Centennial Ruby Hydrangea Marks Monrovia’s 100th Year
Centennial Ruby hydrangea, released in time for Monrovia’s 100th year in business, has deep red flowers that stand up to heat.
Released in celebration of Monrovia's 100th year in business, Centennial Ruby hydrangea stands out with its unusually colored, long-lasting flowers and strong performance under bigleaf hydrangea stressors like hot weather and lapses in watering.
Common name: Centennial Ruby hydrangea
Botanical name: Hydrangea macrophylla Centennial Ruby ('Hokocentennial')
Origin: Hydrangea macrophylla is native to Eastern and Southeast Asia. The cultivar Centennial Ruby was introduced by Monrovia in 2026 to mark the company's 100th anniversary. (Monrovia was founded in 1926 in Southern California by Danish immigrant Harry Rosedale. Today, the company operates nurseries in California, Oregon and Georgia, allowing for the development, testing and propagation of plants for diverse climates.)
Related: Prefer North American plants? Read about smooth hydrangea, native to the East Coast, or the Southeast's native oakleaf hydrangea.
Flowers: Appearing in midsummer, the long-lasting flowers have a dark cherry red to deep maroon color that can darken to near black. Different shades appear on the plant at one time as the individual flowers develop and mature. Although soil pH affects the color of some bigleaf hydrangeas, Centennial Ruby will retain its red hues in any soil.
Foliage: Deciduous. Broadly oval, deep green leaves with a quilted texture.
Size and habit: This is a deciduous shrub reaching three feet tall and wide with a rounded shape. This hydrangea has very strong stems to support its large flowerhead without flopping, even in the heat of summer.
Growing Centennial Ruby hydrangea
Exposure: Part sun
How to grow it: This hydrangea will perform best with filtered or part sun, evenly moist soil and an organic mulch to protect the root zone and build rich soil. That said, once it is established in the garden it can hold its stems up despite heat and lower moisture levels. Prune only to remove dead wood or spent flowers. USDA Zones 4–9.
