Sunflowers are available as perennials and annuals. The common sunflower, Helianthus annus, is an annual and grows in all zones and is an important agricultural commodity in some states. These are coarse, hairy plants with 2-3” wide flowers. Flowers range from two-colored to chestnut red or pale yellow. Another annual, ‘Sunspot’ supports heads up to 10” on 2’ high plants. Popular among the giants are ‘Mammoth Russian” and ‘Russian Giant’.
For children, annual sunflowers are easy to grow, with almost instant gratification along with a positive experience.
The Maximillian sunflower (H. maximilianii) is a North American native perennial in zones 1-24. These flowers form a clump 3’ wide and up to 10’ tall stems. Theseare topped with a spire of 3” yellow flowers. This perennial is a reliable bloomer in Colorado and is drought tolerant, once established.
Among other perennial sunflowers is the Jerusalem Artichoke (H. tuberosus), in zones 2-24. These produce bright yellow flowers, four inches across and grow easily in Colorado. Some are grown commercially and their tubers are edible, sold in markets as “sunchokes”. Tubers should be dug andreplanted every 2-3 years or the quality of the tuber will decline.
Sunflowers do best in full sun, at least six hours a day and spaced approximately 6-12” apart. Water deeply, but infrequently.
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Updated Monday, March 24, 2014