Did you know that each sunflower can hold as many as 1,400 seeds? And since these majestic flowers are so easy to cultivate, why not grow some in your garden next year for your own fresh harvest of delicious seeds.
When the sunflower seeds are ready, they will be at the mercy of the birds who also want to enjoy them. So, If you want to nibble on the delicious kernels yourself or store them for the winter it’s important to know when to harvest your sunflower seeds.
Most sunflower seeds will be ready to harvest about 110 and 135 days after germination. Sunflower seeds are ripe when the petals have fallen, the flower heads have turned brown and have begun to droop.
Once the yellow leaves have said goodbye, remove the entire head and bring it indoors to finish drying. Alternatively, you can cut the head early if frost is in the air and the seeds will finish maturing indoors.
If you grow sunflowers, you can take your own seeds for the next growing season. You can also harvest seeds to eat or to give them to the birds.
A Flower Full Of Seeds
A sunflower is not actually a single flower, but is a composite of over a thousand small flowers, or florets.
The outermost mini flowers are called ray florets which produce the tell-tale yellow (or orange or red) petals of the sunflower.
Ray florets do not produce seeds, and instead their purpose purpose is to attract pollinators to the sunflower.
The middle of the sunflower is a collection of up to 1,400 individual disc florets, each of which is a complete flower consisting of male and female parts.
The bees and other insects are attracted by the outer petals and they pollinate the disc florets. Each successfully pollinated disc floret will produce a single sunflower seed.
Choose The Right Variety
For over 5,000 years, sunflowers have been cultivated for food and the seeds were ground into flour or pressed into oil.
Many modern sunflower varieties, however, are hybridizations that produce large and beautiful heads with little-to-no seeds. Be sure to research each variety carefully to ensure it will produce edible seeds.
When selecting a sunflower variety to grow for seeds, another factor to consider is single stem versus branching types.
Single stem varieties grow straight, tall stalks with a single flower at the top. They have the advantage of more uniform and predictable bloom time and they can be grown closer together. Single stem sunflowers often mature very quickly to produce edible seeds.
Our ancient ancestors grew branching varieties, which produce a cluster of flowers on a single plant. These heads are usually smaller and the plants are more compact so they need to be grown farther apart.
While branching varieties produce more flowers per plant, the flowers will not all bloom at the same time, making harvesting a little more tricky.
Branching types often come in a plethora of colors, offering you an aesthetic as well as an edible aspect to your garden.
Here are a few varieties of seed-bearing sunflowers to get you started:
When To Harvest Sunflower Seeds
Most sunflower varieties will list a “days to maturity” which refers to when the plant will start blooming. The sunflower seeds will be mature 30 to 45 days after the flowers have bloomed.
On average, most sunflower seeds will be ready to harvest 110 to 135 days after germination.
As your sunflowers mature, here are a few ways to tell that the seeds are ready for harvest:
Soft, milky white seeds are not mature, so leave the seeds a little longer and check them again.
How To Harvest Sunflower Seeds
The easiest method for harvesting sunflower seeds is to let them completely dry on the plant. Once the back of the flower heads turns pale yellow and the edges begin to turn brown, cut the stem about 2cm to 3cm (1inch) below the flower. Then rub off the surface of the flower with your palm to loosen the seeds and then blow lightly on everything to separate the seeds from any small waste.
The disadvantage of this is that mold can form and birds are already picking away numerous seeds. To protect the ripe sunflower seeds from the weather or birds, cover your flower heads with a paper bag. Simply place the bag over the flower and tie it to the stem. If the bag gets wet in the rain, simply replace it.
With a paper bag over the flower, you make harvesting easier. If the sunflower seeds come loose, they fall directly into the bag and are not lost.
If your season is not long enough, the sunflower heads can be cut and brought indoors to finish maturing. Once the outer seeds have matured, cut the flower head with 30cm (1ft) of stalk still attached and hang the flowers upside down in a warm, dry location until all the seeds have matured.
