Why We Can't (Exactly) Predict Sunflower Season
Every year, one of the most common questions we hear is:
“Are the sunflowers blooming yet?”
And we totally get it! We wish we could set the dates at the beginning of the year, circle them in big yellow marker, and guarantee a picture-perfect field right on schedule.
But here’s the thing: Mother Nature runs this show.
So why is sunflower season more of a guestimate than a guarantee?
Planting Date
We plant our seeds in spring, but the actual start date depends on when the soil is dry enough to work with. Some years we get a head start, other years we’re waiting on the mud to dry. This spring—like any typical Iowa spring—was a roller coaster. We started off dry. Then we got wet. Then we got even wetter.
The August Sunflower Experience ended up split into parts 1 & 2 this year because Mother Nature was up to her usual shenanigans. Eric typically plants the first round of August sunflowers, then waits 4–5 days to plant the next round, but this year he had to wait longer because of rain. We kind of liked having a bit of a break between the rounds of blooms in August. What did you think? Let us know!
You might be thinking, “Isn’t it good to plant when the ground is wet?” And it’s true—seeds do like a drink of water after planting. But if the ground is too wet, there’s a risk of the soil hardening and crusting over, making it difficult for tiny sunflowers to break through and grow.
Soil Temperature
Sunflowers are sun-lovers, but they’re picky. They won’t even think about germinating—or starting to grow—until the soil temperature hits at least 50°F. No warm toes = no flowers. With all the hot weather we’ve had this summer, it’s easy to forget that this spring was c-o-o-l-d.
Growing Degree Days (GDD)—The “Secret Sauce”
Think of this like a sunflower’s version of a Fitbit. Every day that’s warm enough, they track their “steps” toward blooming. Cooler days = slower progress. Hot stretches = flower frenzy.
Every plant has a base growing degree temperature. For sunflowers, it’s 44°F. When the average daily temperature is above that, the plant is soaking up heat and growing as fast as Richard Simmons dancing in an aerobics class. If temps are below the base, the poor plant hunkers down like Eeyore on a cloudy day, waiting for something worth getting excited about.
We aimed to have sunflowers blooming over the 4th of July weekend, but we were off by a week thanks to the brisk spring temps. Our poor sunflowers just weren’t getting enough “steps” in.
Heat Speeds Things Up
Once they’re growing, hot weather can really hustle them along. Sometimes they bloom earlier than expected—and sometimes they wrap up sooner, too. (Looking at you, 90-degree week during the July Sunflower Experience!)
So, while we can give you a ballpark idea of when the Sunflower Experience will happen, we can’t set it in stone months ahead. Instead, we keep a close eye on the fields and post regular updates as the blooms approach.
One thing’s for sure—when the sunflowers decide it’s showtime, it’s game ON.
