Western Hop-hornbeam, Knowlton's Hophornbeam, Wooly Hornbeam, Ironwood
Ostryaknowltonii

Family: Betulaceae (beh-tyoo-LAY-see-ee)
Genus: Ostrya (OSS-tree-uh)
Species: knowltonii (nohl-TOH-nee-eye)

Category
Trees

Water Requirements
Drought-tolerant; suitable for xeriscaping
Average Water Needs; Water regularly; do not overwater

Sun Exposure
Sun to Partial Shade

Foliage
Grown for foliage
Deciduous

Foliage Color

Height
20-30 ft. (6-9 m)
30-40 ft. (9-12 m)

Spacing
20-30 ft. (6-9 m)

Hardiness
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)

Where to Grow

Danger
Handling plant may cause skin irritation or allergic reaction

Bloom Color
Red
Brown/Bronze

Bloom Characteristics

Bloom Size

Bloom Time
Mid Spring

Other details

Soil pH requirements
6.6 to 7.5 (neutral)
7.6 to 7.8 (mildly alkaline)
7.9 to 8.5 (alkaline)

Patent Information

Propagation Methods

Seed Collecting