Most seed is dormant and benefits from being pre-treated to ensure sufficient and even germination. Different species have different dormancy breakage requirements. Recommendations to break the different level of dormancy are given below, but these should be used for guidance only since there is variation in depth of dormancy between different seed-lots of the same species. Small amounts of stratified seed,(dormancy broken)of certain species is available in the spring. Please phone to enquire.
Non Dormant e.g. Oak, Horse Chestnut, Sweet Chestnut
These seeds are either not dormant at harvest or have a dormancy which disappears naturally during storage or in the soil when sown. They do not require any stratification.
Pre-Chilled e.g. Alder, Birch, many Spruces
These seeds are not actually dormant but will germinate more quickly and evenly if given a moist chilling (or pre-chill) at 0 to 2degC for up to 10 weeks. Soak the seed in running water for up to 48hrs, drain thoroughly, place in a polythene bag, tie lightly and mix regularly during storage. Sowing can be anytime after about 3weeks of this treatment.
Semi-Dormant e.g. many Firs and Cedars
These seeds will not germinate at all unless given a moist chilling treatment. Use the same method as 'Pre-Chill'
Mildly Dormant e.g. Rowan, Sycamore
These seeds will not germinate unless given a lengthy period of chilling. After soaking the dry seed in running water for up to 48hrs, drain and mix with sieved peat and sharp sand in equal volumes. Place the seed in a polythene bag, tie lightly and store at 0 to 2 degC. The number of weeks chilling depends on the species e.g. Rowan=16wks, Sycamore=12wks. Gently shake the bags to aerate.
Deeply Dormant e.g. Cherry, Holly
These seeds require a lengthy period under warm, then cold conditions. Natural fluctuations in temperature are the most effective, but the conditions can be given artificially using a warm room and a refrigerator. Using equal volumes of sieved peat and sharp sand, mix fresh seed with an equal volume of the peat/sand medium. Dry seed will need to be soaked for up to 48hrs then drained before mixing with the medium. Dry seed often has a more even germination if stored for 2 weeks at room temperature before putting in the fridge. The number of weeks chilling depends on species e.g. Cherry =29wks, Holly = 64wks. Shake bags gently to aerate, once or twice a week.
Leguminous e.g. Lupin, Broom
These are typical legume seeds which have a condition known as 'Hard Seededness ' where a fine layer of wax prevents seed from absorbing moisture. The wax must be punctured by rubbing on sandpaper or lightly scraping with a blade. The treatment can be monitored by soaking the seed in water and noting the percentage of seed swelling. Un-swollen seed, i.e. that which hasn't imbibed any water will need to be scarified again.