What Is the Average Height for a Sunflower to Bloom?

Tall Sunflowers

• The tallest sunflowers are called "giant" cultivars for obvious reasons. These can grow up to 14 feet tall and often require support, such as staking. The largest of these cultivars is "Cyclops," which can reach 15 feet. The shortest is "Giganteus" at around 10 feet tall. This means that the average height for a giant sunflower to bloom is 12.5 feet.

Medium Sunflowers

• Medium-sized sunflowers are referred to as "semi-dwarf" cultivars. They range in size from 3 to 8 feet tall, making the average blooming height 5.5 feet. Some of the smaller cultivars include "Tangina," which has flowers about 4 inches in diameter, and "Jade," which has unusual flowers of cream and lime. The largest semi-dwarf cultivars are "Cappucinno," with deep burgundy flowers, and "Sungold," which has bright yellow blooms.

Small Sunflowers

• Small sunflowers are often grown in cutting gardens and used in flower arrangements. They range in height from 1 to 3 feet and are dwarf cultivars. The smallest is "Elf," which is yellow. Others include "Sunset" and "Sunspot," the latter of which has 10-inch, yellow flowers on 2-foot stems. The average height for a dwarf sunflower to bloom is at 2 feet tall.

Considerations

• All of the listed cultivars of sunflowers bloom at that height only when cared for properly. Adverse environmental conditions, including diseases and insect pests, can negatively affect growth and flowering. Sunflowers need full sunlight to bloom well. Once the bud appears, it will turn to follow the sun until it fully flowers. Aphids are a particular pest of sunflowers and severe infestations can stunt a sunflower's growth. If you see aphids on your sunflowers, spray them with an insecticide.