Cutting off a sunflower (Helianthus spp.) Bloom can serve several functions, based on the form of sunflower you develop. With annual varieties, the only reasons to cut off the blossoms is to harvest the seeds. However, perennials can develop new blossoms if deadheaded, besides providing you.
Annual Sunflowers
Annuals sunflowers (Helianthus annuus), including the colossal varieties, do not require pruning during the growing period to promote new growth and you do not have to eliminate the flowers because whenever the blossom begins dying, it’s usually a sign the plant is dying as well. Once the blooms die, you can cut them and dry them to harvest the seeds. Pull the rest of the plant from the ground and add it.
Growing Annuals
Perennial sunflowers, like the willow-leaved sunflower (Helianthus salicifolius), which develops in U.S. Department of Agriculture plant hardiness zones 4 through 9, do not have to have their flowers eliminated, however cutting the stems of perennial sunflowers just below the dead blossoms during the growing period can help the plant refocus its energies into creating new blooms. The willow-leaved sunflower will grow as tall as 10 feet, and simply trimming off the blossoms after the plant goes dormant will not depart an attractive plant for the winter. Trim the stalks into ground level after the flowers have faded.
Collecting the Seeds
Wait until the bracts turn back of the flower head gets brownish or yellow. Both should feel dry. Cut the stem 4 to 12 inches beneath the head — the longer period gives you enough to hang it upside down to dry, if the seeds do not fall off easily. Until you cut the stem placing a paper bag on the head can help you keep any seeds which fall as the blossom moves. Examine the blossoms to check on the seeds they’re ready to harvest when they are removed by a swipe of your hand.
Cutting Live Blooms
Sunflowers create a stunning statement in your lawn, but they can do the exact same for inside your property. Instead of waiting to die, cut them about 12 inches below the bloom after the bracts form but until they open. Cutting them helps discourage wilting. Put the stems in a vase of water, changing the water daily. Use the blossoms to be supported by tall vases.