Annual sunflower varieties have to start their journey from scratch every single year. While you could head to the garden center and buy starts every spring, that gets pretty pricey after a while. Growing them from seed at home is way more budget-friendly! If you get a few key things right, you’ll have a garden full of golden blooms in no time.
The Best Time to Start Your Seeds
Timing is everything when it comes to sunflowers. Since annuals only have one growing season to reach their full size, they need every single day they can get. However, because they are not frost-hardy, you can’t rush them into the ground too early.
- Wait until late April to sow directly outdoors.
- Before then, the soil is too cold and late frosts are a real threat.
- Cold soil can prevent seeds from germinating.
- Young sprouts will freeze if a cold snap hits.
If you want a head start, you can begin growing sunflowers indoors as early as March. This kickstarts their growth and rewards you with a much earlier blooming season.
Sowing Directly in the Garden
Young sunflowers aren’t big fans of being moved; transplanting can actually set their development back. For the best results, sow your seeds directly in a full-sun location where they can stay put for the next few months.
- Loosen the soil deeply (sunflowers have long taproots!).
- Mix in some mature compost or horn meal for nutrients.
- Sow 3-5 seeds together in clusters and cover with soil.
- Planting depth: about 1 inch (3 cm) in heavy clay soil, or 2 inches (5 cm) in loose soil.
- Space your clusters 15-28 inches (40-70 cm) apart, depending on how big the variety gets.
- You can cover the spot with a light layer of mulch or leaves to keep it warm.
- Keep the area moderately moist.
Once the first sets of true leaves appear, pick the strongest seedling in each cluster and pinch off the others.
Starting Sunflowers Indoors
Starting seeds indoors should happen in March. Here’s how to do it right:
- Fill a large seed tray or small individual pots with high-quality seed-starting mix.
- Poke 3-5 seeds about 1 inch (2 cm) deep into the soil.
- If using a tray, space the seeds about 2 inches (5 cm) apart.
- Cover with soil and place the containers in a bright, warm spot.
- Keep the soil consistently moist but not soggy.
- Once the seeds have sprouted and have their first leaves, it’s time to thin them out. Remove the weakest ones so the strongest plants have their own pots.
- Water your young plants regularly, but make sure they have good drainage.
- Start fertilizing once a week.
- Wait until after the last frost (around mid-May) to plant them outside.
Pro Tip:
You can totally grow sunflowers on a balcony! To make it work, give them a pot that is not just wide, but very deep. And of course, make sure they get plenty of sunshine!
