Rhododendron Calsap

Calsap Rhododendron

Calsap (Rhododendron ‘Calsap’) is an evergreen rhododendron with white flowers. Its display arrives near the middle of the rhododendron flowering season, with the exact timing influenced by local weather. Individual flowers measure about 2¾ inches across. The flower tubes widen into flared faces that display the color clearly. Wavy petal edges give the clusters additional texture. Clusters commonly carry about 18 blossoms. Contrasting dark red markings add detail within the flower faces.

The plant develops a dense crown. Its foliage is retained through winter, keeping a leafy framework between flowering seasons. It can provide a flowering focal point within a mixed shrub border or woodland-edge planting.

This cultivar tolerates sun, with light shade useful in hotter positions. Provide acidic, humus-rich soil with good drainage, maintain moisture during dry weather and keep mulch away from the stems.

Size guide
• Height: About 4 ft at 10 years; growth continues afterward
• Width: Allow for the cultivar’s natural branch spread; a verified numerical spread is not available in this reference.

Hardiness
• Approximate cold tolerance: -25°F
• USDA cold-limit equivalent: Zone 4b
This equivalence is calculated from the published temperature rating. Local conditions and summer climate also affect performance.

Best Uses
• Border
• Woodland Gardens
• Accent Plant

Plant type

Broadleaf Evergreen, Evergreen Shrub, Flowering evergreen shrub

Height

4 ft+

Width

8'

Hardiness zones

4b–8

Sunlight

Full sun to part shade

Bloom time

Spring to summer

Flower color

White

Leaf color

Yellow Green

Fall color

Green

Attracts

Butterflies

Soil

Acidic, Humus rich, Moist well-drained

Landscape use

Accent Plant, Border, Woodland Gardens

Shape

Dense

Fruit

No

Fragrant

No

Deer resistant

Yes

Salt tolerant

No

Drought tolerant

No

10-year height

4 ft