Ailanthus altissima, commonly known as tree of heaven, is a rapidly growing deciduous tree native to northeastern and central China and Taiwan. Despite its ability to germinate without stratification, cold stratification significantly improves germination rates to 75-96%. The species exhibits physiological dormancy at cool temperatures but performs better at warmer, fluctuating temperature regimes.
Before sowing
Cold stratification improves germination rates significantly but is not strictly required. Seeds can germinate without stratification but at lower rates.
Sowing
What to expect
Tips
For best results, soak seeds in room-temperature water for 24 hours, then cold stratify at 4°C for 60 days. Seeds need light for germination and should be covered lightly with soil (1/4 inch or 0.5 cm). Maintain soil moisture without waterlogging. Autumn outdoor sowing in mulched beds is an effective natural alternative to artificial stratification. Germination typically occurs within 7-28 days at 20-25°C. This species is highly invasive; consider ecological impacts before cultivation.
Sources: Pepe et al. (2020), Kheloufi et al. (2020), USDA Forest Service, Sheffield's Seed Company, multiple peer-reviewed studies on Ailanthus altissima germination biology
