I was getting some of my seeds ready for cold treament last night when I noticed that some of the seeds had germinated already. These seeds are from a batch of seeds that have been in warm treatment for 60 days. I was really surprised by this as all of the seeds in this batch are from cold hardy plants. I would have thought they would need a good cold treatment before germinating. All of the seeds are from the same seed parent, but from two different pollen parents. The seed parent is a (John Davis OP)OP plant and the pollen parents are Bonica and Graham Thomas.
Because I wasn’t expecting there to be any germination I hadn’t been keeping close tabs on the seeds. So the roots on several of them had grown fairly long and the tips had turned brown. I had read on the forum of someone using rooting compound on their seedlings when this happened to them, but I can’t find that post now. If they read this I would love to know how well that worked for them.
Early on I always sowed rose seed without stratification and had a surprising degree of success. Certain seed parents seem better at providing germination this way than others. It’s the lazy man’s answer to creating seedlings.
I rarely sow without stratification anymore, mainly as I’ve discovered the germination is more reliable and less erratic time with cold treatment. It’s also true that other cultivars require germination cold for germination.
I started working with yellow more and was advised that the genotype of yellow hybrids is more dependent on cold stratification.
Someday I may go back to sowing seed straight away just because I don’t have to create a great number of seedlings or invest as much time and effort.
I think it really depends on how obsessive one chooses to be about creating new roses.
Dr. Neville Arnold spoke about warm germination at the ARS National in Denver. He said that he gets close to 90% germination with his cold hardy hybrids.
Hopefully, Dr. Arnold will write an article for RHA soon.
Paul, as long as the upper part of the seedling hasn’t turned brown, you may be OK. Just break off the brown part (or slice it off diagonally with a razor) and plant the seedling. It wouldn’t hurt to slip a loose baggie over the pot for a few days, maybe a couple of weeks even, since the seedling has no roots. If the seed leaves are totally exhausted, your plant should survive and grow.
One of the questions I had last night was, since some of the seeds had germinated already with just warm treatment, do I continue the warm treatment to see if more germinate, or do I proceede to the cold treatment? I opted for the cold treatment. Based on your experiance, it sounds like I made the correct choice. But I am going to keep a close eye on them as they may start germinating sooner than I am expecting.
I have read that one is more likely to be able to germinate seeds without cold stratification in hot climates than it is in colder climates. I believe it has to do with how warm it is when the seeds ripen. So one will have more success doing that in southern California than they would in the more temporate midwest. I believe what I read was comparing the same cultivar in one region versus the other.
Another reason that hot climates may have better success without cold stratification is because the cultivars that grow well there are plants that have species in their genetic makeup that evolved for those conditions. Whereas plants that grow well in the colder midwest have species in there background that evolved for those conditions, hence the requirement for a cold treatment. That is why I was surprised I had seeds germinating already with cold treatment.
Anyway I don’t know if sowing seeds directly is a viable option in Minnesota or not. I don’t know if anyone has tried it. I should try that with some OP seeds and see what kind of results I get.
The upper part of the seedlings looks fine. I will take your advice and trim the end off of the root and cover them with something. Do you use rooting compound on them after trimming them?
Meg,
Are you sure that Neville claimed a 90% germination rate? Could you have misunderstood him? That is a very high rate for cold hardy roses. He and I were corresponding this spring and this is what he wrote to me in an email:
“Germination for winter-hardy roses in my case is between 10 and 15 percent and occasionally may be as high as 50 percent. Considerable variation may occur between the years.”
If he claimed 90% in Denver then I don’t have an explanation for the discrepancy with what he emailed me.
I would love to see an article from Neville as he is doing great work and him sharing his experience with us would benefit us all.
I re-read you post and I realize I didn’t fully grasp what you were saying the first time. Is Neville claiming that he gets 90% germination with just warm treatment? If he did, that would be quite a revalation. Did he go into any details like how long he treated them for or at what tempature? A lot of us would would be very interested to know how he did it.
It may have to do somewhat with how long the seeds remained in their hips. One school of thought has it that the seeds absorb germination inhibitors produced by the hip walls. I’ve always thought that the period of pre-stratification “imbibing” that some people do actually acts to leach these inhibitors from the seed more than it does to allow them to imbibe water.
I was pretty sure of the germination rate since I was shocked at the numbers he quoted in his talk.
I asked him specifically about the number and he repeated it with a twinkle in his eye because he knew that it was extraordinarily high compared to the cold stratification that most hybridizers are using.
Take a look at his web-site for some interesting information and some lovely pictures of the roses he is using in his breeding program.
I am of the same understanding and rinse my seeds periodically to help leach these inhibitors out. If that is what is actually going on, are these inhibitors leached out faster/better at warm temps than at cool temps? Is that why a higher germination rate can be achived with just a warm stratifaction than with a warm then cold stratitifaction? I’m planning on testing this with some OP seeds.
