In “You’ve Got Mail,” Meg Ryan’s character notes that daisies are the friendliest flower. Ahem, really, Meg? How could you have discounted the sunflower so easily? It’s okay; we’ll forgive you and your perfect hair.
Sunflowers are one of those plants that have captured the hearts of gardeners, famous artists and baseball players the world over. Did I mention that they’re so easy to grow?
It’s no wonder so many of us choose to plant these gloriously friendly flowers in our gardens. But before you start tossing sunflower seeds around like they’re nature’s confetti, there are a few simple tips you should know to grow them well.
As any experienced gardener can attest, it’s one thing to grow a plant; it’s another to grow a plant so it thrives.
And because I love fun and weird facts and I’ve been sucked down a Chernobyl rabbit hole lately, I’ve also included some pretty wild facts about sunflowers that you may not know. (This will explain the Chernobyl comment later.)
1. They’re Called Sunflowers for a Reason
Let’s start with the obvious. Sunflowers need sun. All the sun.
This is one plant that can take the heat and will thank you for it, even that insane afternoon sun that bakes most plants.
So yes, while most seed packets will tell you sunflowers need at least six hours of full sun, just remember that’s the bare minimum to get them to grow. If you want them to thrive and crank out flowers or seeds like there’s no tomorrow, then ideally, you’ll want to grow them somewhere they will receive 8+ hours of full sun a day.
Wild Fact:
Sunflowers will move their heads, tracking the sun from east to west during the day. Then, what’s even cooler (at least I think so anyway) is overnight, they will slowly turn back, facing the east, waiting for the rising sun.
Sunflowers don’t just follow the sun when growing—they also have an internal circadian clock, kind of like we do, which allows them to anticipate the sun’s movement. If you move a sunflower pot to face a different direction? They’ll actually get confused and stop tracking the sun until they recalibrate. Amazing!
Scientists call this behavior heliotropism. This movement gives them maximum sun absorption, which in turn boosts growth, flower development, and attracts more pollinators.
2. Sunflowers Are Not Picky, But They Appreciate the Effort
Sunflowers are the chill house guest. No, you don’t need a spotless house when they visit, but they’re super appreciative if you tidy up. When it comes to unfussy garden tenants, they’re hard to beat. They will grow just about anywhere. However, just like their sun requirements, if you want them to thrive, make sure they have loose, well-draining soil.
Mix in some compost, worm castings or a little mycorrhizae when you plant them and keep them well-watered when they’re tiny seedlings. Luckily, once they get growing they develop deep taproots that make them surprisingly drought-resistant.
Wild Fact:
Okay, here’s where my Chernobyl obsession comes in. Did you know that sunflowers have been used to clean up radioactive soil? After the Chernobyl and Fukushima disasters, scientists planted massive fields of sunflowers to extract heavy metals and radioactive isotopes from the soil nearby.
Sunflowers are part of a group of plants called hyperaccumulators, which means they attract heavy metals in the soil and draw them up into their stems. Once the sunflowers did their fancy trick, they were harvested and destroyed safely in a process called pyrolysis. (Heated to a high temperature without oxygen.) (You can read more about sunflower radiation removal here.)
Friendly, beautiful and nature’s nuclear disaster remediators.
3. Keep Those Cut Flowers Coming!
If you plan on growing sunflowers specifically for cut flowers, you’ll want to use a method called succession planting, which means you continuously plant new batches over the growing season. (Lindsay explains it here.)
Begin in early spring, as soon as you’ve hit your expected last frost date or when the soil has warmed to around 55 degrees. Sow the seeds 1 to 2 inches deep. Then, continue planting new seeds every two weeks into early summer.
By spreading out your harvest, they will bloom continuously through the summer to brighten your home or to sell.
Wild Fact:
A sunflower is actually two types of flowers in one. The petals are known as ray florets. These are the sunny parts that attract pollinators and us to the plant. The inner part is actually hundreds, sometimes thousands, of tiny flowers called florets. Each one will become a seed if pollinated. These tiny flowers are called disk florets and are all completely self-contained, individual flowers.
4. Get Staked or Be Ready for A Broken Heart & Broken Stems
My dad loved growing sunflowers. He always grew the biggest varieties he could find. He used to tell me about the ones he grew when “your mom and I lived in Kentucky. They were taller than the garage. I had to use a hatchet to cut them down at the end of the summer.”
Everyone in the family knows Dad likes to embellish his stories. So, I have no idea if the hatchet bit was true, but it sounds like something he would do.
If you plan on growing mammoth sunflowers—those 8- to 12-foot varieties with heads the size of dinner plates—you have to stake them. Let me tell you, all it takes is one good summer storm to put an end to your dreams of sunflower seeds. They will even snap under the weight of their own heads if you don’t tie them up.
There’s nothing quite like the heartbreak of having a great growing season, with huge sunflowers and finding them all snapped in half after a thunderstorm. Stake them early and check them throughout the summer to make sure they’re supported properly.
Wild Fact:
Some wild sunflowers are just plain aggressive, even considered invasive in some states. There are wild perennial varieties that will spread like wildfire, dominating roadsides and abandoned lots with reckless abandon.
One of my favorite summer walks near me is on state game lands, where hundreds of sunflowers grow wild. It’s beautiful and full of birds!
5. Snacks Anyone? Not in This Garden!
Birds, squirrels, chipmunks, and deer all love sunflower seeds. As if your garden wasn’t tempting enough! To prevent nighttime snacking, you should cover freshly planted seeds with row cover or mesh until the seedlings are well-established and less vulnerable.
Wild Fact:
The local critters aren’t the only ones with a penchant for chewing sunflower seeds. Move over peanuts; sunflowers are the snack of choice among baseball players. For decades, the sight of players snacking on sunflower seeds and spitting out the shells during games has become as common as fans booing the umpire. Sunflower seeds became popular as chewing tobacco fell out of fashion among players. (Thank heavens!) You can read more about it here.
6. Want More Blossoms? Give ‘Em a Pinch
If you’re growing a branching variety of sunflower, pinch the central stem when the plant is around 12–18″ tall. Just like with tomatoes and peppers, this encourages the plant to produce more side stems, which will give you more flowers and a longer bloom season.
This only works with branching varieties, though. If you pinch the top of a single-stem variety, you’ll put a quick end to your flower.
Wild Fact:
Sunflowers are good at Math. The spirals you see in the flower’s center follow the Fibonacci sequence (1, 1, 2, 3, 5, 8…). Not only is it a beautiful pattern, but it’s the most efficient way of packing all those sunflower seeds into the space available—form and function in one showy package.
7. It’s Time to Pick!
If you’re saving seeds for eating or for planting next year, wait until the back of the sunflower head turns yellow or brown and the seeds have earned their stripes before harvesting.
If you want cut flowers, cut at an angle and cut the flower when the petals (the ray florets) are just starting to lift from the center but haven’t fully opened. This will give you the longest life, especially if you follow Madison’s advice here.
Wild Fact:
Did you know that sunflower oil is the most commonly used cooking oil in the world? Ukraine and Russia are two of the largest producers. So, if you’re wondering why sunflower oil prices are high, now you know.
Of course, you don’t have to stick with the traditional sunflower color of golden yellow. There are so many beautiful varieties to choose from. For more helpful information about growing sunflowers, plus some great varieties to try, click here.
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