Ha, yes indeed Tim , many seeds need to be stratified. In horticulture as you know , stratification is a process of treating seeds to simulate natural conditions that the seeds must experience before germination can occur. Many seed species have an embryonic dormancy phase, and generally will not sprout until this dormancy is broken. Pines and most hard seeds need this .Sorry to be old mister negative Peter, but there is no way that freezing things will sterilise them. Biologicals such as bacteria, tissue samples, and seed libraries, are kept at -70 DegC to keep them viable. The master cell bank for the main product I worked on for thirty odd years was stored this way in the nineteen sixties and still gIves viable cell lines in 2022…for example.
Some seeds need to be frozen and thawed before they germinate as well. Can’t name any species off the top of my head, but I bet John can
Freezing can selectively reduce bioburden, killing such things as germinated annual plants by disrupting cellular material, as the water crystals grow large enough to burst structures if the freezing is done slowly. However, the only way to sterilise anything (achieve a six log reduction in viable biological material) is by filtration, by heat, by treating with chemicals, by exposure to ultra Violet light, or by exposure to radiation. This was a standard interview question for biopharmaceutical production candidates throughout my career
Basically it's reproducing a winer period to encourage the seed to sprout .
The risk of not treating soil is having a sudden growth of seeds on the diorama, something which I don't want
mostly it won't happen .
