I’m a complete novice, but I want to learn to breed roses. I started by just trying to germinate some seeds from hips I found on my Shadow Dancer, but even though I treated them with a hydrogen peroxide solution, when I left them in a ziplock bag with a damp paper towel, they ended up covered in some kind of black mold or mildew. How can I prevent this? I have the other half of the batch of seeds stratifying in the fridge (I didn’t stratify the half that already molded). I’d like to take them out of the fridge and try to get them to germinate, but there’s no point until I know how to keep them from molding. I am planning to buy some perlite to mix with potting soil, both for germination and for growing cuttings, if that helps.
How can I stop the mold?
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Not all mold is bad, so it may not be the end of the road for those achenes (the mold is likely on the surface of the outer shell and not the actual seed, per se; also, non-pathogenic molds can actually play a role in helping to break down barriers to germination). People here have different preferences when it comes to stratification media, and you’ll find a lot of discussions if you search for them. Personally, I avoid paper towels, sterile potting media, and using only peat moss. I like to blend milled peat and commercial compost/manure (say, 60/40 to 70/30, depending on the consistency and aging of the latter ingredient) to use for both stratification and as a potting medium. I feel that the microorganisms that are already present in that mix help to keep pathogenic organisms from getting the upper hand. I rarely seem to have viable seeds destroyed by mold in stratification, and my results are more consistent than with other media I’ve tried. Also, because I stratify in plastic bags, having a medium that is very dark in color (without Perlite) makes it much easier to see the germinating seeds so that they can be removed and potted. If you are stratifying in pots or trays, that wouldn’t be an issue, of course.
For cuttings, you will probably want a different mix than the above. Usually peat moss and Perlite or coarse vermiculite make a good combination, but a sterile potting medium without added fertilizer may also work. Of course, everyone’s preferred methods vary. I usually pre-callus my cuttings in water before sticking them, so a sterile medium isn’t quite as critical for success.
Stefan
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I think it’s worth mentioning that the bags should stay open, not sealed. I wish you success!
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I always seal my bags (with air)–otherwise, everything would dry out.
Stefan
I’m always learning, thank you!
Too long I cobbled together my own methods, before joining this forum.