When do you collect pollen and how do you dry & store it? I always am looking for a better way to do this.

I try to collect the pollen before the anthers open and place them in a labeled open plastic container for drying. I dry the pollen at room temperature for several days before freezing. I put a cap on the plastic containers and then put them in a Ziploc freezer in the freezer. If I am going to be working with the pollen I will keep it in the refrigerator and only take it out for pollinations.

I have used paper & glassine envelopes as well as foil in the past. I like the idea of packaging dried pollen in foil in smaller quantities in the freezer so I don't need to take out all of a pollen lot each time I use it. This is something I want to try this season (several lots of smaller quantities rather than one container holding all the pollen of one lily).

Do you store the pollen with the anther or separate? Do you dry it for a certain amount of time?

Charlie Kroell had an interesting method where he would dry the anthers over night under a warm incandescent lamp and then he would separate the pollen from the anther using a screener and only store the pollen. I have never tried this but it would seem to be effective.

Any other variations out there?

I have been using foil the last couple of years and making multiple packets of smaller quantities as you are musing about. I like the method and will continue to use it. Prior to that I have used microcentrifuge tubes where the pollen is separated from the anther by shaking it off using a vibrating massager. This method was a bit iffy because sometimes the pollen just doesn't want to come off or it will come off then stick back on.

The foil packets of each pollen type go into a small ziplock bag with a label and how many packets are in it. This gives me at a glance how much pollen I have of that type. These small baggies are sorted and stored by division in larger baggies.

The screening process sounds cumbersome. You would need a lot of screen to prevent cross contamination, right? Or clean it with alcohol between screening each type of pollen.

In 2015 I got fancy and colored coded the baggies to ID the division to make the packet search quicker. Asiatic tangos got a separate color code as I didn't want to dig through the main Asiatic baggie looking for tango pollen.

Connie - thanks for sharing your method! I agree that screening seems unnecessary and adds potential complications like cross contamination. The recommendation is to hit the sieve with alcohol between cultivars to kill any pollen contamination from the previous lot, but not sure that I understand the benefit of separating the pollen from the anther prior to storage.

How do you dry your pollen? Any special temperature or length of time?

I have dried pollen in the refrigerator too, but I am never sure how dry is dry enough whether on the counter top or in the fridge. I tend to err on the side of too dry as opposed to leaving too wet.

I simply dry at ambient temperature for at least four days. Sometimes I lose track and some pollen goes longer. Generally if I'm not in too big of a hurry I'll write on the pollen packet the number of days it was dried. Some have gone as long as nine days but I have just recently begun tracking this so can't relate results.

The last couple of seasons I have left the pollen on the anther, you just want to make sure it is dry. I assume it is after the minimum four days.

The nice thing about using foil or even the centrifuge tubes is that they are easy to open and do a quick dip with a Q-tip then close up again.

My dining table is pretty much dedicated to drying pollen and labeling and pretty much every thing else plants, even potting up some things (e.g. veggie starts). I read somewhere that it is healthier to eat standing up !

I have found that if I try to remove the pollen from the anther, I lose more than I save. I will take the anthers, preferably unopened so I can grab them with my fingers instead of tweezers and put them into the small paper Dixie cup (really cheap and easy to dispose of). I then write the plant name and date on it and dry up to a week on the kitchen table. I will add additional anthers as necessary as more flowers bloom depending on how much I want to save. Then after 4-10 days (depending when I get around to it) I slide the anthers into a paper coin envelope and throw in the freezer. I also write the name and year pollen collected on the coin envelope. The Dixie cups are also great at the end of the year when I take pods of and want them to dry a little more, I put them in to dry. If they crack and seed spill out they're contained to the Dixie cup. I have never had a contamination issue using this method and the pollen seems to stay fertile for me. I take the envelope out to do a few pollinations and then they go right back in the freezer. I try not to freeze and thaw to many times before chucking the pollen.

Most what I know, I have learned from Connie in this regard. I dry pollen on foil at room temperature (75-77 degrees F generally) , labeled for 4 days before freezing. I use a toothpick to get the pollen off of the anthers into a homemade small wax paper envelope. I have had great success with freezing and keeping for at least a year in top freezer of family refrigerator. I store the wax paper labeled with name and freeze date in a manilla envelope inside the freezer.

