Forcing Sunflowers to Bloom in June
The blooming time for sunflowers (Helianthus) depends on their variety, the weather and the U.S. Department of Agricultural (USDA) plant hardiness zone in which the plants are located. In USDA zone 4, for example, sunflowers don't start blooming until late July; in USDA zones 8 though 10, sunflowers bloom in June and July and continue blooming into fall if sunflower seeds were planted every two weeks.
Choose a sunflower plant variety that matures in 80 days. Such varieties usually include short sunflower plants rather than the kinds that grow 12 to 15 feet tall. Some varieties take up to 120 days to mature.
Select a spot in the garden that receives a minimum of six hours of full sun per day and has mildly acidic or alkaline soil. Tall sunflower plants block sunlight from shorter sunflower plants. If you plant several kinds of sunflowers, place the tall ones on the north or east side of the shorter plants.
Plant sunflower seeds or seedlings in the selected garden spot about March 1 through 15. The soil temperature should be no colder than 55 to 60 degrees Fahrenheit for quick seed germination and growth. Space the seeds or seedlings 6 inches apart if you are in a mild climate and 2 inches apart if you are in a hot, sunny climate.
If your location's average date of the last frost is later than March 15, then start the seeds indoors four weeks before that last frost date. Plant the seedlings outdoors after March 15. If frost is forecast afterward, cover the seedlings with glass jars before sunset. Remove the jars the next morning after the frost melts.
- Water the sunflower plants consistently three weeks before and during blooming and three weeks after blooming for good seed head production.
- Use stakes to support branches heavy with blooms. Sunflowers have shallow roots and can topple over in a brisk wind while blooming and after seed heads form. Deep, regular watering encourages their roots to grow deeper into the soil, which provides support for the plants.
- Prevent bird and squirrel damage by removing the leaves closest to the maturing flower heads. Tie cheesecloth over each flower head until the seeds are ready. An option is to cut the seed heads, tie a paper bag around each seed head and hang it upside down in a dry place until the seeds easily fall out of each head when rubbed.
- Fertilize the sunflower plants only if their soil is especially poor. Fertilization promotes leaf growth rather than flowering. The fertilizer should be a balanced fertilizer, such as 10-10-10, and applied every four weeks.
Katie Jensen's first book was published in 2000. Since then she has written additional books as well as screenplays, website content and e-books. Rosehill holds a Master of Business Administration from Arizona State University. Her articles specialize in business and personal finance. Her passion includes cooking, eating and writing about food.