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Catawba Rhododendron, Iron Clad Rhododendron
Rhododendron catawbiense 'Grandiflorum'

Family: Ericaceae (er-ek-AY-see-ee) (Info)
Genus: Rhododendron (roh-do-DEN-dron) (Info)
Species: catawbiense (ka-taw-bee-EN-see) (Info)
Cultivar: Grandiflorum
» View all varieties of Azaleas and Rhododendrons




10-12 ft. (3-3.6 m)

12-15 ft. (3.6-4.7 m)


8-10 ft. (2.4-3 m)


USDA Zone 4b: to -31.6 C (-25 F)

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)

Sun Exposure:

Sun to Partial Shade

Light Shade


All parts of plant are poisonous if ingested

Bloom Color:


Bloom Time:

Late Spring/Early Summer




Other details:

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

Average Water Needs; Water regularly; do not overwater

Provides winter interest

Patent Information:

Unknown - Tell us

Seed Collecting:

N/A: plant does not set seed, flowers are sterile, or plants will not come true from seed


This plant has been said to grow in the following regions:

Chicago, Illinois

Shawnee Mission, Kansas

Mechanicsville, Maryland

Halifax, Massachusetts

Oyster Bay, New York

Murrysville, Pennsylvania

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Gardeners' Notes:


On Jan 13, 2014, SoooSirius from Municipality of Murrysville, PA wrote:

These are VERY long-lived shrubs that can take abuse and severe pruning and bounce right back. The ones surrounding my house are over 40 years old, transplanted from someone's grandma's place. I have sawed them back to 3 ft. twice now since we've been here. These get big. They are in scale to a large Victorian or Georgian style house. (Think 15 ft tall with an equal spread.) They can cover themselves with bloom and are a showstopper when they do. Otherwise they're just dark green. They do have low branches that will root and can be transplanted, and so never seem to have that empty space below that needs to be filled with other plants.
They bloom reliably, deer don't bother them unless they're desperate.