How to Harvest Sunflower Seeds

Tall, bright and elegant sunflowers are a staple plant in many gardens and allotments. Everyone from young children to experienced gardeners enjoy growing these majestic flowers during the summer months. However, what many people don’t realise is that the attraction need not end as the flowers fade.

As the blooms fade, the central part of the flower produces masses of seed. Some people, myself included, like to leave these in place for birds and wildlife to harvest. But if you are partial to sunflower seeds you can also harvest them yourself.

If you want to learn how to harvest sunflower seeds, this is the guide for you. Our how to harvest sunflower seeds guide will take you through everything that you need to know.

A popular part of the summer garden, knowing how to harvest sunflower seeds enables you to get even more enjoyment from these colorful plants.

What is a Sunflower?

Before we discuss how to harvest sunflower seeds, I will quickly explain what these plants are. Officially known as Helianthus annuus, these popular plants are members of the Asteraceae family. Other members of the Asteraceae family include daisies and osteospermum.

Easily identifiable thanks to its large, open flower, the flower’s central disk is actually made up of lots of small inflorescences. These are surrounded by large, usually yellow, petals. You can also find varieties that flower in shades of orange, white, red and deep purple.

Each inflorescence or floret is able to self pollinate, producing one kernel or seed which is contained in the outer hull. Depending on the cultivar the seed can be striped or black.

When to Harvest

Before we discuss how to harvest sunflower seeds, we will first explain when is the best time to start harvesting.

One of the best plants to start from seed, knowing when to begin harvesting is an important part of knowing how to harvest sunflower seeds. Start too early and the seed will be small and disappointing. Wait too long and the visiting wildlife may beat you to it.

Kernels can ripen at any time from July to October. It all depends on where you are growing, which variety you have planted and when the plants were started. In general, the earlier you start your plants, the sooner they are ready for harvest.

As the flowers fade, the petals turn brown and start to shrivel or dry out. Meanwhile, in the center of the flower, kernels start to form.

Continue to pay close attention to the central disk. You will notice the tiny petals drying out. Lightly scraping your hand across them dislodges the petals from the disk. This exposes the tightly packed kernels.

The kernels are ripe and ready for harvest when the calyx, back of the flower head, turns yellow-brown and the outer petals fall from the plant.

As the flower fades, the kernels form. 

How to Harvest Sunflower Seeds

If you choose to let the kernels mature on the stalk there is a danger that they will ripen and fall from the plant. Either setting seed where they fall or being spread around the wider area by visiting birds and squirrels. This can result in lots of surprise flowers next year. In fact, did you know that planting some Helianthus annuus is one of the best options for attracting birds to your garden?

If you don’t mind the plants being spread around your garden then allow the heads to dry out on the stalk. If you want to prevent this then you will need to cut the flower head from the plant.

To know when to cut the flower head, watch the back of the flower head, calyx closely. When it turns from its original green to a yellow-brown shade, cut the head along with 6 to 8 inches of stem. You will need to use a sharp knife or pruning shears. Helianthus annuus have notoriously thick stems. These can be difficult to cut through if your tools aren’t sharp enough. A whetstone is a great way to sharpen garden knives and tools.

Cut away any leaves that are still attached to the stem. This removes any pests that may be hiding in the foliage. If you are drying more than one cut stem, tie a few, no more than 4, together with a bit of garden string, such as Jute Twine.

Hang the stems upside down, with the heads facing down to the floor, in a shady or partial sun position that is dry and well ventilated. A shed is ideal. When the heads turn brown you can begin to harvest the seeds.

As the heads dry you may want to place a sheet of paper under the flower heads to catch any kernels that drop. Don’t use a plastic sheet, this can lead to a build up of moisture and may cause kernels to turn mouldy.

How to Harvest Sunflower Seeds by Drying the Heads on the Stem

If you don’t mind some stray seed being spread around the garden, allow the stems to remain in place.

Regularly check the back of the heads. When they turn brown, turn your attention to the kernels. Mature kernels are plump. If one or two have fallen out it means they are ripe and ready to harvest. To prevent wildlife from taking the seed as they mature, try tying a paper bag around the flower head.

When learning how to harvest sunflower seeds you may need to protect the drying kernels from visiting wildlife. 

When the seed is ripe, cut the stem about 7 inches from the flower head.

You will notice a protective layer of pollen over the kernels. This protective layer resembles small bits of fluffy debris or green-yellow buds. Its presence helps to protect the seeds as they form.

With a knife or your hand gently scrape away the dry remnants of the inflorescence petals from the center disk to reveal the kernels.

Separating the Kernels from the Flower Head

The next step in learning how to harvest sunflower seeds is to learn how to separate the kernels from the flower head. There are two ways to do this. Whichever method you follow, you will need a bucket or suitable large container to catch the kernels as they fall.

The first method is to simply use your thumbs to rub the kernels away from the flower head. Allow the container to catch them as they fall. To make it easier cut or snap the flower head into smaller, manageable pieces.

Alternatively take two ripe heads or two pieces of the same flower head that are roughly the same size and gently rub them together. Again, do this over the container so that the kernels are caught as they fall.

After drying, you need to remove the mature seed from the flower head. 

Handling Sunflower Seeds

A vital part of learning how to harvest sunflower seeds is knowing how to handle, prepare and store the seed.

If you want to save some seed for sowing next year, or to feed to the birds, the seed can be stored in an airtight jar, such as a Mason Jar, or an envelope in a cool, dry place until you’re ready to use them. Remember to label and date your envelopes and jars. As it ages a seed loses its viability.

Some people like to eat the seed raw, cracking the shells with their teeth. You can also roast the seed. This makes them easier to crack open. Roasting also gives the seed a richer flavor.

How to Roast

If you are learning how to harvest sunflower seeds so that you can enjoy a homegrown roasted snack, preheat the oven to 400°F. Spread the seed out in a single, flat layer on a baking tray or ungreased roasting pan. Roast for 5 to 8 minutes.

When dry the hulls can be easily cracked open. You may need to return them to the oven for a few more minutes until they are fully dry.

If you prefer salted seeds, add 2 to 4 tablespoons of salt and 1 cup of seed to a quart of boiling water. Simmer for around 15 minutes. Drain the water away and dry the kernels on a baking tray before roasting in the oven as described above.

Finally, if you want to roast the kernels without their shells, you will need to shell each kernel before roasting. This is easier than it sounds. Place half a cup of kernels in a plastic bag and seal it. Lay the bag down so that the kernels are flat.

Use a rolling pin to crack the shells open. After cracking all the hulls, empty the bag into a bowl of water. The broken hulls float to the top, the kernels which are heavier sink to the bottom.

Remove the shells from the water, a slotted spoon is useful here. Drain the water and allow the seed to dry before roasting. Roast the shelled seed for 8 to 10 minutes at 350 °F. Remember to turn them halfway through the process.

The seed is protected by a shell. To enjoy the seed you will need to remove the shell. 

You can store raw, unshelled seeds in a cupboard or the pantry for 2 to 3 months. They keep in a fridge or freezer for up to 12 months. Roasted and unshelled, the seed can be stored for 4 to 5 months in a cupboard or up to a year in a fridge or freezer.

One of the easiest flowers to grow, Helianthus annuus are a popular member of the summer garden. Their tall bright blooms bring color and pollinators to the garden. Knowing how to harvest sunflower seeds is beneficial for a number of reasons. It enables you to save seed for sowing next year, feed the visiting garden birds or even keep for yourself as a quick snack.