Storage moisture content and temperature
9-12% @ < -5°Ca
8 (6-12) weeks cold (c. 4°C)
Efficacy of pretreatment / remarks
Generally effective, a significant proportion of live seeds should germinate
Approximate date to initiate artificial pre-treatment (for 1 March sowing) 4 January
Intermediate - seeds that can only be partially dried or need very slow, careful drying. They deteriorate more quickly than 'orthodox' seeds but more slowly then 'recalcitrant' seeds.
Orthodox - seeds that can be dried without harm, and once dried can be frozen, stored for years with little deterioration and relatively easily revived.
Recalcitrant - seeds that cannot be dried or frozen and are therefore short-lived.
(?) - indicates storage characteristics are not yet fully understood.
a Maximum advisable storage c. 3years @ c. 10% moisture content & -10°C
Figures in brackets indicate that different seedlots often require different pretreatment durations. There are three potential courses of action:
- Adhere to the pretreatment duration in bold, with the knowledge that the maximum potential germination of the seedlot may be sacrificed for the sake of simplicity.
- Inspect the pretreating seed regularly. Sow when c. 10% of seed is chitted, with the hope that this is indicative that the remaining seeds are now close to germination.
- Inspect the pretreating seed regularly. At suitable intervals, remove chitted seeds (by hand, flotation, and/or sieving). Sow chitted seeds and return balance to pretreatment until no more seeds germinate.
Raising Trees and Shrubs from Seed (PDF-648K)
Forestry Commission Practice Guide 18.