Sunflowers are one of the most beginner-friendly flowers you can grow, but that doesn’t mean they’re totally foolproof. While they’re known for being low-maintenance and cheery, there are a few things first-time gardeners often miss that can lead to sad, floppy stalks or underwhelming blooms. Whether you’re planting them for the bees, the birds, or just because they make your garden look like summer itself, here are 12 things to know before you get started.
1. They need full sun (and lots of it).
This isn’t one of those plants that tolerates “a bit of shade.” Sunflowers need at least 6–8 hours of full, direct sunlight every single day. Anything less, and you’ll likely get smaller blooms and weaker stems. Choose the sunniest spot in your garden—ideally south-facing, with no nearby trees or tall fences casting shadows. If they don’t get enough light, they’ll grow tall and leggy while still looking a bit underwhelming.
2. They grow tall, so plan their position wisely.
Depending on the variety, sunflowers can grow anywhere from 2 to over 10 feet tall. That’s fine, unless they’re suddenly blocking all the light from your veg patch or shading out smaller plants. Place them at the back of a bed or against a wall or fence. Not only will they look great towering over everything else, but they also won’t interfere with the growth of your other sun-lovers.
3. Support is sometimes necessary.
While smaller varieties stand just fine on their own, the bigger ones often need help, especially if you live somewhere windy. Without it, you might walk outside one day to find them bent in half. Use canes, stakes, or even tie them gently to a fence. Just don’t wait until the damage is done. Support early on gives them a better chance of reaching their full height without drama.
4. They grow fast, but need patience at first.
Sunflowers are fairly quick growers once they get going, but don’t be alarmed if they take a little while to sprout. Depending on the temperature and soil, germination can take 7 to 10 days. Once they’re up, though, you’ll almost be able to see them stretch daily. Keep the soil lightly moist during this early stage and protect the seedlings from slugs and snails while they’re small.
5. Sow them directly for best results.
You can start sunflowers indoors, but they don’t always enjoy being transplanted. Their roots grow fast and deep, and disturbing them can stunt their growth or lead to wilting. If your soil’s warm enough (usually from late April onwards in the UK), sow them directly outdoors. You’ll get sturdier plants with stronger roots and less hassle overall.
6. Give them room to grow.
Sunflowers don’t like being cramped. If they’re too close together, they’ll compete for light, nutrients, and water, and none of them will really thrive. Check the seed packet for spacing guidelines, but a good rule of thumb is 30 cm apart for medium varieties, and up to 60 cm for the giants. It makes a big difference later on.
7. They love well-draining soil.
Sunflowers don’t need super fancy soil, but they definitely don’t like soggy feet. Waterlogged roots can lead to rot, and that’s a fast way to lose a whole patch of flowers. If your soil is heavy clay, consider digging in compost or grit to improve drainage. Raised beds or containers with good drainage holes also work well, especially for smaller types.
8. Slugs love young sunflower shoots.
Don’t be fooled by their future size. Sunflower seedlings are like salad to slugs and snails. If you’re not careful, you’ll go to bed with baby plants and wake up to nothing but nibbled stems. Use copper tape, crushed eggshells, or wildlife-safe slug deterrents around the base of young plants. Once they’re bigger, they’re less vulnerable, but early protection is key.
9. Water deeply, not constantly.
Sunflowers don’t need daily watering, but they do appreciate a good soak every few days, especially during dry spells. Their roots go deep, and shallow watering doesn’t reach where it counts. Let the top inch or two of soil dry out between waterings. Once established, they’re actually quite drought-tolerant, but they still grow best with regular deep watering when the weather’s hot.
10. They follow the sun, but not forever.
Young sunflower heads do a thing called heliotropism, which means they literally track the sun from east to west throughout the day. But once they mature, they usually stop moving and settle facing east. That’s why most sunflower photos show them all facing the same way. It’s not magic; it’s biology. Knowing this helps you position them in the best spot to enjoy their blooms yourself.
11. Deadheading keeps them blooming.
If you’re growing branching varieties (the ones with multiple blooms per plant), deadheading spent flowers can encourage new ones to form. It’s simple and keeps your patch looking fresh. For single-stem giants, there’s not much to do once they bloom, but don’t rush to cut them down. Birds like finches love the seeds, so they’re still useful long after the petals fade.
12. You can save the seeds (if the birds don’t get there first).
Once the flowers dry out and the heads go brown, you can harvest the seeds for next year, or leave them for the birds. Either way, they don’t go to waste. If you want to save seeds for planting, cut off the flower heads and let them dry fully. Then rub out the seeds, store them somewhere dry, and you’re set for another sunny season.