Artificial (temperature controlled) pretreatment/germination with medium for deeply or shallowly dormant tree seeds.

The advantage of this method in comparison to the “easy” method is that the pretreatment temperatures are less susceptible to the vagaries of the weather.

1. Determine prescribed cold, or warm plus cold pretreatment durations for individual species and use “Approximate date to initiate artificial pretreatment” as guide to likely start date.
2. Prepare a moisture retaining medium by mixing one volume of an organic material (such as peat, decomposed leaf litter, or peat alternative) with one volume of a coarse particle material (such as sand, grit, perlite or vermiculite).
3. Place moisture retaining medium into a seed tray. Sow seeds. Place seed tray in loosely tied poly bag (to retard drying, but allow gaseous exchange).
   
4. Transfer seed tray to appropriate conditions for prescribed durations of cold, or warm plus cold. Use a ‘cool’ room (10 to 15 deg C) for the warm phase – avoid an airing cupboard (too warm) and window ledge (too variable). Use the main compartment of a refrigerator for the cold phase – avoid the icebox or a deep freeze (too cold).
5. Inspect seeds regularly (preferably weekly to fortnightly) for the following:
   • Re–moisten the stratification mix if necessary.
   • Remove decaying seeds to prevent the spread of fungal infections.
6. Either:
   • Remove and sow germinating seeds at each inspection.
   • Apply the prescribed pretreatment duration and on completion transfer the seed tray to warmer conditions; or
   • Wait until approximately 10% of seeds have begun to split, chit or germinate and transfer the seed tray to warmer conditions.