Helianthus Species, Giant Sunflower, Tall Sunflower
Helianthusgiganteus

Synonym:Helianthus alienus

Synonym:Helianthus borealis

Synonym:Helianthus subtuberosus

Synonym:Helianthus validus

Category
Edible Fruits and Nuts
Perennials

Water Requirements
Requires consistently moist soil; do not let dry out between waterings

Sun Exposure
Full Sun

Foliage
Herbaceous

Foliage Color

Height
36-48 in. (90-120 cm)

Spacing
12-15 in. (30-38 cm)

Hardiness
USDA Zone 5a: to -28.8 °C (-20 °F)
USDA Zone 5b: to -26.1 °C (-15 °F)
USDA Zone 6a: to -23.3 °C (-10 °F)
USDA Zone 6b: to -20.5 °C (-5 °F)
USDA Zone 7a: to -17.7 °C (0 °F)
USDA Zone 7b: to -14.9 °C (5 °F)
USDA Zone 8a: to -12.2 °C (10 °F)
USDA Zone 8b: to -9.4 °C (15 °F)
USDA Zone 9a: to -6.6 °C (20 °F)
USDA Zone 9b: to -3.8 °C (25 °F)
USDA Zone 10a: to -1.1 °C (30 °F)
USDA Zone 10b: to 1.7 °C (35 °F)
USDA Zone 11: above 4.5 °C (40 °F)

Where to Grow

Danger
N/A

Bloom Color
Gold (yellow-orange)
Bright Yellow

Bloom Characteristics
This plant is attractive to bees, butterflies and/or birds

Bloom Size

Bloom Time
Mid Summer

Other details

Soil pH requirements
6.1 to 6.5 (mildly acidic)
6.6 to 7.5 (neutral)
7.6 to 7.8 (mildly alkaline)

Patent Information
Non-patented

Propagation Methods
By dividing the rootball
From softwood cuttings
From seed; direct sow outdoors in fall

Seed Collecting
Allow seedheads to dry on plants; remove and collect seeds
Remove fleshy coating on seeds before storing
Properly cleaned, seed can be successfully stored