I know there are as many different ways to clean and treat seeds as there are hybridizers. If the seeds are going to be soaked for 24 hours as David’s research indicates, would the seeds germinate better if the water was changed a few times and the seeds were rinsed when the water is changed? I know there may not be a consensus on this, but your input and opinions are appreciated.
Robert, that would be a very good experiment to try. I once stored rose seeds in a large jar filled with water and had an airstone hooked to a pump in the water to aerate the water. I changed the water a couple of times. I did get some germination, but didn’t see any improvement and it was quite the hassle to have this all hooked up with the jar in the refrigerator!
I soaked the seed for 24 hours after the drying / constantly moist treatments just to try to ensure more uniformity among the seeds for moisture content before going into cold stratification. Cold stratification relies on cold plus moisture and if an acceptable moisture level isn’t there the stratification treatment isn’t perceived. I don’t know if my seeds were fully imbibed by then or not. There is a reference working with op seed of ‘Crimson Glory’ that full imbibition may take more than 24 hours. Hopefully they were imbibed enough for the threshold to allow for a more uniform perception of stratification.
For my general seeds when I have a few families I might still soak them overnight, but in general I don’t anymore. I put the cleaned seeds (right away without drying them down) in moist peat in baggies. I then keep them at room temperature for a few weeks or so and then put them in the fridge. This warm stratification treatment as described by Julie Overum’s masters thesis and work done with the Dogroses seems to allow some germplasm to germinate better later after cold stratification and in other germplasm there is not a significant difference relative to putting the seeds in the fridge right away. I see some fungus on the seeds eventually while at room temperature, but it doesn’t hurt them it seems and may allow for better penetration of water. Perhaps it’s one of the fungi that produces gibberellins and would be beneficial??? I have been thinking about culturing this fungus I routinely see on some petri plates and asking a plant pathologist to help me key it (or more than one?) out to learn what it is. Using warm stratification before cold also helps me in delaying final germination to later in spring which is good because I have limited plant stand space.
Some while back, Joan Monteith or Henry Kuska (if I remember correctly) mentioned hanging a net or mesh bag of seeds in a toilet tank for a long time. I don’t recall that it led to a tremendous increase in germination. That might have been posted on the GWeb Rose Propagation and Exchange forum–or maybe it was in the RHA Newsletter. I don’t recall at the moment.
Three weeks ago, at a general plant talk, the speaker mentioned the role that humic acid plays in softening seed coats.
From years ago, I’m not sure that humic acid isn’t a catch all phrase for the breakdown products of organic decay.
But if humic acids are good, then dirty would be better?
Subject for library research in winter?
Well this year I am trying something different so maybe I can help answer next year. This year I harvested a minor bit early–right before the seeds turn brown. I let the hips sit in the fridge for 2 weeks. I planted each cross into its own black plastic pot (I’ve done this before after the usual method–I just mass cull anything inferior until one is left, it is very economical and stresses the seedlings to see who is a wuss and who is worth staying!). I want to see if the sway of daily temps/light combined with the cold winter nights is enough. I planted them shallow, too. I don’t see why not. Fridges are not really all that cold anyhow. They dont have wind chill factors even. Anyhow, I hope this works because it cuts down the work load dramatically. Also, I cleaned the seeds but they would technically be “dirty” because the media I used is only half sterile. I did this last year with one tray and had 0% wilt. I had 5 wilts inside in a sterile mix (which is low, too).
I hope this works because I really do think we make things too complicated. The only excluding factor that I can think of would be if it was a picky species or perhaps a rare cross.
I don’t jump through any hoops to prepare my seeds. I find that germination rates usually provide me between 4000 and 7000 seedlings per year, which is more than enough for me.
I collect hips when I feel like it, which is usually now. Often, I am picking up fallen hips off the greenhouse floor. They are sorted by cross and stuffed into large Zip-loc bags. The bags are stored indoors in a room that hovers around 65F, for about a month, then moved to the fridge. Around mid-December I start removing the seeds, again, when I feel like working on it. I use a knife that has had the tip broken off and the broken end ground down to a very round end, just right for popping seeds out of the hip. At this point, many hips are rotting and often cultivating at least one species of mold. My early trials suggest that moldy seeds germinated somewhat better than ones kept sterile/clean. (I believe molds help break down the coat of the achene) Shucked seeds go back into bags with a wet paper towel, and NO FUNGICIDES. I sow them in early March in trays, in labeled rows. The greenhouse they are in is unheated, and so they experience all the temperature fluctuations of the open air. I do cover the seed trays if temps go below 30F though. The seeds germinate. No special soaks or labor intensive tricks involved. I think that you can go too far in working to get maximum germination.
Remember that if you work out a lot of complicated techniques to improve germination, you may be slowly selecting for roses whose seeds become increasingly difficult to germinate. That is definitely something to be avoided, I believe. Just my 2 cents.
Great advice Paul! Simplifying is the key. I think that you are right about some molds helping with germination.
I so agree Paul. However, I would never discourage one to explore to possibilities of new and/or better methods (Im not implying you are btw-- just an afterthough of our combined statements.
Thanks to everyone for their replies.
Jim I will probably try to set up some simple experiment using very well cleaned seeds compared to some seeds not cleaned well.
David, thanks for all your good posts and interesting information.
Peter, I also remembered the tea bag in the toilet after you mentioned it, but I don’t remember who posted the information or the results.
Ann, I think you are right about humic acid. Acid scarification or microbial digestion can weaken the seam holding the two halves of the seed together. Humic acid is probably one of the keys to natural germination.
Jadae, keep us posted of your ongoing experiments.
Paul, thanks for sharing your seed germinating procedure and all your good information with us.
I’m sorry if I gave the impression that I discourage exploration of new techniques for seed processing! That was not my intent. I simply wanted to express my personal experiences and the feeling that one can get too involved in seed preparation than necessary to get good results. I personally find I am most comfortable when the process is simple and easy to execute.