Sometimes I get frustrated with myself.
I have the perfect situation to hybridize roses. A nursery and greenhouse business with cultivated land for growing things. A mist bed for propagation. And if I ever decide to sell my roses, patented or not, I have the marketing structure in place to mutually benefit sales of the rose and my business’s reputation. Hybridizing roses is the one thing in my life that I have taken seriously and worked hard at, the one true passion in my life.
I’ve always struggled with what I perceive to be low germination percentages, and have this tendency to jump right in to a new stratification method without testing it. Like the year I killed a lot of seeds by soaking them in pure bleach.
This year I think I’m drowning them. I decided to use activated carbon as my stratification medium. I moistened it and put some in the baggie as I removed the seeds from the hips so that they didn’t dry out. Now when I see that other people are getting germination I break out my baggies and see none. The seeds have all turned black and are difficult to find in the carbon. A lot of the bags seem really wet, too wet. I broke out a fingernail clipper to spot check on the embryos of some expendable seeds. In several cases the achene split at the suture just rubbing it between my fingers, so maybe that’s good or bad that the achenes are softening. However, in several cases the embryo was white but watery…definitely not alive, but not apparently the victim of obvious fungal infection. In other cases the embryo was just black mush. In a few cases the embryo sac (whattya call it, the thin brown wrapping around the achene?) was firm so I couldn’t get myself to squish it and tucked it into a tray of seeds I have in soil under lights.
I hope I’m overreacting. It seems like rose seeds are tough and despite my best efforts I never succeed in completely failing. However, I’m frustrated with myself for this weak link in all of the effort I’ve put into the hybridizing process. I need to come up with a protocol from hip collection to transplant that works for me.
I think as soon as I have time I will sow all of me seeds into seedling flats and return them to cold stratification. (Any method that involves picking seedlings out of baggies wouldn’t work for me because I have soooo many crosses to keep track of and no time for that in the spring.) I will cover them with Perlite or vermiculite, which seemed to work last year.
Next year I think I’ll use moistened Perlite or Vermiculite in the bags and try not to get it too wet. Perhaps moisten it with the 3% hydrogen peroxide solution that Don describes in his embryo rescue protocols. Soak the seeds for a few minutes in a stronger solution before putting them into the perlite.
Anyways, I’m just blabbing. I don’t really have a particular question, but appreciate any discussion you may have.
I’ve never used charcoal. Was this pure stuff purchased as such, or left over from a fireplace? Charcoal from trees burned, is full of potash as the hydroxide, like oven cleaner. Pure activated charcoal is supposed to be neutral. Crushed charcoal briquets have a lot of binding agents in them. I never tested their pH.
One part vermiculite to 2 parts water by weight seems to be the ideal proportion to go a whole year in the cold in baggies and keep on chugging. I can get 80% on R canina when I use early harvest seed and calcium nitrate. Takes a year or more but they keep on sprouting in the fridge. So if you want to just stratify a fixed time then plant in trays that proportion is good. Peat is good too but very hard to know the starting moisture content of a bale, and about impossible to get moistened if it is totally dried. Soak, then squeeze “dry” by hand is about right.
If it was easy it would not be worth the effort.
Your experience is exactly why I set about learning how to excise the embryos from my seeds and germinate them in-vitro. From my experience with this I know that most seeds have no embryos and most embryos that do exist are already infected with something and/or are already dead or dying whether from infection or other intrinsic factors.
I think that processing achenes with peroxide is probable not worth the effort. The use of systemic fungicides on the mother plant probably is worth the effort.
Years ago Rob Rippetoe (iirc) told me that black seeds are dead seeds and that proved to be the case as I was developing the extraction techniques.
On average about five to eight percent of seeds have viable embryos, though some crosses are much better than most others. Float/sink is a good determinant of the presence of an embryo.
I also realized that stratification mostly killed seeds, especially when using soil to stratify but really any medium that supports microbes acts detrimentally. If you search here maybe eightish years ago Jim Sproul outlined the method he settled on which was basically to soak the seeds, towel them dry and bag them in polyethlene baggies and pop them in the fridge. If you can’t find the post then write to Jim and ask him to weigh in. I support that method with the caveat that very cold storage works best because it maximizes oxygen solubility.
