We are running three weeks ahead so that pollination season is beginning when I haven’t yet finished germinating embryos from last season. I’m ready for it, though, having stocked up on pollens for use with the first bloomers like moyesii, omiensis and the hulthemias.
Having taken out some Joycie pollen from the freezer to do the first pollinations today, on Sericea, I am now wondering whether to leave out the packet or put it back in the freezer until it is needed again in a week or so.
Has anyone established a best practice for managing frozen pollens?
Thanks, Natalie. I did read that discussion when it occurred but I still have some questions.
The average amateur will, like me, be working with equipment and materials at hand. My freezer can get only get down to -8° F and we leave the auto-defrost cycle turned on so as not to lose track of the waffles and chicke breasts. I could purchase drierite by mail order but silica gel is less dusty, easier to recharge and can be had at the local craft store. My pollen, once dried, goes into 2" x 3" resealable poly-bags rather than micro-centrifuge tubes. The baggies get put into disposable type food container in the freezer.
When the time comes I take the baggie out of the food container, which stays in the freezer so the other pollens do not thaw. After use I put the baggie in the fridge at 4° F but I would stick it back in the freezer if I knew it was the better thing to do.
Do you know of any studies on pollen viability as a function of drying agent, storage temperature/time and repeated freeze/thaw cycles?
Sorry it’s taken so long to respond…I’ve been traveling again!
Personally, I don’t think the type of drying agent you use will make a big difference. As long as it performs it’s function (pulling water away from your pollen) then it shouldn’t matter what brand you use.
For the current season, I actually store the pollen in a fridge/freezer combo that does have the defrost cycle function. It’s just the long term storage that I prefer the non-cycling type of freezer. (And remember, it’s just my opinion. I have no idea if it really affects the quality of pollen or not.)
Let’s see…articles that deal with pollen storage…
S. Gudin, L. Arene and C. Bulard. 1991. ‘Influence of season on rose pollen quality.’ Sexual Plant Reproduction 4:113-117.
Yoshihiro Ueda and Masaki hirata. 1989. ‘Pollen fertility in roses.’ Jap. J. Palynol. 35(2)1-7.
T. Visser, D. P. de Vries, G. W. H. Welles and J. A. M. Scheurink. 1977. ‘Hybrid tea-rose pollen. I. Germination and storage.’ Euphytica 26:721-728.
T. Visser, D. P. de Vries, J. A. M. Scheurink and G. W. H. Welles. 1977. ‘Hybrid tea rose pollen. II. Inheritance of pollen viability.’ Euphytica 26:729-732.
Mary Ann Wohlers, Raul Peimbert and Dennison Morey. 1962. ‘Factors Influencing Seed Production in Hybrid Roses.’ American Rose Annual 47:103-109
I haven’t read most of these in many years and there are a few I have not read at all…so they may not all help you out.
I’m sure there are several more articles out there, these are just the ones I could find without to much research…
Does everyone agree with what was previously discussed in this thread. Is it okay to refreeze pollen after use? Do you need to dry the unused pollen again?
I feel like I’ve noticed that after a certain number of times in and out, like 7-10 times maybe, the pollen becomes less willing to produces grains when I shake the bottle. I’ll then leave the bottle out to dry until the end of the day and sometimes that fixes the problem.
But in general the biggest thing for has been making sure that I’ve fully dried out the pollen initially. So long as I wait until the container reaches equilibrium with the outside temperature before opening, and then put it back in the freezer once I’m done then I’ve been able to reuse the same pollen for months. Although using fresh pollen always seems to have the highest success rate.
For my high priority pollen that I can collect in large quantities, which is basically just r. foliolosa this year, I’ve started storing it in multiple bottles for different seasons. So I’ve got bottles that I’m not opening until this fall, this winter, and next spring, in order to preserve as much viability as possible.
Thank you for the response I have amazingly… until today never refroze pollen so was worried it would ruin it. Good to know that I don’t have to commit to using it when I get it out!
Practically every day during pollination season, I’ll pull a tray out of the freezer containing all the pollen containers I’ve filled that season (when I don’t have have fresh pollen of the cultivar I need). Some containers may get cycled that way more than 30 times, but are not always opened. I have not noticed a great drop-off in viability, but that doesn’t mean there isn’t.
What does everyone use to store the pollen for the season? I know long term people use aluminum foil but if you are taking it in and out is a small plastic lid and cup work? If so do you put the silica pack in the cup with it or put both in a ziplock?
I store mine in old prescription bottles. Easy to shake and see the grains on the bottle and lid, plus they’re airtight. I haven’t felt the need to use silica packs. I’ve only ever lost pollen to moisture when I didn’t dry it out thoroughly enough.
I use small makeup containers. Buy them cheap on Amazon in bulk. I put anthers in them and then leave them open in a small plastic container with desiccant and humidity indicator card for about a day (until they hisp) then close, shake and then put in the freezer
They have been fantastic so far. Small enough to not take up too much space but with a large-enough opening to easily put in anthers (after they’ve been plucked with tweezers) and for a brush to enter to gather pollen.
I place the anthers in there, leave the jar open for a day, then close the lid tightly in room temperature, shake the container to confirm pollen release, and either freeze or refrigerate the pollen.
For refrigerated pollen, I take it out of the fridge and leave it at room temperature for around 15 minutes. Then I open the lid and use it.
For frozen pollen, I take it out of the freezer and leave it at room temperature for about 1 hour. Then I open the lid and use it.
I’ve done the freeze-thaw thing before, but I think this year I’m just gonna fill jars based on a per-pollination need, so I’ll fill multiple jars with the same type of pollen. I’ll take out only what I need to use immediately and then clean/wash the jar as opposed to re-freezing it. I don’t want to deal with doubt over whether the pollen was still good or not, especially because summers here get very humid and I would need to expose the pollen to humidity every time I pollinate, and then wonder if the re-freezing went well or not.
So I’m not dealing with re-freezing.
I do refrigerate, though, because I pollinate the same cross twice a day for 2-3 days, just to ensure that the stigma was receptive at one of those points.
Thanks all for the replies. I’m using those small plastic condiment cups with snap on lids like you get at some fast food joints. I had thought freezing was just for long term so this will be helpful.
See this earlier discussion on pollen storing containers.
If I were to do over again, I personally would get slightly wider jars that I could more easily fill and get my fat fingers into. (I have been known to just shove the whole head of an emasculated clower in to wipe the last remnants onto the stigma. Poor practice admittedly.)
They come in colors too, but I like seeing what is in jar.
