Growing Sunflowers

How to Plant, Grow, and Care for Sunflowers

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With bright blooms that go from mid-summer to early fall, sunflowers say “summer” like no other plant. Our Sunflower Growing Guide covers everything from planting to cutting flowers to harvesting seeds!

Sunflowers (Helianthus annuus) is an annual plant with a large daisy-like flower face. Its scientific name comes from the Greek words helios (“sun”) and anthos (“flower”). The flowers come in many colors (yellow, red, orange, maroon, brown) but they are commonly bright yellow with brown centers that ripen into heavy heads filled with seeds.

Here and yonder, high and low,
Goldenrod and sunflowers glow.
–Robert Kelley Weeks (1840–76)

How Long Do Sunflowers Take to Bloom?

A fairly fast-growing flower, most sunflower varieties mature in only 85 to 95 days. The largest sunflower varieties grow to over 16 feet in height, while smaller varieties have been developed for small spaces and containers and rarely grow larger than a foot tall! The flower heads can can reach over 12 inches in diameter within the large seeded varieties.

Sunflowers are heliotropic, which means that they turn their flowers to follow the movement of the Sun across the sky east to west, and then returns at night to face the east, ready again for the morning sun. Heliotropism happens during the earlier stages before the flower grows heavy with seeds.

Very few plants are as heat-tolerant, resistant to pests, and simply beautiful. Sunflowers make excellent cut flowers and many are attractive to bees and birds.

At the end of the season, it’s easy to harvest sunflower seeds for a tasty snack or for replanting (see instructions below). Learn more about why you should start growing these happy flowers in your garden.

Planting

When to Plant Sunflowers

It’s best to sow sunflower seeds directly into the garden (or outdoor containers) after the danger of spring frost has passed anytime after soils have warmed to 50°F.
In most regions, this will fall between April and mid-July. In the south, this will probably occur in mid-March or early April.

Choosing & Preparing a Planting Site

Find a sunny spot! Sunflowers grow best in locations with direct sunlight (6 to 8 hours per day); they require long, hot summers to flower well.
Choose a location with well-draining soil. It shouldn’t pool water after it rains.
Sunflowers aren’t picky but the soil can’t be too compact. They have long tap roots that need to stretch out; in preparing a bed, dig down 2 feet in depth and about 3 feet across.
They’re not too fussy when it comes to soil pH either. Sunflowers thrive in slightly acidic to somewhat alkaline soil (pH 6.0 to 7.5).
Sunflowers are heavy feeders, so the soil needs to be nutrient-rich with organic matter or composted (aged) manure. Or, work in a slow release granular fertilizer 8 inches deep into your soil.
If possible, plant sunflowers in a spot that is sheltered from strong winds, perhaps along a fence or near a building. Larger varieties may become top-heavy and a strong wind can be devastating.
Before planting, decide whether or not you want to grow a fun sunflower tower.

Sunflowers

Planting Sunflower Seeds

Sunflowers should be planted 1 to 1-½ inches deep and about 6 inches apart after the soil has thoroughly warmed. If you wish, you can plant multiple seeds and thin them to the strongest contenders when the plants are six inches tall.
Give plants plenty of room, especially for low-growing varieties that will branch out. Make rows about 30 inches apart. (For very small varieties, plant closer together.)
A light application of fertilizer mixed in at planting time will encourage strong root growth to protect them from blowing over in the wind.
Experiment with plantings staggered over 5 to 6 weeks to keep enjoying continuous blooms.
If you see birds scratching around for the seeds, spread netting over the planted area until seeds germinate. See more ways to keep birds away from your garden.

Check out this video to learn how to plant sunflowers:

Care

Caring for Sunflowers

While the plant is small, water around the root zone, about 3 to 4 inches from the plant. To protect the plant, it may help to put snail or slug bait around the stem.
Once the plant is established, water deeply though infrequently to encourage deep rooting. Unless the weather is exceptionally wet or dry, water once a week with several gallons of water.
Feed plants only sparingly; overfertilization can cause stems to break in the fall. You can add diluted fertilizer into the water, though avoid getting the fertilizer near the plant’s base; it may help to build a moat in a circle around the plant about 18 inches out.
Tall species and cultivars require support. Bamboo stakes are a good choice for any plant that has a strong, single stem and needs support for a short period of time.

