Seed germination is a combination of biochemical and physiological phenomena influenced by environmental factors and the intrinsic conditions of the seed. The seeds of many tree species are difficult to germinate due to the hard and impermeable external integument and “embryo dormancy” phenomena. Autumn sowing or stratification allow for the post-maturing of dormant embryos and the modification of the seminal integuments. Stratification is more laborious and expensive but has the benefit of an easier controlled and more definite positive result. An early, cold autumn cannot ensure that the seeds sown would receive the necessary hot days for the first post-maturing phase and an early Spring could anticipate germination with the risk of compromising the sowing due to a delayed freeze. Seeds are prepared for stratification by immersing them in water for a minimum of 24 hours (up to 5-6 days for the hardest of seeds); they are then mixed with a substrate and placed in boxes or net bags.
It is important to maintain a constant but not excessive humidity and to check the progress of the germination process every 15-20 days
Towards February-March you should intensify the monitoring of the seeds and as soon as the seed begins to hatch it should be sown promptly. On the website we provide some general indications about the duration of the stratification and sowing periods. The duration often varies due to the seed vintage and the seasonal trend.
Substrate C: 50% peat – 50% sand and moistened
Substrate S: 100% wet sand
Substrate N: No substrate (seeds can be stratified and moistened in plastic bags)
We make notes on the basis of acquired experience in sowing each type of broadleaf which we recommend to our readers.