Sunflowers are the divas of the summer garden—tall, showy, and always turning heads (and faces) toward the sun. Whether you're growing them for pollinators, bouquets, seed-saving, or just for the joy of seeing something huge sprout from a tiny seed, sunflowers are beginner-friendly and rewarding to grow.
Here’s how to get started—and keep them blooming all season long.
Start With the Seed: When and How to Sow
Sunflower seeds can be sown in three ways:
1. Direct Sowing (Most Common)
Once the soil has warmed to at least 10°C (50°F), usually around mid- to late-May in most parts of Canada, you can plant sunflower seeds directly into the ground. Pick a full sun location and space seeds 6–12 inches (15–30 cm) apart, depending on the variety.
2. Greenhouse or Indoor Start
Want a jump start? Sow seeds indoors in peat pots or cell trays 2–4 weeks before your last frost. They transplant best when young—don't let them get rootbound or leggy indoors. Harden them off before planting outside.
3. Winter Sowing
Yes, you can winter sow sunflowers! Plant them in a milk jug or other container greenhouse in late winter and let nature do the timing. Once conditions are right, they’ll germinate on their own. This method works best and gives a head start without babying seedlings indoors.
Succession Sowing: Flowers for Months, Not Weeks
One of the best tricks for keeping sunflowers blooming all summer? Succession sowing.
Instead of planting all your seeds at once, sow a small batch every 2–3 weeks until midsummer. This ensures a steady supply of blooms, especially helpful for cut flower growers and bouquet lovers.
- Early sowing gives tall, strong early bloomers.
- Mid-season sowings fill in the gaps as earlier ones fade.
- Late-season sowings bloom in late August to September—perfect for fall arrangements or seed-saving.
Just make sure your last sowing is at least 70 days before your first frost, depending on the variety's maturity time.
Here’s an example of a sunflower succession sowing schedule for Calgary, Alberta (Zone 3) with a first frost average date of September 11th:
- Planting #1: May 15: Direct Sow, Greenhouse or Winter Sown
- Planting #2: June 1st - Direct Sow
- Planting #3: June 15th - Direct Sow
- Planting #4: July 1st - Direct Sow
- Planting #5: July 15 - Direct Sow ( ~70 days before first frost)
Best Varieties for Succession: Single Stem Sunflowers
Single stem sunflowers are particularly well suited for succession sowing (plantings 2 – 5). These sunflowers produce one large bloom per plant—perfectly timed and uniform. They grow fast and reliably, making it easy to stagger plantings and plan for a continuous harvest.
Look for varieties like the Pro-Cut series of Sunflowers.
These are florist favourites, thanks to their strong stems, predictable timing, and clean growth habit.
In contrast, branching sunflowers produce multiple smaller blooms over a longer period, but they mature more slowly and take up more space. They’re great for backyard cutting gardens or pollinator beds, but not ideal for tightly timed successions.
Consider planting the branching type sunflowers in Planting #1.
Tips for Happy, Healthy Sunflowers
- Full sun is non-negotiable. Sunflowers need 6–8 hours a day.
- Good drainage is key. They don’t like soggy roots.
- Don’t over-fertilize. A little compost is great, but too much nitrogen = more leaves, fewer flowers.
- Stake the tall guys. Especially if you're growing giants like Mammoth Grey Strip or in windy areas.
Harvesting and Seed Saving
Cut sunflowers early in the day when petals just start to unfurl. For seed-saving, let heads dry on the stalk or bring them indoors once the back of the flower turns brown and papery. Rub out the seeds and store them in a cool, dry spot.
Whether you’re sowing just a few for pollinators or filling a whole fence line with colour, sunflowers are one of the easiest (and cheeriest!) flowers to grow from seed. With a little planning and a few staggered sowings, you’ll have sunny blooms from early summer right into fall.
Browse our full Sunflower Plant Seed collection here.