I first heard of the concept in an RHA newsletter way back when, in fact. There’s also part of a chapter (3.6) in Buckley’s “Germination of Rose Achenes” titled “Warm, or Imbibation Period”.
are these inhibitors leached out faster/better at warm temps than at cool temps?
Yes, but I doubt the difference is significant on the scale of weeks. I change the paper towels if I see them picking up color around the seeds for that reason, refrigerated or not.
The leaching is only one part of the germination mechanism, as I understand it. There’s also the changing ratio of gibberellic acid to abscissic acid, softening of the sutures in the pericarp, and the undoubted influence of chants, spells and incantations.
Is that why a higher germination rate can be achived with just a warm stratifaction than with a warm then cold stratitifaction?
This premise seems to be true for some roses but not others. Given the ancestries of modern roses (subtropical China to subarctic Siberia) I doubt you could predict which would be more amenable to either treatment.
I’ve never had to use rooting compound. Those stems have lots of undifferentiated cells, and form roots very quickly. I’d suggest that you take off the bottom half, to make sure that you get rid of all the stuff that’s turning brown and have good firm root stems with good color.
I would be shocked too if I heard that number. It is interesting that Neville’s website and what he was telling me this spring is not the same as what he reported in Denver. This may be something he has been working on but wasn’t ready to report on it until then. It’ll be interesting to see if he writes a paper on his findings.
Don,
Given the ancestries of modern roses (subtropical China to subarctic Siberia) I doubt you could predict which would be more amenable to either treatment.
I agree, the only way to truely know for sure would be to test each variety you intend to use before doing anything on a large scale. I’ve already collected hips from 5 or 6 varieties to do a test to see if I can re-create Neville’s findings.
I may have been the person you were referring to who uses rooting hormone on seedlings. Sometimes I have left seedlings in the bag until they are quite elongated. When that happens, I will cut the root and lower stem off, leaving about 1 inch of stem under the seed leaves. I
Thanks for the update. Between Peter’s and your information I feel more confident that I can save the little guys. And that is good as I don’t have that many seeds of those two crosses.
I have planted seedlings in the past that have had root damage, but I didn’t trim off the ends and I didn’t cover them up either. I don’t think they did very well but I’m not really sure as I didn’t keep track of them.
Some of the germination rates I got without chilling were pretty good, but I don’t think I’ve ever had a 90% germination rate chilling or sowing fresh.
There might be seed parents that consistently give 90% germination rates but I don’t know of any.
Every seed would have to be perfect. In modern hybrids that just doesn’t happen.
Btw, I have used Joan’s method for rooting seedlings without rooting hormone and it worked just fine. I never use hormone.
It’s one more thing to deal with and I want to breed roses that root easily. If they don’t root I move on. I consider it part of the culling process.
It would seem that there is some kind of misunderstanding concerning percent germination. I have never had 90 percent germination, however, I do know of individuals who claim this to be true. I was at a presentation on rose seed germination at McGill University, Montreal, Quebec and the speaker claimed 100% germination. The latter would seem to be a bit high as I have performed embryo rescue on a number of different hardy roses and found a high number of dessicated embryos. It was never my intention to mislead anyone on the percent germination I have with my crosses. However, my sincerest apologies if there was a misunderstanding.
The information I gave you in my communication is accurate. “Germination for winter-hardy roses in my case is between 10 and 15 percent and occasionally may be as high as 50 percent. Considerable variation may occur between the years.”
Further, the seeds from my crosses are warm stratified for 60 days at room temperature followed by 90 days of cold stratification at refrigerator temperature. During both of these periods the seeds are in a slightly moistened coarse sand. A few seeds will germinate after 60 days warm stratification which are planted in 2 inch square pots filled with a rich soil mixture. But most of the seeds that germinate will do so after 90 days cold. On one occasion I forgot the seeds in warm stratification for 90 days and a good number did germinate and developed rather long root.
The 60 + 90 day regime suits me fine as I do not have to heat a greenhouse during the winter in Green Valley. Temperatures in the winter can reach -40C (-40F) with the wind chill. I am in Canadian hardiness zone 5 USDA zone 4.
With respect to an article, I doubt that I could add anything significant to rose breeders who are so well versed in the art of breeding. The only added precaution that I take is applying a circular piece of voile (fine curtain material) around the hip after emasculation and again after pollination. The voile is fastened with a small piece of twist tie. Further each cross is identified with its own label.
I believe that the piece of voile will also protect my crosses from the pollen of genetically modified roses. I am sure that many of you know such roses will be introduced to the market in the near future. This little bit of protection will save you much potential heartache.
Again, I wish to sincerely apologize if I accidentally misled anyone on the rate of germination.