I've become really good at 'plucking pollen' by guiding the anther into a test tube (12.5 X 75mm) and trapping it there with my index finger, then a slight pullback and the anther drops to the bottom of the tube. I usually can get 6 to 12 anthers per tube. I'll then tear off a little cotton from a cotton ball to provide a temporary seal. Once back at the house, the contents will be dumped into a Dixie cup to dry for 5 to 10 days in a cool well ventilated dark room (low fan), then put back into it's original test tube for freeze storage. I keep pollen on a 5 year rotation. Also, I now use plastic caps on the test tube storage samples rather than the cotton plug.

Thanks everyone for sharing your techniques. Very helpful! I have used Dixie cups for collecting hosta seed but for some reason never put them into use for pollen - that will change this year. I too have done similar to Joe with the add new anthers to previous container of drying pollen of same cultivar. I think this year I will just use more Dixie cups and keep it separate and package it in smaller foil packs after dry. My wife & kids hate this time of year as I have pollen scattered around in various little plastic containers that are too easy to bump and spill.

I have lots of test tubes but they tend to be full of plants or contaminated media waiting to be washed out. The plastic test tubes are much cheaper especially if you don't need to autoclave them but I think I will be going with foil as the final storage media.

I haven't done much pollen collecting, more because of poor planning than anything.

Until last year I've never had air conditioning, and knowing about relative humidity and dew points were paramount in keeping my house comfortable through the hot summers. Just because the air is cooler outside at night doesn't mean it's time to open the windows to cool the house down, for example. "It's not the heat, it's the humidity" is a time honored axiom. So I have always been cognizant of this relationship, and apply it to many situations (as everyone should ).

A case in point, this discussion. Anytime the temperature drops (i.e. ambient temp to fridge or freezer) the relative humidity rises for any given sealed volume of air. Is this important for pollen storage? Above freezing, certainly. If you put a sealed vial of pollen from 70F, 30% relative humidity into a fridge at 40F, the relative humidity inside the vile becomes 88%! This cannot be a good thing, and illustrates a case in favor of unsealed storage. In previous years, Lorn has mentioned his use of cotton as stoppers for his vials, and I immediately thought "what a great way to solve this problem of high humidity with lowering temperatures."

But below freezing, I don't think humidity matters because ice crystals don't act like liquid water or vapor.

Comments?

Rick - great questions. If I have pollen in the fridge I put it there uncapped to allow it to continue to dry out. I wouldn't recommend putting freshly collected pollen in the fridge and capping it. I do believe leaving it open that it will slowly dry out - more slowly than at ambient temps.

The moisture level of the pollen is in equilibrium with the moisture of the air around it. If the air has higher moisture levels it will push some moisture into the pollen. If the air is dryer than the pollen it will pull some moisture from the pollen. I expect there is a range of moisture in the pollen for optimum pollen longevity just like there is temperature. I have been told that pollen that is properly dried and frozen can last many years and have experience to support this. I believe if you don't seal the moisture in for frozen pollen that it will dry out too much and lose ability to germinate. I base this on my experience with seeds - they too have a moisture range where they will maintain the highest germination percentage. If the seed gets too moist or too dry, it will kill the embryo in the seed. I presume that pollen behaves the same way but have not researched it.

Based on these assumptions I set up some working boundaries. If I am going to use the pollen in the next week, I store it on the counter open to atmosphere. If I am going to use it after one week but before one month I will store it in the fridge open to the air. If I am not going to use it for over a month, I would ensure it is dry and freeze it in an air-tight container. I don't have all the science to back this up - this is just how I approach this. I expect this is different for different genus and even expect some difference with tetraploids vs. diploids.

I am interested to hear with others have to say on these questions. Thanks for bringing this up!

Your working boundaries seem reasonable, Patrick. Indeed, things do continue to dry while frozen if not sealed, though far more slowly. That would be the freezer burn we see on food. And to be clear, I was not implying that anyone was sealing pollen incorrectly, just that it is a factor that should be considered.

