Sorbus aucuparia, commonly known as rowan or mountain ash, is a hardy deciduous tree native to Europe and western Asia belonging to the Rosaceae family. The species is valued for its ornamental white spring flowers and bright red berries that feed wildlife. Seeds exhibit deep physiological dormancy requiring extended cold stratification to break dormancy and achieve successful germination.
Before sowing
Perform warm stratification for 2-4 weeks at 15-25°C, followed by cold stratification at 1-5°C for 14-16 weeks. Alternatively, use direct cold stratification for 75-105 days at 4°C.
Sowing
What to expect
Tips
Seeds have deep dormancy requiring patience. Expect slow and erratic germination over 2-4 months or even 2-3 years. Monitor pre-treating seeds regularly and sow when approximately 10% have chitted. Do not cover seeds with compost; light is beneficial to germination. Avoid high seedbed temperatures (above 20°C) which inhibit germination. Use fluctuating temperature conditions during winter stratification for improved results. Ungerminated seeds can be retreated to stimulate additional germination cycles. Seedlings grow slowly initially but develop strong root systems; keep young plants in cool conditions for the first 1-2 years.
Sources: Sheffield's Seed Company, RP Seeds, Forest Research UK, Plant World Seeds, Treeseedonline, PFAF Plant Database