An apparatus mounted in a refrigerator that very slowly flushed the seeds with clean ice cold water would be ideal, say a drop of cold water every hour on a handful of seeds.
If you choose to extract embryos and germinate them in-vitro then the sooner you do it after harvest the better. Storage, whether fully dry or fully imbibed, cold or not, takes a toll.
Hang in there. Spring is right around the corner, the solstice is already a month behind us.
Thanks, Larry and Don. I appreciate hearing from you.
Larry, it is high grade carbon.
Don, your systemic fungicide hypothesis should be tested. If one could near magically increase viability from 5-8% to 50-80%, well, that would be knowledge most worthwhile. The first step would be, perhaps, to guess which type or class of fungi might be responsible and then try to find an appropriate chemical to try. I don’t think there are that many systemic fungicides (?) so maybe just pick a few and try them. If you have the motivation to do some of the preliminary research I would be willing to purchase the fungicide and set up some sort of trial here. (Within reason…I just paid $700 for a pint of something for impatiens downy mildew.)
One conflict of ideas is the need for a warm stratification period contrasted with Don’s observation or theory that warm temps deprive the seeds of oxygen.
I know the frustration: I am still using old school (paper towels and drawer in the fridge), it works great for some, but not for others. One cross I had high hopes for was not germinating like the others. I decided to extract the embryos to see if I could get them growin (which had worked for a couple of other crosses). Anway about the time I got to getting them out of the little brown sack they just didn’t want to come and would fall to pieces on me. I should have been smart and stopped while I was ahead, but sometimes persistence grows over into stubbornness. I manage to mangle each of the embryos. I did save some of the better pieces and may get one or two to grow, but my own work frustrated me.
I’ve tried lots of things over the years (but I’ve never used serious biocides), but I have by far had my best and most consistent results from using a simple organic mixture of peat moss and composted manure for stratifying and germinating my rose seeds. Peat moss and sterilized media by themselves have too often allowed pathogens to destroy my rose seeds and seedlings, but a mixture that intentionally includes beneficial and (probably) pathogenic organisms in some sort of quasi-natural balance has rarely given me serious difficulties. My success using peat or sterilized media by themselves was always very hit or miss by comparison.
Moisture level during stratification is a definite concern, so if the mixture is too wet I’ll add more fresh medium until it has a “moist cake” feel to it. If it’s still just slightly too moist and I’ve had enough of trying to adjust it, I make sure to fluff it well before refrigerating so that there’s plenty of air close to the seeds.
I’m not sure what the pH of activated carbon is, but it seems to me that there is at least possibility that it is fairly alkaline, and in that case it might not sufficiently suppress pathogens–assuming it doesn’t have some negative effects on the seeds itself (think about what lye does to cod proteins in the making of lutefisk…). I probably wouldn’t choose pure activated carbon as a long-term stratification medium, but it might be worth using in a temporary soak at some point or as a minor component of a blended stratification medium. It probably wouldn’t do much harm that way, and might just help to absorb or neutralize some germination inhibitors.
Is there a way that you can simplify your processes? I believe in simplicity. Perhaps as an experiment take 50% (or another number that makes sense to you) and cold stratify them already planted in an unheated nursery when the outdoor temperatures warm to “refrigerator-ish”. I know I’m only running with a year and half of experience, a mild climate, and low numbers at about 1000 seeds the first year, but I planted them all because I did not want to do the whole transplant thing excessively. I soaked in 1 part bleach to 5 parts water for about minute. I planted in 1/3 vermiculite, 1/3 peat moss and 1/3 potting soil. My refrigerator-ish temperature here is December so that is when I planted. Plus the outdoors gives a little more fluctuation that might help with germination? I’m blabbing too, but am hoping you hang in there.
I know what is being discussed is mostly stratification, but if low germination rates are the concern, what other factors (variables) are at play? I’ve read from others on here that different pollen parents will effect various things like size of seed, length of time to germination, etc. Does that include effecting rate of germination? Have any of you experienced a great rate of fluctuation in some of your seed parents based upon which variety you match them with in terms of % of germination.
I was thinking of something I read (I believe it was Paul Barden wrote) about how important it is to choose parents that have high percentage of germination, speaking of the seed parent. Still trying to work that out in my own program, especially with the challenges of cold hardiness.
Although I am still enjoying reading your approaches to stratification and the different methods tested!