Red sunflower. Photo by Chris Burnett

Pests/Diseases

Birds and squirrels will show interest in the seeds. If you plan to use the seeds, deter critters with barrier devices. As seed heads mature and flowers droop, you can cover each one with white polyspun garden fleece.
If you have deer, keep them at bay with a tall wire barrier. Curious deer may bite the heads off of young sunflowers.
Sunflowers are relatively insect-free. A small gray moth sometimes lays its eggs in the blossoms. Pick the worms from the plants.
Downy mildew, rust, and powdery mildew can also affect the plants. If fungal diseases are spotted early, spray with a general garden fungicide.

Harvest/Storage

Cutting Sunflowers for Bouquets

For indoor bouquets, cut the main stem just before its flower bud has a chance to open to encourage side blooms.
Cut stems early in the morning. Harvesting flowers during middle of the day may lead to flower wilting.
Handle sunflowers gently. The flowers should last at least a week in water at room temperature.
Arrange sunflowers in tall containers that provide good support for their heavy heads, and change the water every day to keep them fresh.

Dried sunflower heads

Harvesting Sunflower Seeds

At the end of the season, harvest sunflower seeds for a tasty snack and or to replant or to feed the birds in the winter! Read all about harvesting sunflowers here.

Let the flower dry on or off the stem until the back of the head turns brown, the foliage turns yellow, the petals die down, and the seeds look plump and somewhat loose.
With sharp scissors or pruners, cut the head off the plant (about 6 inches below the flower head). Place in a container to catch loose seeds.
Lie the sunflower head on a flat, clean surface and grab a bowl to hold the seeds.
To remove the seeds, simply rub your hand over the seeded area and pull them off the plant or you can use a fork. Another way to remove them is to rub the head of the sunflower across an old washboard or something similar. Just grip the head and rub it across the board as if you were washing clothes.
If you are going to harvest the seeds for roasting, you can cover the flowers with a light fabric (such as cheesecloth) and a rubber band to protect the heads from the birds.
Alternatively, you can cut the flower head early and hang the heads upside down until the seeds are dry; hang indoors or in a place that’s safe from birds and mice.
Rinse sunflower seeds before laying out to dry for several hours or overnight.
If you’re saving seeds to replant, store them in an airtight container in a cool, dry place until you are ready to plant.

Learn how to roast seeds in the cooking notes below.

Recommended Varieties

Everyone is familiar with the huge sunflowers that grow on towering eight-foot-tall stalks. But did you know that some varieties top off at a modest 15 inches?

The towering ‘Mammoth’ variety is the traditional giant sunflower, sometimes growing to more than 12 feet tall. Its seeds are excellent for snacks and bird feeders, too.
‘Autumn Beauty’: One of the most spectacular cultivars, the ‘Autumn Beauty’ has many 6-inch flowers in shades of yellow, bronze, and mahogany on branching stems up to 7 feet tall.
‘Sunrich Gold’: A great flower for bouquets and arrangements, this sunflower grows to be about 5 feet tall and produces a single 4- to 6-inch flower. The big, no-mess, pollenless flowers have rich, golden-yellow rays and green-yellow centers.
‘Teddy Bear’: Just 2 to 3 feet tall, this small sunflower is perfect for small gardens and containers. The fluffy, deep-gold, 5-inch blossoms last for days in a vase.

