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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Most sunflowers develop pretty significant root systems, even small ones like these that mature at 1 to 2 feet, so give them about 10 inches—that a base (underground) of about one-third to one-half of the plant at maturity. It’s a rough gauge—you just don’t want the plants to be top heavy in pots that are too small.
Hey there
I'm in Southern California and I'm seeing if there is a market for 3-4 week old, single stem, pollen free, grown from seed sunflowers.
Thanks
Craig
My kindergarten's class planted sunflower seed in milk cartons. Today they sent them home from school and my rambunctious 5 year old was expected to get this poor baby plant home safely without any kind of stake or support. (Ya right). So anyways when she got home the stem is kind of squished about halfway up the stem and it no longer wants to stand at all. I used plastic straws to prop it up the best I could but I'm hoping I can still save this poor plant. My daughter and I would both be very sad to lose it. I just have no idea what the best action is. Do I continue to support it for now and wait til I can transplant it or is there some course of action that would be better. Please help.
Popsicle sticks might be a good tool for propping your sunflower. If the sunflower is planted in a small container, you need to plant it in the garden. Wait until the last frost date in your area.
https://www.almanac.com/content/frost-chart-united-states
i started my seeds inside they are king of tall can i plant them deeper than 5 inches as long as the leaves are above the soil????
We normally plant sunflowers seeds directly into the ground because sunflowers have long taproots and it’s often hard to predict when the soil is warm enough to plant.
Most seedlings do best when they’re transplanted right away but if they get too leggy, it should be OK to transplant them deeper. Bury them to about 1” below the lowest leaves. To avoid pests, you may want to keep a milk bottle around them until they’re well established and maybe circle them with slug deterrant, too.
have rescued a 4 ft tall sunflower, thick stem, leaves all almost withered and a big head on it which is totally brown. can you tell me what fertiliser I should put on it if any. I have put it in a fairly deep hole in a sheltered position formed by 2 walls and it will get plenty of afternoon sunlight. how often should I water it. the soil here is sandy. and will its leaves grow back
If the flower is brown the plant is probably not going to bloom again. Most tall sunflowers only grow one flower and after it matures you’ll see the sunflower seeds.
I had to redo a garden and added a lot of soil suitable for roses as well as compost. A selfsewn sunflower came up and reached a height of just over a metre. The flower head was as big as a small dinner plate. I have harvested this for my cockatoo but I am not sure if the plant will produce any more flowers or should I now pull it out. It doesn't have any sign of any more flowers forming and we are now coming into Autumn so it is getting cooler.
Hi Jan,
Most of the tall varieties of sunflowers have one flower per stem. Some bushier varieties have side stems and multiple flowers. It sounds like your plant is single flower. After you harvest the seeds you can pull the stem. You can save a few of the seeds to plant next spring.
