What to plant in April in Canada: by zone, from the Prairies to the coast

In Canada, planting in April depends entirely on your specific region and hardiness zone. While gardeners in coastal British Columbia are already direct-sowing root crops, Prairie growers are still managing snow and focusing on indoor seed starting. By understanding your local average last frost date and working within your specific zone band, you can successfully launch your spring growing season.

Understanding the Canadian zone system in April

When planning your spring garden, it is important to use the Canadian Plant Hardiness Zone system rather than the American USDA scale. Developed by Natural Resources Canada, the Canadian system is calculated using seven distinct climate variables, including rainfall, wind, maximum temperatures, and the length of the frost-free period. The USDA scale relies solely on minimum winter temperatures, which does not accurately represent the complex growing conditions of the Canadian spring.

In April, the temperature gradient across Canada is vast. While coastal regions are already frost-free, interior and northern regions are still weeks away from their last spring frost. Successful gardening across this range requires dividing your planting tasks by your regional zone band.

Zones 2 to 3: Prairies, Northern Ontario, Quebec, and the North

For gardeners in northern regions and the Prairies, outdoor soils in April remain frozen or waterlogged. The average last frost date in these areas typically falls between late May and mid-June. Outdoor planting is not yet possible, but indoor seed starting is at its peak.

1. Indoor sowing of brassicas and onions

• Cabbage, broccoli, and cauliflower: start these cool-season crops indoors during the first two weeks of April. They require four to six weeks of indoor growth before they can be hardened off and transplanted under cover in May.
• Onions and leeks: if you did not start these in March, sow them immediately in early April. They need a long head start to develop strong root systems and thick stems before transplanting.
• Herbs: sow parsley, thyme, and oregano indoors under grow lights. Keep the soil temperature around 21°C for optimal germination.

2. Preparing for the season

Because of the short growing season in these zones, utilizing indoor space is vital. For detailed strategies on managing these cold climates, consult our guide on zone 2-4 gardening in Canada.

Zones 4 to 5: Interior Ontario, Southern Manitoba, and Quebec Interior

In Zones 4 and 5, April is a transitional month. The snow is melting, and the soil is beginning to thaw, though the average last frost date is still mid-to-late May. Gardeners here balance intensive indoor seed starting with early outdoor soil preparation.

1. Indoor sowing of warm-season crops

• Tomatoes: mid-to-late April is the ideal window to start tomato seeds indoors. Sowing them too early leads to leggy, weak plants, while sowing now ensures stocky, resilient transplants for late May. To choose the right varieties for your short summer, read about the best tomatoes to grow in Canada.
• Peppers and eggplants: start these heat-loving crops indoors during the first week of April. They require a consistent soil temperature of 24°C to 27°C to germinate successfully, making a heated seedling mat worthwhile.

2. Outdoor sowing under cover

If you have a greenhouse, cold frame, or low tunnel, you can begin early outdoor sowing. Refer to our guide on season extension in Canada to learn how to shield crops from freezing overnight temperatures. Sown under cover, hardy greens like spinach, kale, and leaf lettuce can germinate in soils as cool as 5°C.

For a complete timeline of indoor and outdoor sowing, review our resource on when to start seeds indoors in Canada.

Zones 6 to 7: Southern Ontario, the Maritimes, and Fraser Valley

Gardeners in Zones 6 and 7 experience a true arrival of spring in April. The average last frost date typically occurs between late April and mid-May. Soil temperatures are rising, allowing for the first direct outdoor plantings.

1. Direct sowing outdoors

Once the soil has dried sufficiently to be worked without forming heavy, sticky clumps, you can sow hardy seeds directly into the ground:

• Peas: sow shelling, snap, and snow peas directly into the garden in mid-April. Peas thrive in cool spring weather and can tolerate light frosts.
• Spinach and radishes: these are the fastest spring crops. Sow them in shallow drills 1 cm deep. Radishes will be ready to harvest in less than a month.
• Carrots and beets: sow early varieties in late April. Ensure the soil is free of stones and heavy clay to prevent root splitting.

2. Indoor sowing of tender crops

In late April, start warm-season cucurbits indoors, including cucumbers, zucchini, and melons. These crops grow rapidly and should only be kept indoors for three to four weeks before transplanting to prevent them from becoming root-bound.

Zone 8: Coastal British Columbia

Coastal British Columbia enjoys the mildest climate in Canada, with the average last frost date often passing by late March or early April. In this zone, April is a busy month for direct sowing and transplanting outdoors.

1. Direct sowing outdoors

• Root crops: direct-sow maincrop carrots, parsnips, beets, and radishes. Parsnips require a long growing season and should be sown early in the month.
• Leafy greens: sow continuous successions of lettuce, Swiss chard, arugula, and kale every two weeks for a steady spring harvest.
• Brassicas: sow turnip, rutabaga, and mustard greens directly into well-drained garden beds.

2. Planting out transplants and sets

• Potatoes: plant chitted seed potatoes in trenches or deep containers during early April. Draw soil over the emerging green shoots if a rare late frost is predicted.
• Onions and shallots: plant out young onion transplants raised indoors, along with dormant onion and shallot sets.
• Hardened-off brassicas: transplant young cabbage, broccoli, and kale plants into their final outdoor positions, ensuring they are protected from pests like cabbage moths.

For specific regional timelines and coastal microclimate advice, consult our guide on when to plant vegetables in BC.

Essential April gardening jobs across Canada

Regardless of your specific hardiness zone, completing these foundational tasks in April set up your garden for a highly productive season:

1. Warming cold soils

Outdoor soil temperatures lag behind air temperatures. You can accelerate the warming process by covering your planting beds with clear plastic sheeting or black landscape fabric two weeks before sowing. This traps solar radiation, rising soil temperatures by several degrees and drying out excess winter moisture.

2. Hardening off seedlings

Before transplanting indoor-grown seedlings into the garden, you must gradually acclimate them to outdoor conditions. This process, known as hardening off, prevents transplant shock:

• Start by placing seedlings in a sheltered, shady spot outdoors for two hours a day.
• Gradually increase their exposure to sunlight and wind over a period of seven to ten days.
• Ensure they are brought indoors overnight if temperatures are forecast to drop near freezing.

3. Preparing garden beds

As soon as the ground thaws, gently remove winter mulches from perennial beds to allow the soil to warm. Pull any early spring weeds before they have a chance to establish deep roots or set seed. Top-dress your vegetable beds with a 5 cm layer of well-rotted compost, gently raking it into the surface without deep digging to preserve soil structure.