Examples: Most broadleaves e.g. ash, beech, cherry

A few conifers e.g. juniper and yew.

Overview

All these seeds (whether freshly collected or stored) are incapable of germinating under any conditions until pretreated. Pretreatment consists of incubating seeds for a relatively long period of time (8 to 64 weeks) under moist conditions. All species can be pretreated either naturally or artificially. All can be pretreated in a moisture retaining medium, a few can be pretreated without. Some need cold only (c. 4 °C) others warm (c. 15 °C) followed by cold (c. 4 °C) – for recommended pretreatment durations for individual species – seed pretreatment tables.

Methods

There are several potential methods which can be used to pretreat deeply dormant seeds. Three are described below:

• Easy: Natural (outdoor) pretreatment/germination with medium for deeply or shallowly dormant tree seeds
• Moderately easy: Artificial (temperature controlled) pretreatment/germination with medium for deeply or shallowly dormant tree seeds
• Skilled: Artificial (temperature controlled) pretreatment without medium for deeply or shallowly dormant tree seeds.