Wit & Wisdom

Some people call sunflowers the “fourth sister,” in reference to the Three Sisters: corn, beans, and squash.
Some cultures see sunflowers as a symbol of courage.
Sunflowers were not only used for cooking by Native Americans, but also for healing (the oil was used to cure skin ailments) and making clothing (yellow dye was made from the flower petals and black or blue dye from the seeds).
Need a bird feeder? Save whole, dry sunflower heads and set them out in winter. Birds will gladly pick at the delicious seeds!
Save thick sunflower stems and dry them for winter kindling.
An anonymous buyer paid over $39 million in 1987 for Vincent van Gogh’s Sunflowers.
The tallest sunflower ever recorded was grown in Germany in 2014. It measured in at a stunning 30 feet and 1 inch tall!
Kansas is “The Sunflower State.”

Cooking Notes

Just one ounce of sunflower seeds contains about 6 grams of protein and 14 grams of oils. The fats are almost entirely unsaturated with 9g of polyunsaturated and 3g of monounsaturated fats per ounce (NSA). The oil is high in linoleic acid and is a good source of vitamin E.

Some varieties produce small black seeds that are used in cooking oil, margarine, cosmetics, and animal feed; they are the best sunflower seeds for attracting the greatest variety of songbirds.
The bigger, striped seeds are grown for snacking and as an ingredient in bread and health foods. They, too, are used for feeding birds, especially larger species, such as jays and mourning doves.

How to Roast Sunflower Seeds

Re-soak seeds overnight in salted water. Run through a strainer and dry on a layer of paper towels.

Bake for 25 to 30 minutes at 325 degrees on a baking sheet. Seeds should be spread out in a single layer. Stir frequently during the baking and remove seeds when they look slightly browned. Don’t burn!

That’s it! You can all some olive oil, salt, spices to your roasted seeds if you wish.

Or, you can also make suet cakes for the winter birds! See how to make suet.

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Reader Comments

Hi, DogFoodie: It's perfectly

Hi, DogFoodie: It's perfectly OK to cut them back now. Be sure to save the seedheads for wildlife now or the (dried) seeds for yourself to plant next year (if you don't have a hybrid).

Thank you! I'm on it! I

Thank you! I'm on it! I just came in from outside after getting caught up in some mindless weeding after another downpour this afternoon. No better time to weed! I'm shocked by how spent several of my pants look this year. The sunflowers will be out of there tomorrow. The buddleia will be grateful for the breathing room!

THIS IS THE 2ND SEASON MY

THIS IS THE 2ND SEASON MY SUNFLOWERS GREW BUT WITH NO FLOWER. I STARTED THEM FROM SEEDS 2 SEASONS AGO, THE PLANT GREW WTIH NO FLOWER. THE PLANTS CAME BACK THIS YEAR AGAIN WITH NO FLOWERS.
HELP WOULD BE APPRECIATED.

EDWARD

Hi, Edward: Make sure your

Hi, Edward: Make sure your SFs are getting a lot of sun -- like at least 6 hours' worth a day. They also need to be moist, but in well-drained soil. Water them deeply (to encourage root growth), but not too often. And the soil needs to be fertile -- well-rotted compost mixed in works well. Monitor these things, and blooms should be on the way, at least next year anyway. Thanks for asking!

My large (3"dia.6ft)

My large (3"dia.6ft) sunflower broke off at the dirt level. Can I splint this back together, or possibly stick the raw stem deep in the ground, or would I just be wasting my time? She was just starting to flower.

If the stem is still attached

If the stem is still attached a bit it's easier to splint it back together with some tape. If it is not attached anymore the chances that it will recover are small. If you could have splinted it right away it may have had a small chance to heal. You can put the broken sunflower in a bucket of water and it may still flower for you.

We have a variety of

We have a variety of sunflowers. we are having issues with the stems snapping off at the top near the sunflower head..the size of the bloom does not seem to matter.... small ones are also snapping off...what could be causing this?

I know that there are bugs

I know that there are bugs the cut the heads off. I don't remember what they are called but you should research them. (:

i was just wondering.... i

i was just wondering.... i already harvested my sunflowers, i just want to know if they "reseed" themselves or if i need to take the stems out and reseed myself?

Thank You! :)

A sunflower will simply

A sunflower will simply reseed itself if you leave the flower head on the plant.
Or, you can collect the seeds to replant somewhere else. Let the flower head die down. When the back of the flower head turns brown, you can remove it and let it dry out.
Cover the sunflower head with a brown paper bag during this process to protect the seeds from the birds.

