Not only are sunflowers beautiful summer plants, they’re also resilient ones that love direct sun and hot days. Plus, their large heads produce seeds that are healthy and snackable, making sunflowers a decorative and edible plant for your seasonal garden. Here’s how to grow happy and healthy sunflowers, and how to harvest those seeds.
How to plant sunflowers
Sunflowers are obviously sun-loving plants and they don’t do well in the cold, so you’ll want to start prepping the soil for planting well after the temperature has stayed above 50 degrees during both the day and night. (Planting late May early June is best for outdoor flowers).
Sunflower roots need substantial space to grow big and tall, so plant seeds directly outside rather than transplanting them from a pot. Because they grow so quickly, starting in a pot could stunt the flower’s growth before making it to the garden.
You’ll also want to cultivate the soil for optimal germination before planting seeds. SFGate Home Guides recommends tilling the soil about 12 inches deep and mixing compost or “well-rotted manure” on the top four inches to promote a fertile growing environment.
Once the soil is ready for the seeds, plant them at least six inches apart and staggered for space. Put five to six seeds inside of a one-inch deep hole and cover them with soil. Keep the soil moist for faster germination. Renee’s Garden suggests putting some sort of barrier around the seedlings to prevent slugs and bugs from eating the new growth. You can use things like vinegar, coffee, and crushed eggshells to repel bugs as your flowers grow.
Thin your sunflowers for optimal growth
The process of thinning plants involves picking seedlings that are close together to allow more room for one sprout’s growth. You plant several to ensure germination for sunflowers, but as soon as the seeds sprout to three inches, cut the excess for the strongest to survive. Renee’s Garden suggests cutting down to two plants when they reach a foot, then selecting the healthiest one after they grow to two feet and removing the other:
The point of this gradual thinning method is to ensure that you’re left with at least one good seedling in the event that predators damage any of the others. Remember, it’s critical to thin back to the best single seedling if you’re going for giant sunflowers. Leaving even several seedlings growing too close together will keep you from growing a giant in your garden.
How to harvest your own sunflower seeds
When the flowers have grown to their full potential, you’ll start to see seeds filling the middle section of the sunflower head, but choosing the right time to harvest these seeds isn’t so easy a task. Kellogg’s gardening site gives a few signs to look out for that your seeds are ready to be collected.
- Harvest when seeds are plump and developed.
- Harvest when flower petals begin to dry out and fall off.
- Harvest when the back of [the] flower turns from green to yellow (if you are cutting the stem off to dry).
- Harvest when the back of the flower is brown (if you are letting seeds dry with the stem intact).
When you start to see the seeds develop, place a netting or paper bag over the flower’s head to catch any seeds that fall, and to protect them from birds and insects. You can then use your fingers to loosen seeds into the bag or net. If the plant is ready, you can also collect seeds by cutting the stem four inches from the head, removing the flower completely. Hang the flower head upside down in a bag or net to let the seeds mature and, with your fingers, rub the seeds until they fall.
After harvesting, wash the seeds and spread them out on a towel to dry before eating. Fresh seeds will last you anywhere from three to four months raw and up to five months roasted. Frozen seeds will last up to a year.