Planting, Growing, and Caring for Sunflowers
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Planting
First and foremost, find a sunny spot! Sunflowers grow best in locations with direct sunlight (6 to 8 hours per day); they require long, warm summers to flower well. Shelter from strong winds—for example, along a fence or near a building—helps as they mature. Larger varieties may become top-heavy, and a strong wind can topple them.
Choose a location with well-draining soil. The planting spot shouldn’t pool with water after it rains. Otherwise, sunflowers aren’t too picky about soil, but the soil shouldn’t be too compacted for the best results. They have long tap roots that need to stretch out; in preparing a bed, dig down or till 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.
Plant sunflowers in a spot sheltered from strong winds, perhaps along a fence or building. Larger varieties may become top-heavy, and a strong wind can be devastating.
Before choosing a planting site, decide whether or not you want to grow a sunflower tower—a fun project for kids!
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 at least 50°F (10°C).
- In the northern half of the U.S. and in Canada, this will fall between April and mid-June. In the South, this will probably occur in mid-March or early April.
- Sunflowers dislike having their roots disturbed, so we recommend direct sowing instead of transplanting.
Planting Sunflower Seeds
- Sunflowers should be planted 1 to 1½ 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 the seeds germinate. See more ways to keep birds away from your garden.
Check out this video to learn how to plant sunflowers:
Growing
- While the plant is small, water around the roots, 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.
Harvesting
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 the middle of the day may lead to flower wilting.
- Strip stems of all leaves except for those closest to the flower head. Recut bottoms of stems at a 45-degree angle.
- 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.
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!
- 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, 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.
Read our complete article on harvesting sunflower seeds here.
Recipes
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 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 add some olive oil, salt, and spices to your roasted seeds if you wish.
Or, you can also make suet cakes for the winter birds! See how to make suet.
Catherine Boeckmann
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I had several sunflowers that grew wild this year. Will they come back next year or do I need to harvest the seeds and replant in the Spring?
If they grew wildly and some of the seeds fell to the ground, it is possible that they will grow back again.
To help this happen and if all possible, check to see if there were any seeds that fell to the ground around the sunflowers or harvest some from the flower if possible.
If you do find or harvest some, I suggest digging small holes about 2-3 inches deep and about 6-9 inches apart, dropping seeds in there.
I stagger my rows and as they grow, you may find that some flowers are not as strong and keeping up. I usually end up removing about 25% of the young flowers and will either try to transplant them or grind them up and use as fertilizer for the remaining sunflowers. I believe that this helps the healthy sunflowers thrive more.
Be sure to water the young seedlings once a day and never directly on top of them. I soak around the flower bed and in the rows between where I planted and will occasionally add some sort of diluted fertilizer maybe once a week during the early stages. As the flowers mature, they won't need to be watered as frequently (unless drought) and it is suggested that mature sunflowers need watering once or twice a week with a decent soaking and again, never on or at the base of the flowers but about 12 inches away from the stems so that you are soaking the roots.
Over the course of the spring and summer, I plant and grow about 100 sunflowers and throughout the season due to culling, weather, critters, or other reasons, will lose about half of the lot. It kind of sucks losing so many but the ones that are remaining, they look great. They line my side yard along the fence and I get compliments all summer long.
On average, I usually get sunflowers 6-8 feet tall with the occasional 10+ footers. The tallest one I ever had came in at 12 feet-2 inches.
Hopefully this helps and good luck!
I have never tried to grow sunflowers but want to now. I have 5 acres, most full sun in WV. When is best time to plant? Can I do now in Sept? I have checked and cannot find answer to my question. Thank you in advance for any assistance. :)
They are an annual flower, which means that they will only last for one growing season (spring to fall). Therefore, the best time to sow sunflower seeds is in the early spring—likely around April in your area!
I have trouble with my sunflowers bending over by the flower and then falling off. What am I doing wrong? They don't look up at the sun. They just hang down. Even the stocks start to bend over.
Following . I have the same problem but the flower has not fell off yet .
Will my sunflowers re-appear next summer & should I let them die down?
Hi Gloria. Thanks for your question!
For best results, it is best to plant new sunflower seeds each spring. With the being said, you can harvest the seeds from this year’s flowers to grow next year, to eat as a snack, or leave them out for the birds and critters to enjoy.
Whatever you decide to do, you want the flowers to dry—on or off the stem—until the back of the head turns brown, the foliage yellows, the petals die, and the seeds look plump and somewhat loose. If you don’t plan on saving the seeds for yourself or your garden visitors, you can cut them down after the blooms have faded.
There is a chance a seed or two may fall to the ground at the end of the season and take next spring, but you’re better off getting a new packet of seeds in the spring and planting them.
I have a "surprise" Sunflower coming up in my front yard perennial garden! It's right in a corner front of the space. There will be nothing to tie it to or brace it if it gets tall. Should I try and move it? It's about 2' tall now! (we thought it was a weed)
so you can get some twine and you can also get a few bamboo stakes from homedepot and, then tie the twine around the stem of flower and then stick the stake in the ground diagonally and then tie the other end of twin to the bamboo. ANd it should stay. You may have to re adjust from time to time but over unless you got serious winds you should get good to go.
