.

Marigolds are superhero companions that can help protect a lot of other plants. Marigolds release pyrethrum (PIE-ree-thrum) and limonene (lim-oh-neen) compounds, which smell unpleasant to pests such as aphids and nematode worms. Garlic, which has a strong smell to us, also releases stinky sulphur compounds that can keep other garden pests away.

Some plants, such as violets and alyssums that sprawl across the soil, can act as a living mulch and reduce water evaporation from soil. This means less watering for your plants! By mixing different plants together, you also create a more balanced mini habitat with lots of different shapes, colours and resources for wildlife— just like natural environments.

But sometimes friendships might not work out, and this can be true for some plants. Some plants are often targeted by similar pests and diseases and planting them together can increase their risk of attracting pests. Some plants also have different growing needs and might compete for space or nutrients. When you pick seeds to grow, make sure you include a good mix of at least 3 or 4 different plants, and give them space to grow according to the instructions on your seed packets.

If you know any companion plants that work well together, tell us in the comments!

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