In the forum topic First embryo germination success is a link added by Don, on 9 Nov 24 (see page 9 of the document), which indictes freezing is possible but not for all rose types. Just in the fridge is the more common approach - kept moist in a medium and/or plastic bag. I am a beginner breeder and have learned a lot following forum topic searches, as VanIsle suggets above. Good luck.
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