Once all the seeds are mature, leave the cut flower head in a warm, dry place with good air circulation and allow the seeds to completely dry for a few more weeks.
After drying, some of the kernels fall out themselves, to loosen the rest, remove the seeds by rubbing two heads together or with a stiff brush. Particularly stubborn seeds can be dislodged with a dull tool.
You can also place a coarse screen over top of a bucket and rub the flower head overtop so the seeds fall into the bucket. Then collect the seeds, wash them thoroughly with cold water and then dry them.
Allow the sunflower seeds to dry for a few days spread out flat, and stir them occasionally to ensure the whole batch dries evenly.
Storing Sunflower Seeds
Store sunflower seeds in glass, ceramic containers or paper bag in a dry place until next spring. Sunflowers are known to absorb toxins out of soil, and they were even planted around Chernobyl to help clean up the radioactive contamination. The seeds can also absorb chemicals from containers they are stored in so avoid plastic containers if possible.
They can be stored hulled, or unhulled, depending on your intended use. Keep them in an airtight container. They will keep for 2 to 3 months in a cool and dry location, such as in your kitchen cupboard.
Refrigeration or freezing will prolong the shelf life and they will keep this way for up to a year.
How To Remove The Shell Of Sunflower Seeds At Home
To quickly remove the husk from sunflower seeds, follow these steps below:
Tips For Growing Sunflowers For Seeds
Sunflowers grown for seeds can be grown exactly the same as if you were just growing them for the flowers. However, here are a few tips that will make your sunflowers produce bigger and better seeds.
1: Start them early
Since your sunflowers need at least 110 days for the seeds to mature, make sure you start them early enough in the year so they have time to mature before fall as the adult plants will not survive a killing frost.
Sunflowers can be started as much as 4 weeks before your last frost date.
For most single stem sunflower varieties, space the seeds 30cm (12 inches) apart, while branching varieties or very large giants should be spaced 45cm (18 inches).
Keep your rows 60cm to 90cm (2-3 ft) apart. This will ensure the plants have enough space to fully mature.
3: Avoid fertilizing
Our sunflowers have always grown well without any fertilizing (though they greatly benefit from compost). Over-fertilizing can result in unnaturally fast stalk growth that can cause the stems to break under the weight of the full seed head.
4: Add Borax
An application of 1 tsp of Borax in 1½ cups of water can be applied to a 5m (15ft) row to aid seed development.
5: Stake tall varieties
Don’t forget to stake tall varieties to keep them from falling over as the flower head matures.
6: Protect from hungry wildlife
If you are growing sunflower seeds for yourself or your family, you need to make sure the birds and other hungry animals don’t get them first.
Keep deer from eating your sunflowers by constructing a sturdy fence around your plot.
Birds and squirrels can be kept at bay by motion sensor animal deterrents or by wrapping the flower heads in row cover cloth, cheesecloth or paper bags. Alternatively, consider planting lots of sunflowers so there is enough for the birds and still enough left for you.
Some moths also enjoy snacking on sunflowers and the best response is to handpick any worms or eggs from the plants when you see them.
Sunflower seeds are a healthy and nutritious addition to your diet, and what better way to have some than to grow your own.
As well as using them for a snack or pressed for oil, open pollinated and heirloom varieties can also be saved and planted in next year’s garden.
These tall, majestic flowers are easy to grow and even if your seeds fail to develop, they will add beauty and magnificence to your home and garden.
Amber Noyes was born and raised in a suburban California town, San Mateo. She holds a master’s degree in horticulture from the University of California as well as a BS in Biology from the University of San Francisco. With experience working on an organic farm, water conservation research, farmers’ markets, and plant nursery, she understands what makes plants thrive and how we can better understand the connection between microclimate and plant health. When she’s not on the land, Amber loves informing people of new ideas/things related to gardening, especially organic gardening, houseplants, and growing plants in a small space.