I wish I had the resources and self-discipline to do some experimenting.
I fear I’m the one who planted the seed, so to speak, on charcoal. I mentioned that, many years ago, I had received seed from Joan Monteith in media in which she had added charcoal as an experiment. She was quite surprised when I reported that the near-species-from-colder-climate seeds were sprouting when I received them. Thinking too of the benefits of bio-char used for crops, and the research on smoke, etc, I figured it all might indicate a worthwhile experiment to try some charcoal in the germination media.
I shared my thoughts last year, and someone (was it Karl?) cited studies / info on the use thereof for other plant seeds, which contributed to my enthusiasm.
I did a heavy charcoal medium last year. Some 5 year old dried rugosas and other older cold-climate seeds exceeded my expectations (and I have to say, I have no comparisons of other media) and germinated very well and rather quickly – Probably more a function of age than media, I’m guessing. Other seeds didn’t do as well, and after a few months, the medium turned to a cake. No comparisons to other media. (I had my fridge on the cusp of freezing, evidently, and found some seeds had germinated and froze, but overall, I would say my germination rate was poorer than it should have been for the warm-weather seeds. Without comparisons of other media, I cannot make any generalizations.)
Hardheaded as I am, I haven’t abandoned the concept. This year, my media is largely peat moss and builders sand, but with some less finely crushed charcoal pieces in it.
Paper towels always seemed to invite mold for me, which peat theoretically suppresses. Peat is slightly acidic while charcoal can be extremely alkaline. I suspect different seeds from different species might react better to different media. Mine is not a good way to go about trialing new media.
I think Don’s advice on not overthinking stuff is probably best.
Thank you, Henry!
(Did I get Kuska and Karl mixed up in my mind? My apologies to both of you if so.)
Is there a lot of info on there on beneficial microbes and seed germinations as well?
Indeed, don’t we all get frustrated with ourselves from time time! Okay, my worst blunder was having used the tomato juice method and it being 100% effective at killing my entire seed crop! On the other hand, I’ve had excellent results with calcium nitrate, last year I was overwhelmed with wave after wave of vigorous germination. Oh, but, I should mention the year prior when I used a tad too much, you guessed it, I had no seedling to show for! The use of calcium nitrate has been much discussed in the past, so I won’t go on regards to concentration. Besides, I go about it in my own manner and apply what is probably equivalent to half of a pea sized amount mixed into one cup of stratification mix, it’s potent stuff, don’t overdo it! I do not recommend anyone follow my rather non precise measuring method.
As for the moisture level of the stratification medium, if you can squeeze water out of it, it’s too wet! As a note, I generally work with smaller seed numbers and the baggie method.
I’m still opening a few seeds to check the embryos. It seems like when I get a firm embryo, the radicle tip is brown. See photo. In your embryo rescue protocols you rail on the sensitivity of that spot, so I wanted to ask your opinion of embryos that look like the one in the photo.
I would hydrate it and strip the rest of the testa but things don’t look promising. If the radical tip is black upon hydration then toss it.
Don- good news! I just poked the seed pictured above into a germination tray, just as it was with half the achene, and today I see it has germinated. All is not lost.
By the way, thanks so much to everyone who posted here. I have yet to digest all of the articles and info.
Replying to Sarah: I know I should keep things simple, but unfortunately it is in my nature to make them as complex as possible. I will probably eventually settle into a fairly simple method. Your outdoor stratification methods are not possible for me here in northern MN, unfortunately.
To continue my overly complicated methods, I just ordered some Triathlon BA, which is a beneficial Bacillus bacteria. Now I’m planning to mix that up with some Rootshield (a beneficial fungus, Trichoderma something). Maybe throw some peat in there or calcium nitrate and possibly nutrients for the microbes (molasses?) and let it bubble at warm room temps using a fish tank aerator overnight to activate the microbes. Then I’ll dunk the seeds in that before sowing them and returning the seedling flats to cold temps until I can pull them out in the spring. This will be wonderful.
Who are the lucky parents?
I thought I’d post a pic of the blossoms of the embryo shown earlier in this thread. It’s fun to have a picture of the embryo and the first (maybe second) blossom.
This pic was taken June 11th, and the seedling is now planted out in the field somewhere…it is not blooming so I don’t even know which one it is.