How to Care for Sunflowers & Harvest Seeds

Although sunflowers are native to the Great Plains of the United States, European settlers took them back to their homeland to grow and cultivate for themselves. In fact, today, sunflowers are a major agricultural crop in Russia, notes Burpee.com.

As the name implies, sunflowers love the sun, and will track the sun's path across the sky throughout the day. Interestingly, sunflowers emit a chemical that can harm other plants, so you’ll need to plant them in a dedicated location to avoid endangering other plant growth.

How to Plant

Just like in real estate, you should be thinking "location, location, location" when deciding where to plant your sunflowers outdoors. They thrive in direct sunlight, but they also tend to take up a lot of space, especially if you choose to plant one of the larger varieties. And since sunflower heads tend to track the sun, keep in mind that the bloom will face the sun, and not necessarily your window or front yard from the street.

1. Create a shallow trench one to two inches deep in slightly acidic soil (between 6 to 7.5 pH).
2. Space seeds about six inches apart and cover them with surrounding soil. Space seeds father apart if planting larger varieties, to accomodate room between the large flower heads.
3. Water thoroughly, but do not waterlog the seeds. Expect sprouting in about 7 to 10 days.

If you want contiuous blooms throught the season, wait two to three weeks and create another shallow row for planting. Space rows about two to three feet apart.

Consider planting two (or more) different varieties of sunflowers in rows in front of each other, with the smallest variety planted in front of the larger variey for a "stair-step" look of blooms.

General Care Tips

Although you may begin by planting sunflowers indoors or outdoors, most gardeners plant the seeds directly in the soil so they don't have to transplant them later. Wait until all threat of frost is gone, and until the soil reaches 55-60 degrees for optimum results.

Sunflowers are fairly drought-hardy, however they do require the most amount of water at time of initial planting, and also about 20 days before and after blooming.

Consider supporting larger (and taller) sunflowers with a stake to keep their stem from stressing and breaking. Burpee suggests staking blooms over three feet tall or those that are multi-branched. Use soft cloth or to keep the sunflower loosely supported.

Considerations

The variety of sunflower you select will likely depend upon your intentions for the flower. So before just grabbing a packet from the local nursery or grocery store, consider where you plan on planting the sunflower, and if you want to just enjoy the beauty of the bloom or harvest the bloom for seeds.

For example, a large sunflower would be impractical in a small container garden. Similarly, if you plan on harvesting the seeds a dwarf variety won't give you enough of a seed crop. If you live in USDA zone 3, consider planning varieties such as the Jerusalem artichoke, or the Mexican sunflower, which can tolerate colder outdoor temperatures.

Pay close attention to the packing for recommended usage and projected size of the plant. See the table below for a quick reference guide on types and uses.

Picking the Right Variety for Your Needs

How to Harvest Seeds

If critters don’t get to your seeds before you, there are a few different ways you can harvest the seeds yourself. Check the flower head for signs indicating the bloom is ripe for harvest.

1. Inspect the backside of the bloom. If it has turned from a green to a yellowish-brownish color, the head is ready for harvest.
2. Use sterilized snippers to cut off the bloom and about one foot of the stem.
3. Hang the stem upside-down in a warm, dry, aired location for a few weeks.
4. Remove completely dried seeds by brushing them off with your fingers or a stiff brush.
5. Collect the seeds on baking sheet, and allow them to dry for a few more days.
6. Store seeds in am airtight container or in the refrigerator.

Keep critters such as deer, birds and squirrels at bay by protecting your bloom if it id not quite ready for harvest. Gently attach either a large sheet of cheese cloth, or a large paper bag to the stem. These methods preserve the seeds on the stem, while allowing the bloom to wither away still attached to the stalk.

How to Roast Sunflower Seeds

Roasting sunflower seeds yourself is fairly simple, and also allows you to control the saltiness of your snack. Adjust the recipe below to suit your preferences, you can omit or even lessen the salt amounts.

1. Place up to ¼ cup salt per 1 quart of water on the stovetop.
2. Rinse sunflower seeds with fresh water to remove errant debris.
3. Add rinsed seeds to salt water and cook them for 15 to 20 minutes. The heat should be in the middle of a simmer and a boil.
4. Meanwhile, preheat the oven to 400 degrees F.
5. Drain seeds in a colander, and spread in a single layer of a sheet pan.
6. Roast sunflower seeds for 10 minutes. Then start checking seeds for doneness. Seeds should look light brown, be slightly swollen and start to crack. Stir seeds on sheet with a wooden spoon, and continue cooking, checking seeds for doneness every two to four minutes. Keep an eye on the seeds as they can char quickly!
7. Remove seeds from the oven and allow them to cool.

Store roasted seeds in an airtight container.

Pests

Sunflowers are relatively pest-free. In fact, the best way to take care of your sunflower is to maintain your garden’s cleanliness with weeding and proper watering techniques. But when insects do invade your flowers, you’ll need to identify the pest correctly in order to treat the issue accurately.

Sunflower beetles often feed on the leaf. Although unsightly, the main issue would be when the beetles consume the young true leaves of the plant.

Cutworms can also eat the leaves of young plants, however it is not normally an issue unless there is a heavy infestation.

Sunflower moths and grasshoppers are the most dangerous to sunflowers by eating on foliage and destroying the plant, but again, this is normally only when there is a large infestation.

Although sunflowers rarely suffer from disease, the most common issue with is actually stem rot. Take care to not overwater the plant, and avoid wetting the bloom when possible.

Helpful Resources

Questions & Answers

Question: What if I harvest my sunflower seeds too soon and the seeds are still white?

Answer: It is best to wait until the seeds are dark black and you can loosen them slightly from the head. However, you may still be able to salvage the seeds.

If the sunflower head is still intact with seeds, try placing it in a brown paper bag, and hanging it up in a warm, well-ventilated area for a few weeks. Ideally, there would be several inches of stem connected to the head so you could hang it upside down. The warmth and time should allow the seeds to dry enough to be eaten.

If nothing else, set the head outside so that the birds and other yard critters might have something to munch on.

Question: How should I store seeds for planting in the spring?

Answer: Great question! Store dry seeds in a small, labeled envelope and place it in a sealed, freezer-safe bag in your freezer. Don't worry that the seeds will be damaged from the temperature--freezers are ideal because they have low humidity. Allow seeds to come to room temperature before planting them in the soil. Seeds kept in a freezer should be good for about three years.

Diane Lockridge (author) from Atlanta, GA on August 24, 2018:

@Blaine it sounds like you need to support the stem of the sunflower with a stake. Consider putting a bamboo shoot, or a metal rod near the base of the plant, then gently tying the stem to the stake with raffia or twine. Hopefully the additional support will help your sunflower look (and feel) better!

Blaine Miller on August 23, 2018:

First sunflower we ever played. Grew a little slow compared to neighbors. Got over 7.5’ with huge head. Had 3 grey days, wind, and rain. Head now almost looking at ground. I tried to prop up. Is all ok? Should I just leave it alone?