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10-15% @ < 0°C
4 (4-8) weeks warm (c. 15°C) plus
8 (8-12) weeks cold (c. 4°C)
Generally effective although pretreatment durations, and numbers of repeat cycles may vary significantly between seedlotsApproximate date to initiate artificial pre-treatment (for 1 March sowing) 6 December
Orthodox – seeds that can be dried without harm, and once dried can be frozen, stored for years with little deterioration and relatively easily revived.
Figures in brackets indicate that different seedlots often require different pretreatment durations. There are three potential courses of action:
Raising Trees and Shrubs from Seed (PDF-648K)
Forestry Commission Practice Guide 18.
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