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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Anyway I could give my Seedlings enough sun? Let’s get to history: I have a very important question concerning my 4 Sunspot Sunflowers. I planted them on March 1 (about) and they have been doing pretty good. They were a great green, they got as much sun as possible, and they were growing at a great rate. The sunflowers then grew the other layer of leaves (I’m a noob, don’t expect me to know what that is called) and the lower leaves starting growing yellow and fell off because they have done their job. This was all normal. 2 days ago, they were turning a bit yellow. Today, they are extremely yellow and are losing some leaves. They are a bit wrinkly looking. The soil and water amounts are good, and the drainage system is fine, too. I think they are not getting enough sunlight. Can I do anything possible to give them more sunlight? It was supposed to be a nice spring because of global warming, but that’s conpletely the opposite, I got to do something! Is their some way I can save these 8 flowers (two in each pot) because I’ll feel dead guilty if they die. I’m doing it for a school project, and I’m getting more attached to these beauties. I’ll probably get a bad grade if they die, but I don’t care about that. I mostly care that these don’t die. If they do die, itll be all my fault and I’ll never forgive myself. Please answer ASAP! What can I do to help? Is it possible to help?! If you need them, I will post the pictures of the before sunflowers and the after sunflowers (they are still seedlings). Thanks so much, please help!
I was thinking you could make the project about " Do Sunflowers grow better in small pots or big pots; try planting some more; see how they go; (or maybe a better question : Do Sunflowers grow well in pots; plant a few in the ground to see how they sprout in comparison; thanks; aw;
"might be your type of soil; may be adding organic fertilizer might help; a bit of peat moss on the surface of the pots might help; not sure tho;; AW"
HI Blossomleaf; Can you post the before and after pictures? I can tell more when I see the Sunflowers; generally speaking; the type of sunflower you have may not too well in "pots" because sunflowers have long tap roots; do not overwater them; dry them a bit; Anne;
When to I need to plant sunflower to have them ready to use for my wedding in sept.
That’s a good question. Sunflower seed packets should say how many days they take to reach maturity. Often, it’s between 50 and 60 days from seeding. However, there could be a big window on when the flowers are truly ready to bloom. This can be affected by weather, your soil, pollination, and other factors. Therefore, we would suggest you look at staggering your seeding every couple days and perhaps plant some different varieties that have different maturity times. Just expect that nature doesn’t always agree with our plans, and hope for the best!
When is the best time of year to plant sunflowers?
You can plant sunflower seeds directly into the soil after all danger of spring frost is past. See our Frost Calculator for your local frost dates. www.almanac.com/gardening/frostdates
I planted mammoth sunflower seeds this year and they turned out very nice. There was one in particular that was huge! Looked gorgeous at full bloom and I wanted to harvest those seeds. But, after I cut it and had it in my garage, it developed a horrible smell. I presume it has been stricken by disease. I am wondering if the seeds will be any good for re-planting next year? They appear dry now, but they are more gray than black with very light striping. And a bit plump, not slender like the typical shape. Seeds from the others I tried to dry look normal and just like the ones from my original package. Thanks!
We've planted some sunflower seeds for the first time this year an had a huge sunflower stalk with 14 flowers on it, but some are now dying, please can you tell us how to get the seeds out ready for next year?
