Koelreuteria paniculata, commonly known as the Golden Rain Tree, is a small to medium-sized deciduous tree native to China, Korea, and Manchuria, prized for its stunning golden-yellow flowers and ornamental seed pods. Germination is challenging due to pronounced seed dormancy involving both a hard, impermeable seed coat and internal dormancy; proper scarification and cold stratification are essential for successful propagation.
Before sowing
Seeds exhibit both exogenous and endogenous dormancy. Hot water scarification followed by cold stratification is essential. If boiling water treatment fails to allow seed imbibition, sulfuric acid treatment may be required as an alternative.
Sowing
What to expect
Tips
Fall sowing in mulched beds is preferred to artificial stratification and may provide more natural germination. Be patient: germination can be sporadic and occur over a 2-3 year period. Do not discard seed immediately as dormant seeds will germinate when conditions match their natural requirements. Once scarified and cold-stratified, sow seeds in moist medium (avoid waterlogging), tamp soil gently, and maintain medium moisture. After germination, transplant seedlings to individual pots and provide greenhouse protection during their first winter before hardening off for outdoor planting.
Sources: USDA Forest Service, UF/IFAS, TreeHelp, Sheffield's Seed Company, Plant World Seeds, Trees and Shrubs Online, ResearchGate (Rehman & Park 2000), PFAF Database, Australian Seed, Buy Tree Seeds
