Having a very poor germination rate this year. Only had 2 up so far and one of those promptly got ill. How long after stratification would you expect seedlings to germinate? Do you think some of them require a further cycle in the cold?
This year my first cycle out of cold stratification ceased any meaningful germinations ( aka 0) after ~ 15 days (criteria used was as in show me above ground).
At ambient temperatures (18-20C).
About 32 germinations of various very hardy roses.
The remaining seed trays back to ~4 C.
I suspect everybody’ is a variable experience out to 1 year for some spinos l am told - kid you not.
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My guess is that the seeds needed more stratification, although you didn’t say how long they were stratified or how long it has been since you moved them into the warmth. I would probably put them back into the refrigerator, which won’t hurt and should help if the duration wasn’t enough. Climate, weather, and rose selection could all have something to do with the different experiences that people seem to have with various routines, and it might take some trial and error to find out what works best for you. As a general rule, I leave my seeds in stratification for a year, and often longer for valuable or stubborn crosses. I wait for the seeds to germinate in the cold and then pot them up under lights as they sprout. This may be a bit more work, but it has always yielded decent results for me. Whenever I have pulled my bags of rose seeds out of the refrigerator and waited, I have never seen very much germination happening in the warmth–sometimes a little sprouting might occur at first, but that rapidly tapers off. Putting the seeds back into the refrigerator can get the process moving again, but it always seems to work better for me to just let them germinate in the cold.
Stefan
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James, for me, once removed from the fridge it is always the same bell curve. First germinations occur within 3-4 days, maximum per-day occurs at about two weeks, there are still a very few stragglers at about a month, and there is practically nothing after that. I’ve managed to squeeze a few more out with a quick 2 week re-refrigeration, but it’s hardly worth the effort.
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It depents, I have seeds from Newsflash which germinates really really fast and others take a long time. I got first Newsflash this week. Others germinated after a long time. Had a forbidden box from last season and they germinated last month. I was too late to notice sadly.
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Hello James_D!
If your question may also refer to Portland rose seeds with Portlands as mother plants, I generally recommend for this kind of seeds a warm stratification of 2-4 weeks at a temperature of about 21° Celsius, followed by a cold stratification period of 2 months at 4° Celsius. The achenes are then stored in semi-darkness at around 12° Celsius. When the contained embryos are viable, germination is starting fairly consistently about 1-2 weeks after that, regardless of the type of pollen donor. The seedlings all come up pretty much in bunches. In most cases, there is hardly anything worth mentioning afterwards. Should your cold stratification time have been shorter than 2 months, I would suggest a follow-up treatment. Otherwise, I would test a two-week rhythm: 2 weeks cold, 2 weeks warm alternately. Best of luck!
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I did 3 months in the fridge, then on a table in a coldish room. I then put two of the seed trays into a small glass porch which is in shade (cold/no heating) for 2 weeks. I have now had an initial 2 germinations since then. Would you say 3 months stratification is too much for Portland’s? I guess I will keep rotating them every 2 weeks back into that cold space, until spring fully kicks in. The fridge I use is tiny and sadly the seeds are now in trays too large to go into it. I will definitely be trying the baggie method of stratification from next year, as my current way is labour intensive and now I have had my first poor year, I think it’s time to trial another way.
You gotten background data tips experience and suggestions.
I give a bench mark or mile post of my experience, similar to other years. I would say my 35 germinations from the 1st cycle were from a sampling of 1000+/— seeds. I went super blender and screening methods for hip shucking.
Still waiting R kordesii (probably because didn’t spell name right in past) to germinate which is against the grain of experience of others.
Though there was a time l recall claiming super - germinator status when l had over 65-70% from R beggeriana. Never could figure out why others had issues with it ……… 
… all l can do is give the seeds the best chance using methods that have worked in past for me in actually getting a germination and tinker with it as your planning …
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First of all the baggie method is a good idea. I prefer it because it is much more flexible in handling.
Ultimately, it is difficult to judge whether the lack of germination activity is due to your stratification regime. I don’t believe that the three months of cold stratification are the problem. Rather, I fear that the gene mixing could be the cause. This is often a problem especially with Portlands. In particular, you can hardly draw conclusions from one year to the next. A successful crossing that worked well a year often cannot be repeated and vice versa. Of course, many influencing factors play a role in the whole thing. You mentioned that one of the two seedlings that germinated became ill. Normally the first flush still contains the strongest ones. That could be a small indicator for this assumption. However, I would also try as much as possible.
The aim now is to trigger a germination impulse by short termed extreme temperature contrasts.
If you have a large heating mat or underfloor heating, place the seed trays on it for a maximum of 1 hour. After that, I would move the trays to a cooler place. Repeat this process 2 times and then leave them in the cooler place. Light can also have a stimulating effect. I can’t guarantee that it will work for you too, but it’s worth a try. Good luck!
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… 2nding Roseus,
l also use baggies but in my case only for cycle #1 with seeds in pearlite … (-0C) and pearlite damped with plain water. Placed in a small bar fridge/ freezer.
I went below freezing because the wild species seeds wait out winter on/in frozen soil that in theory is just below freezing. Soil frost line anywhere 6” to less than 18” (building code requirement to be below it). Judging from striking frozen dirt/ ice in my garden at 4-6 inches in April l judge the engineers must be right, gads they’re bright 
.
Though judging from the southern British climate in winter (Dec) this is not useful to you what l do.
After cold strat done transferred seeds to small meat loaf with clear lids this year. Still only damp pearlite. Done because keeping treated seeds in baggies to await germination didn’t appeal.
This time containers stacked on top of one another and barely fit for cycle 2 in fridege…
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If only crossing rose seeds were as easy to germinate as micro seed hybrid poppies. My R. beggeriana try came close ……
First time l have noticed this “non guarantee” on a seed pack potted today.
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Got to chatting with Brad Jalbert, and it inspired me to plant my seeds out from the fridge at the beginning of February. THEN, we immediately had snow and two full weeks of below freezing temperatures!
I’m fairly certain most everything will survive, but waiting for day/night temps to hit the sweet-spot for germination is KILLING ME…
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