What Should You Do With Sunflowers After They Bloom?

The yellow faces of sunflowers (Helianthus spp.) symbolize the bright, sunny days of summer. Different types of the sun-loving, thirsty flowers grow in both annual and perennial gardens. Use them for decorative purposes, or harvest the seeds as part of a summer garden crop.

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What Should You Do With Sunflowers After They Bloom

Varieties of Sunflowers

Sunflowers grow as annuals or perennials. Annual flowers can have either small or large seeds. They bloom in late spring in the year they're planted and have stringy roots. Perennial versions are generally smaller than annuals and grow in early spring as clumps of flowers. They have small seeds and roots grouped as knotty rhizomes. Perennial sunflowers grow throughout U.S. Department of Agriculture plant hardiness zones 3 to 9. Both types of sunflowers produce edible seeds, although the largest varieties have the best seeds for snacking.

Two examples of these are the cultivars "Maximilian" and "Mammoth." The perennial "Maximilian" (Helianthus maximiliani) is a tall, native prairie sunflower that blooms from August through November. It grows in USDA zones 4 through 9. "Mammoth" (Helianthus annuus "Mammoth") blooms over the summer with traditional bright yellow heads up to 1 foot across. Growing up to 12 feet tall, these fast and easy-to-grow flowers provide plentiful seeds at harvest time.

Decorative Flowers

Cut sunflowers serve a sunny decorative purpose in flower arrangements. Annual flower heads are very heavy and can droop and break without support. Slide on plastic stem supports, or tie the upper stems to a wooden dowel to prevent breakage. Immediately place the freshly cut stems in a vase of water. Sunflowers can last a week if you keep them well hydrated. Flowers you chose not to cut should be supported with garden stakes and ties to prevent wind damage.

Harvesting Seeds

While sunflowers are beautiful to look at, their seeds are also a valuable crop. To harvest the seeds for use, wait until the backs of the flower heads turn yellow, dry out and turn brown. This usually happens 30 to 45 days after blooming. Once the seeds dry completely, cut the head off about 4 inches down the stem. Remove the seeds using your fingers or a fork.

Pest Protection

When you dry sunflowers outside, they can become a temptation for outdoor animals like birds and squirrels. To protect the heads, cover them with a light, breathable fabric like cheesecloth, and secure it with a twist-tie below the head. Alternatively, you can cut the flower head early along with at least 2 feet of stem and bring them inside to dry. Hang the heads upside down in an area where pets or indoor pests can't get to them.

Seed Preparations

With many cultivars of sunflowers available, there are many sizes of seeds. Smaller flowers with small solid black seeds are generally used for animal and bird feed or by industry for making oils. Larger, striped seeds are best for human snacking. To prepare these larger seeds to eat, soak them overnight in 1 gallon of water mixed with 1 cup of salt. Dry them in an oven set to 250 degrees Fahrenheit for four to five hours. Store the salted and dried seeds in an airtight container.

Feeding Animals

Share your bounty with furry or feathered friends in your neighborhood. If you want to let the birds eat the seeds, you can leave the sunflower heads on the plants. The birds, squirrels and other animals can find the seeds easily. Want to store up a winter harvest for the animals? Harvest the seeds as you would for your own consumption. You can put the seeds out for the animals a little at a time during the winter.