How to Grow Sunflowers

Farmer and photographer Lindsey Krebs first fell for sunflowers as a young girl passing a cheery row along a fence each summer. But it wasn’t until she started growing sunflowers herself that she fully came to appreciate their range of colors, easy care, pollinator appeal and cut flower beauty. 

“My first memories of sunflowers were yellow blooms with dark centers,” says Krebs. “Later, I came to know all the different varieties, and that’s what sparked my interest.”

Today, she grows them as part of her cutting fields at Rooted Photo + Farm in London, Ohio, as well as around her house. And her family gets in on the fun too: The kids randomly plant mammoth sunflower seeds in the middle of the family vegetable garden, and her husband plants thousands of a whimsical two-tone variety in an acre patch for photo opportunities and passersby.

We talked with Krebs to learn her tips for sowing sunflower seeds, harvesting their blooms for bouquets and saving seeds for the next season. 

How to Choose Sunflower Seeds

Choosing the right seeds can be daunting, given the dozens of sunflower varieties. Sunflowers come in classic yellow, burgundy, orange, red, chocolate, green, peach and even multi-colored. Krebs explains the plants are grouped in two forms—either single-stem or branching. The single-stem varieties produce one large flower atop a tall stem.  Krebs’ favorite is ProCut White Lite, a pollenless flower, which means a longer vase life and less mess.

Branching varieties, on the other hand, feature an ongoing supply of multiple, smaller blooms. They need more space, so plant them 18” apart. They’re perfect for a whimsical patch, like Krebs’ acre of ‘Autumn Beauty’. Krebs also points out size is another factor. Mammoth sunflower varieties will climb over 10 feet, while dwarf sunflowers only grow to two feet, making them ideal for containers or mixed flower borders. 

Fun Fact: Sunflowers' botanical name is as evocative as their common one: Helianthus derives from Greek for sun (helios) and flower (anthos). 

Where to Plant Sunflowers

Choose a sunny location with at least six hours of direct sunlight. Sunflowers will tolerate poor soil and summer heat, yet perform better in soil amended with compost. Krebs suggests lining them along the west or south side of the house or garage, massing them in a patch, clustering a few near a mailbox, creating a row along a fence or forming a clubhouse-style structure or maze near a child’s play space. They can also be mixed in a flower border with other fast-growing, sun-loving annuals such as castor bean (with coordinating big foliage), hollyhocks (complementary heights) and zinnias (in matching colors). 

Fun Fact: Sunflowers are a good nectar and pollen source for many different pollinators such as bees, who are lured in by the showy outer “ray” petals.

When to Plant Sunflowers

Plant seeds outdoors in spring when day and night temperatures stay above 50 degrees, typically May in the Midwest. Sprouts will emerge in 7-10 days, then grow rapidly as the weather heats up. Depending on the variety, expect to see blooms in 50-90 days. 

Pro Tip: To enjoy continuous blooms, stagger seed plantings over a two- or four-week period or plant a mix of early and late blooming varieties. See “Days to Bloom” on the back of seed packets for timing specifics.

How To Plant Sunflowers

Sunflowers are best sown directly in the ground after the last frost. Simply poke a hole 1-inch deep, drop in a seed then cover the hole. Space branching varieties 18” apart and single-stem varieties 6” apart. Keep the soil evenly watered until seedlings are several inches tall. If birds and other wildlife are a challenge, protect young seedlings with netting or chicken wire until they are 3 inches or more. 

To encourage longer-stemmed blooms on branching varieties, pinch their central buds when plants are knee-high. The pinching will delay blooms by 7-10 days but produce more ideal flowers for cutting. But avoid pinching single-stem varieties; they won’t bloom if pinched.

Many varieties are self-supporting, but others, like the mammoth ones, may need to be staked.  Place a wooden, metal or bamboo stake near the stem, then tie to the stalk with twine or cloth strips. 

Pro Tip: With single-stem sunflowers, experiment with spacing to control flower size. Arrange tightly (4-6” apart) to produce smaller bouquet-size blooms or more loosely (8” or more) to allow for larger blooms.

How to Cut Sunflower Blooms

Harvest blooms as soon as petals start unfolding, even if it is just a few. “Watch for the color,” says Krebs. If you wait until the flowers are fully open, they won’t last as long in the vase. Once cut, strip leaves from the flower stems and immediately place stems in a bucket of water. Indoors, arrange flowers in a clean vase and add a preservative (or a couple drops of bleach) to the water. Sunflowers are known to quickly dirty the water, so change it every two to three days to keep blooms fresh. 

How to Harvest Sunflower Seeds

Each mammoth-style sunflower head contains as many as 1,000 to 2,000 seeds, which makes a nutritious snack for gardeners or their feathered friends. Krebs suggests using a drawstring mesh bag or brown paper bag to protect seed heads from birds until they fully develop. Once the seed heads have browned and turned downward, cut them, leaving 12” stems. Hang the seed heads by the stems to dry (approximately 1 week), then remove seeds by rubbing and catching them in a bowl. The seeds can be roasted to eat in snacks, salads or other dishes; or saved to feed birds in winter. (Krebs makes suet blocks with them.) She also stores heirloom sunflower seeds in her basement until next spring to plant more sunflowers: “It’s a gift that keeps giving.”

Fun Fact: A 100-gram serving of sunflower seeds provides 21 grams of protein plus significant amounts of vitamins E and magnesium.

Resources

For additional growing information and seed supplies, visit Johnny’s Seeds, Sunflower Selections, Sunflower Steve Seed Co. and Baker Creek Heirloom Seed Co.