When to Plant Sunflowers in Canada 2026
Sunflowers are one of the most rewarding crops for Canadian gardeners — and one of the most forgiving. Plant them at the right time and they'll grow with minimal fuss from mid-May through September. Plant too early and a late frost kills them; wait too long and they won't mature before fall.
This guide gives you exact planting windows for every Canadian zone for 2026.
Quick Answer: When to Plant Sunflowers
Direct sow sunflower seeds after your last frost date, when soil is at least 10°C (50°F):
| Region | Zone | Direct Sow Window |
|---|---|---|
| BC Lower Mainland | 7–8 | April 15 – May 10 |
| Southern Ontario / Quebec | 6 | May 10 – June 1 |
| Central Ontario, NS, NB | 5b | May 15 – June 5 |
| Prairies (southern) | 4–5a | May 20 – June 10 |
| Calgary, Northern Ontario | 3b–4a | June 1 – June 15 |
| Northern Canada | 3a | June 10 – June 20 |
Use the MyGardenPlanner.ca frost date calculator to confirm your exact last frost date by city.
Should You Start Sunflowers Indoors?
For most Canadian zones, direct sowing is recommended. Sunflowers develop a deep taproot that doesn't tolerate transplanting well.
When to start indoors: Only in zone 3, or when you want to push the season. Use 7–10 cm (3–4 inch) peat pots — transplant the entire pot outdoors without disturbing roots. Start 2–3 weeks before last frost.
Best Sunflower Varieties for Canadian Climates
Short-Season (55–70 days) — Best for Zones 3–5
| Variety | Days | Notes |
|---|---|---|
| Sunrich Orange | 55 | Cut flower favourite |
| Music Box Mix | 60 | Multi-branching, compact |
| Teddy Bear | 65 | Dwarf, fluffy heads |
| Pacino | 55 | Container-friendly |
Standard Season (75–85 days) — Zones 5–8
| Variety | Days | Notes |
|---|---|---|
| Mammoth Russian | 80 | Tall, edible seeds |
| Lemon Queen | 75 | Pale yellow, pollinator magnet |
| Velvet Queen | 75 | Deep burgundy, dramatic borders |
Prairie tip: Stick to 55–65 day varieties in zones 3–4. Mammoth Russian won't finish before frost in Calgary or Saskatoon.
How to Plant Sunflowers
Site: Full sun (minimum 6 hours, 8 hours ideal), well-drained soil, some wind shelter for tall varieties.
Depth: 2.5 cm (1 inch)
Spacing:
- Dwarf varieties: 30 cm (12 inches) apart
- Standard varieties: 45 cm (18 inches) apart
- Giant varieties (Mammoth): 90 cm (36 inches) apart
Soil: Sunflowers aren't fussy — average garden soil works well. Avoid high-nitrogen fertilizers; they push leaf growth at the expense of flowers. A balanced fertilizer (10-10-10) at planting is sufficient.
Succession Sowing for Continuous Blooms
Want cut flowers from July through September? Sow in 2-week intervals from your last frost date through mid-June. Three successions give you blooms across the full summer.
Watering and Care
Sunflowers are drought-tolerant once established. Water deeply during germination and early growth, then reduce. Overwatering causes crown rot and floppy stems. Stake tall varieties when they reach 60 cm (24 inches) in windy locations.
Pests to Watch in Canadian Gardens
- Deer and rabbits — net young plants in rural settings
- Squirrels and birds — cover ripening heads with mesh or paper bags to save seed
- Aphids — knock off with a strong spray of water
When Will They Bloom?
| Zone | Sow Date | Expected First Bloom |
|---|---|---|
| Zone 8 (BC coast) | April 15 | Late June |
| Zone 6 (S. Ontario) | May 10 | Mid-July |
| Zone 5 (C. Ontario) | May 20 | Late July |
| Zone 4 (Prairies) | June 1 | Mid-August |
| Zone 3 (North) | June 10 | Late August |
Plan Your Sunflower Schedule at MyGardenPlanner.ca
Use the free planting calculator at MyGardenPlanner.ca to get your city's exact last frost date and calculate your sunflower sow date in seconds. For succession planning across multiple beds, the Home Gardener plan at mygardenplanner.ca lets you schedule multiple sow dates with reminders — so you never miss the window for a fresh batch of blooms.
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