I’ve germinated a fair number of rose seeds, but I’m by no means an expert. So I have some questions that I’ve always wondered about for the experts out there:
- Are floaters always non-viable?
- Is there a definitive correlation between seed size and viability, and/or eventual seedling survivability?
- Can seeds die if left on the plant over the winter in a cold climate (Zone 4 here)?
Thanks for your help! I’m going to ask some follow-up questions for each original question:
- In non-Rugosa seeds, is there a correlation between floating and being non-viable?
- I’m going to rephrase my question to read “Is there a definitive correlation between relative seed size within a given hip and viability, and/or eventual seedling survivability?” I’m noticing huge seeds in some of the hips I’ve been processing, but then also many tiny seeds. I’m wondering if anyone has drawn a correlation so I don’t waste my time cleaning and treating all those tiny seeds if they’re likely to be non-viable.
- I haven’t done any dissection of seeds to look at the embryos before. What should I look for as far as how a viable embryo would look compared to a non-viable one?
Thanks again for your help! I appreciate it!
Don Holeman would be the best person to answer these questions.
When I attack a seed with the clippers, I figure if it looks white and somewhat plump inside it’s probably still good. Usually I screw up and squish out some white stuff. If the embryo is dead, missing, or non-viable it would likely be brown inside or absent. Don’t be afraid to just try it with seeds that are fully expendable - just start clipping away with a fingernail clipper until you get to the middle. There is a brown skin over the embryo, but if you squish it it should be white inside.
I’m hoping Don Holeman will see this and give some advice. I can’t find him on the list of members. Not sure what his username is.
Hi Tony. I’m a beginner here. Don Holeman’s guide to embryo extraction, plus videos by others of the process at: Embryo Extraction from Spinosissima(?) Scotch Rose Seed - Rose Hybridizers Association Forum
Are floaters always non-viable?
Peter Harris once sent me a batch of floaters to test this question, I extracted embryos from a couple hundred of them. The first 199 had no embryos. The very last one had a fine embryo.
Is there a definitive correlation between seed size and viability, and/or eventual seedling survivability?
This is basically the same situation as floaters. In a batch from a single cross having a bimodal distribution of large seeds and very tiny seeds the tiny ones probably do not have embryos but you just cannot be certain. I decide which to keep and which to toss depending on how important the cross is to me.
Can seeds die if left on the plant over the winter in a cold climate (Zone 4 here)?
It depends on how well dessicated they are before they freeze. I just recovered three hips off of Bill Reid that I had missed in the fall and queued them up for extraction, and I do the same pretty much every season. Keep in mind that the international seed repository is located in the arctic. In fact, I once extracted embryos from omeiensis seeds obtained from the USDA that had been in the deep freeze for 25 years. Two embryos out of (iirc) 19 seeds germinated and I still have both plants (last I checked).
Yes, thanks very much Don! And thanks to jbergeson and Roselyn too!