Schweinitz's Sunflower

• Schweinitz' s sunflower, Helianthus schweinitzii, has hairy, purple stems that grow up to 10 feet tall. The flowers are yellow and have the same shape as common sunflowers, but the blooms are slightly smaller in size. The center of Schweinitz's sunflower is yellow-green in color, unlike the brown centers of common sunflower. The plant grows from tubers in March and April, and flowers in September. Plant Schweinitz's sunflower in full sunlight to partial shade.
  
  

False Sunflower

• Ox eye or false sunflower, Heliopsis helianthoides "Summer Nights," has reddish-purple stems and leaves with a yellowish cast to them. The flowers have more of an orange tint to them than those produced by the common sunflower, and the center "eye" is orange-red in color. The flowers bloom from June to August. Plant false sunflower in moist, well-drained soil where it will receive full sunlight. Ox eye sunflower grows 3 to 6 feet tall.
  
  

Tall Sunflower

• Tall sunflower, Helianthus giganteus, has reddish-purple stems that grow up to 10 feet tall. The foliage is traditional green in color, and the blooms have large brown eyes with bright yellow petals. Native to the United States, tall sunflower grows without cultivation in USDA hardiness zones 3 through 8. The flowers bloom from August to October in moist, well-drained soil. Plant tall sunflower in a site where it will receive full sunlight.
  
  

Hairy Sunflower

• Hairy sunflower, Helianthus hirsutus, has central stems that are light purple in color. The flower gets its name from these stems, which are covered in fine hairs. Hairy sunflower grows up to 5 feet tall with medium to pale green leaves. The small, central eyes are yellow-green in color and the petals are bright yellow. Hairy sunflower grows in full to partial sunlight in a wide range of soil types, from heavy clay to light sand. Hairy sunflower is so easy to grow, it may be classified as a weed because of its invasive nature. The flower grows wild in the United States in fields, woodlands and sites were soil quality is either poor or rich.