Hydrangea petiolaris (eastern Asia)
(= H. anomala ssp. petiolaris)
Habit: Climbing shoots/self-clinging, twisting a bit when old, 10-12 (15) m tall or creeping, 2-6 m wide with loosely overhanging twigs; very slow-growing the first three to five years, only fast when solid contact is made, 20-50 (80) cm a year.
Flowers: Flat white umbels, 20 cm long, attractive, sterile, white marginal flowers, June to July; only plentiful on old plants, fragrant.
Leaves: Early shoots, April; cordate to broadly ovoid, light green, gradually medium-green, yellow at the beginning of November.
Roots: Cordate, sensitive to soil compaction; the climbing shoots turn into roots in the first few days if enough moisture is present; normally turning into cork after two weeks and not changing again.
Demands: Sun to shade, avoids heat, tolerates warmth, likes cool, humid areas, frost hardy; somewhat tolerant of urban pollution (not on south-facing sides), wind resistant.
Soil: Fresh to damp; acidic to neutral, sensitive to chalk; humic and nutritious, well drained and loose substrates, very sensitive to heavy or compacted soil.
Note: Also overhanging or only a shrub without climbing aids; 1.5-2 m tall.
Hardiness: Zone 5b