Mountain Hydrangea 'Kurenai': Deep Red Serrata for Acidic Soils

Mountain Hydrangea 'Kurenai': Crimson Beauty from the Japanese Alps

Hydrangea serrata 'Kurenai' (Japanese for "crimson" or "deep red") is a remarkable mountain hydrangea cultivar that produces intensely red lacecap flowers in acidic soil—a rare color breakthrough for H. serrata, which typically ranges from blue to pink. This cultivar brings true crimson to the serrata palette.

True Red in a Blue Species

H. serrata is genetically predisposed to blue/pink coloration (like macrophylla), but deep red is unusual. 'Kurenai' achieves a saturated crimson-red in strongly acidic soil (pH 5.0–5.5)—the same conditions that produce blue in most cultivars. The lacecap inflorescences are 3–4 inches across, with a central dome of tiny fertile flowers in matching crimson, surrounded by a ring of large, cupped sterile florets in the same intense hue.

The plant forms a graceful mound 2–3 feet tall and wide, with the slender stems and finely serrated leaves of the species. Superior cold hardiness (USDA zones 5–9).

Japanese Breeding Achievement

'Kurenai' represents advanced Japanese selection for novel colors in H. serrata. Culture: bright shade or morning sun, moist acidic soil (essential for red color), cooler nights preferred. Blooms on old wood. The red color is stable in acidic conditions but shifts to purple-pink in neutral/alkaline soil.

Taxonomic Profile

• Family: Hydrangeaceae
• Genus: Hydrangea
• Species: serrata
• Cultivar: 'Kurenai'

Red Seratta Pioneer

'Kurenai' opens new design possibilities for mountain hydrangeas. Its crimson lacecaps pair beautifully with gold foliage (Hakonechloa 'All Gold'), purple heucheras, and dark green backgrounds. A breakthrough cultivar for serrata enthusiasts and red-flower lovers alike.