Companion Planting for Alberta Zone 3: Best Pairings for a Healthy Garden
Companion planting is a time-tested gardening method that places plants with beneficial relationships near each other to improve growth, deter pests, and enhance soil health. For those of us gardening in Alberta’s Zone 3, where short growing seasons and cooler temperatures shape our choices, companion planting can make all the difference in cultivating a thriving garden—naturally.
Why Companion Planting Works
Plants, like people, thrive in community. Some plants naturally repel pests, while others share nutrients, shade the soil, or support pollinators. Strategic planting boosts biodiversity and helps reduce the need for chemical inputs.
Natural Pest Control
Certain plants repel insects that tend to attack your vegetables:
- Marigolds + Tomatoes: Marigolds secrete compounds that deter nematodes and aphids. Tomatoes benefit from their protection.
- Basil + Peppers/Tomatoes: Basil repels thrips, flies, and mosquitoes while enhancing tomato flavour.
- Onions + Carrots: Onions deter carrot rust fly, while carrots discourage onion flies.
- Nasturtiums + Cucumbers/Squash: Nasturtiums act as a trap crop, luring aphids and squash bugs away from your main vegetables.
Nutrient Sharing & Soil Improvement
Some plants help others by fixing nitrogen, breaking up soil, or offering ground cover:
- Peas/Beans + Corn: Legumes fix nitrogen in the soil, feeding hungry corn plants.
- Radishes + Carrots: Radishes grow quickly and loosen soil, making it easier for carrots to develop straight roots.
- Lettuce + Tall Crops (like Corn or Sunflowers): Tall plants offer light shade, helping lettuce stay cool and slow to bolt.
Companion Plant Pairings (Good Neighbours)
| Plant | Good Companions | Benefits |
|---|---|---|
| Tomatoes | Basil, Marigold, Borage, Carrots, Garlic | Pest control, improved flavour, pollinator attraction |
| Carrots | Onions, Leeks, Chives, Peas, Lettuce | Deters carrot fly, soil aeration, shade for cool growth |
| Cabbage | Dill, Onion, Sage, Nasturtium, Beets | Repels cabbage moths, improves nutrient use |
| Beans | Corn, Cucumbers, Radish, Strawberry | Fix nitrogen, help shade soil |
| Peas | Carrots, Radish, Turnip, Lettuce | Nitrogen fixing, soil loosening |
| Cucumbers | Nasturtium, Sunflowers, Beans, Dill | Shade, pollinator attraction, pest repellent |
| Beets | Onions, Lettuce, Garlic | Pest control, soil conditioning |
| Lettuce | Radishes, Carrots, Strawberries, Beets | Shade-loving, shares space well |
| Corn | Beans, Squash, Sunflowers | Classic “Three Sisters” method, structural support |
| Zucchini | Nasturtium, Borage, Corn | Attracts beneficial insects, repels pests |
| Spinach | Strawberries, Peas, Radishes | Shade and pest support |
| Potatoes | Beans, Corn, Cabbage, Horseradish | Pest deterrence and soil synergy |
Bonus Tips:
- Nasturtiums and Marigolds are all-star companions: easy to grow and great for pest control.
- Borage is wonderful for strawberries, squash, and tomatoes—boosts resilience and pollination.
- Rotate crops annually to prevent pest buildup and soil depletion.
Zone 3 Tips for Success
- Choose cold-hardy and short-season varieties.
- Stagger plantings to maximize use of space and time.
- Use raised beds or row covers to extend the season and offer protection.
Companion Planting Resources for Alberta Gardeners
- Alberta Agriculture and Irrigation – Home Gardening Resources
https://www.alberta.ca/home-gardening.aspx - The Old Farmer’s Almanac – Companion Planting Chart
https://www.almanac.com/companion-planting-chart-vegetables - The Organic Gardening Catalogue – Companion Planting Explained
https://www.organiccatalogue.com/blog/companion-planting-guide - West Coast Seeds – Companion Planting Guide
https://www.westcoastseeds.com/blogs/garden-wisdom/companion-planting-guide - Gardening at USask – Prairie Gardening Guide
https://gardening.usask.ca/articles-how-to/companion-planting.php - Seeds of Diversity Canada – Companion Planting in Practice
https://seeds.ca/gardening/companion-planting - Get Growing Alberta – Companion Planting Tips
https://getgrowingalberta.com/companion-planting/
Non-Companion Plants (Poor Neighbours)
| Plant | Avoid Planting With | Why |
|---|---|---|
| Tomatoes | Corn, Potatoes, Fennel, Cabbage | Compete for nutrients, attract similar pests |
| Carrots | Dill, Parsnips | Dill may stunt growth; shared pests with parsnips |
| Cabbage | Strawberries, Tomatoes | Competes for nutrients, attracts pests |
| Beans | Onions, Garlic | Onion family stunts bean growth |
| Peas | Onions, Garlic | Inhibits pea growth |
| Cucumbers | Potatoes, Aromatic herbs (like Sage) | May inhibit cucumber growth |
| Beets | Pole Beans | Growth suppression |
| Lettuce | Parsley | Can bolt early or compete for root space |
| Potatoes | Cucumbers, Pumpkin, Tomatoes, Sunflowers | Disease and pest risks (blight, beetles) |
| Fennel | Most plants | Allelopathic—suppresses growth of nearby vegetables |
Companion planting is more than a technique—it’s a philosophy of balance and biodiversity. By mimicking natural ecosystems, we support healthier plants, reduce our reliance on chemicals, and create a more resilient garden.
Visit the Trochu Arboretum this season to see examples of companion planting in action and ask our volunteers for tips on what’s working in our local beds!
Happy growing, Trochu!
—The Trochu Arboretum Team
Leave a Reply