What month do the sunflower

What month do the sunflower seeds fall from the sunflower??

When should sunflower seeds

When should sunflower seeds be planted? i am mainly asking about the large 2-3 metre tall sunflower plants. Is July too late?

Hello, I was wondering if it

Hello,
I was wondering if it is okay to transplant sunflowers once they've bloomed. I planted them in a bad spot (right in front of my front steps) and they are huge. I want to move them but keep them alive. They are just about to bloom.

Thank you!!
Tracie

We have some volunteer

We have some volunteer sunflowers growing where our row was last year. This year we planted tomatoes in that area. The sunflowers are behind the tomato cages so we are just letting them be and grow on up. Our question is, is it safe for the sake of the sunflowers to take some of their huge bottom leaves off to make way for more light on our rapidly growing tomato plants? We have tons of tomatoes on, but they are not ripening and may be getting too much shade from the flowers. We do not want to damage the sunflowers, now that we have them.

Yes, you can remove some of

Yes, you can remove some of the sunflower leaves.

We have 2 huge sunflowers

We have 2 huge sunflowers growing right behind r tomato plants hanging over the tomatos. The tomatos will ripen slowly dont cut the sunflowers

we just got done reading

we just got done reading seedfolks and we are making a minuture garden. what should i use for the ground

We have removed the bottom

We have removed the bottom leaves up to 4 ft on our and they are 14 ft tall now they grew better when we did this anyway. We have the Russian mammoths

I have a couple large

I have a couple large sunflower heads that the petals have fallen off, and the seeds have mostly (except in the center) have turned black. But they aren't dry by a long shot, and I want to plant some of the seeds again as soon as possible to get some flowers in time for the fall season. How long should I wait? Should I separate some of the largest seeds around the edge of one of the flowers and dry them as soon as possible? Do they have to winter over?

Hello I received some Bush

Hello I received some Bush like sunflowers approx 3ft tall with many heads. Planted them in full sun and they are always drooping including leaves. Have tried to water to no avail. Did not water and drooped worse? Wonderingsince there nursery grown they may not be used to full sun or shallow roots? I am inmetro Detroit MI area.

Is there a difference between

Is there a difference between mammoth sun flowers and mammoth Russian sun flowers?

Yes there is a

Yes there is a difference...Russian mammoths grow taller than regular mammoth sunflowers

Yes there is a

Yes there is a difference...Russian mammoths grow taller than regular mammoth sunflowers

The Russian ones are very

The Russian ones are very invasive.

Just like the Russian

Just like the Russian government...very invasive ;)

Mature as in bloom?

What happens If you plant

What happens If you plant late into the season?

Hey there! Its June 21st here

Hey there! Its June 21st here in Ontario Canada.. Just wondering am I too late to plant my seeds if I plant them tomorrow?? I have several varieties of sunflowers and am hoping to get some flowers before summer is over!!

Hi Jenny, Look at your seed

Hi Jenny,
Look at your seed packages for maturity dates. That will tell you if there is time for the plants to grow and bloom before your weather turns cold. See our frost chart for first frost dates in your area.
www.almanac.com/content/frost-...

Hi Jenny. I grow sunflowers

Hi Jenny. I grow sunflowers every summer here in Richmond, Virginia USA. The heat and humidity of our summers is tough on sunflowers unlike your wonderful location of Ontario. I've always heard that you can stagger planting of sunflowers (like 3 weeks apart or so) so you have them coming up well into the Fall. I have so many seeds I'm putting in more now even though it's extremely hot (I always overseed like crazy and then thin them). I say by all means plant them. In my experience when conditions are less than ideal my sunflowers just produce flowers early but don't reach full height. It's as though they are determined to have offspring (seed heads) before their demise. So plant! Yes! You'll have more seeds to collect for next year, too. Regards, and I wish I were in Ontario. I lOVE Canada, though I've only spent time in British Columbia. –Pam