I disagree on one point: that stuff dries more slowly in the fridge than at ambient temps. In fact it is just the opposite because the relative humidity inside a fridge is significantly lower than outside the fridge. Every florist who uses a fridge to store their flowers and bouquets knows that a food fridge won't cut it. The flowers dry out. A florist's fridge has added moisture to compensate for the humidity lost during normal operation of any refrigerating unit. The air is cooled to a significantly lower temperature than what the fridge temp is set at, so it can adequately cool the air already in the fridge that it mixes with. Lower temperature air means it holds less moisture, and as it mixes with the warmer air in the fridge to cool it down, the relative humidity becomes even less as the temp rises to the recommended fridge setting. Things dry out faster.

I wouldn't be surprised if optimal storage moisture differs within even the Lilium genus, temperate vs. sub-tropical, for instance.
I would be interested to hear your thoughts on diploid versus tetraploid on this subject, too.

Rick - one of the main reasons I was putting the pollen in the fridge was to dry it. As I was thinking through this, it wasn't clear how much dryer the fridge would be. I haven't seen a fridge with a moisture drain and it is not clear to me how it purges the excess moisture as it cools air down after you have opened and closed the door. Either way I believe the cool temps help enable longer pollen viability.

As for tetra vs. diploid pollen - I have heard that tetra pollen does not store well. As a result I stopped trying to store it for a few years but have since started again as I spoke with folks that do it successfully. I think it is a cultivar dependent thing and probably only shows if the viability of the pollen is really low to begin with?

I hadn't thought about the no moisture drain. Not sure how that works, then. Maybe its vapor pressure equalizing?

Leftwood said:I hadn't thought about the no moisture drain. Not sure how that works, then. Maybe its vapor pressure equalizing?

No idea where the excess moisture goes - guess I need to read up on that. One thing is for sure - it is dry. In my fridge, if you put pizza away in the cardboard box it dries out fairly quickly. There must be some sort of moisture purge cycle - I am sure it is a little different when you have a combined fridge freezer vs. fridge only. We have 3 fridges and all three are combined. The oldest one that I need to get rid of ices up so it is clear what it happening with this one.

Just got home from Gordon Foods. I picked up a package of 200 x 3/4 oz plastic sauce containers for pollen. It was just under $3.50 out the door. I have been using different size plastic sauce containers and the clear plastic food tubs from there for years as they come in a variety of sizes and are a good price for the volume. You can also buy snap on lids if needed which has been very useful at times.

Patrick, the plastic containers don't take up too much room for you?

Patrick, photo of the containers please. I use 2" plastic culture dishes because they are what I happen to have and they work well. I don't enclose them, the lids make for another container to dry pollen.

Joebass said:Patrick, the plastic containers don't take up too much room for you?

Joe - they are smaller than Dixie cups. I have used larger ones of the same style and smaller ones of a different type of container in the past. I like these as they are wider base and I am less likely to tip them over by accident. The skinny ones I have of a different style I drilled holes in a piece of 2x4 to hold them and keep them from tipping. These work well for carrying pollen to the garden but not as well for drying in my opinion. The skinny ones I would re-use but the ones from GF would be more of the disposable type. I will post some pics later.

pardalinum said:Patrick, photo of the containers please. I use 2" plastic culture dishes because they are what I happen to have and they work well. I don't enclose them, the lids make for another container to dry pollen.

Connie - these are about 1 1/2" diameter by about 1" tall (my estimate from memory). I will take a picture tonight and post. They seem like a good size to hold 6 to 12 anthers of a large flowered lily for drying. The mart album pollen I just put in them looks dinky...

Just because it's what I had already, I use a compartmentalized tray so the cups don't tip.

Thanks Rick for sharing the picture of your tray. I have been looking for something like this.

Here is a picture of the different containers.


On the left is the containers I have been using most recently. The have a plastic snap lid that I put on after the pollen is dry and behind it is the 2x4 board I drilled with holes to hold the containers. These containers are ~3/4" diameter x 1 1/2" tall. I use a paper sticker label on the outside to mark what is in it. They are too narrow to hold larger anthers and are too easily tipped over. They work perfectly for hosta pollen that is much smaller anthers.

Next to it on the right is a Dixie Cup I snagged from my kids bathroom for size reference.

The next two on the right are bead containers I picked up an Walmart a few years back - they have threaded caps - 2 different sizes. I have left the tops off during drying and then cap when I put these in the freezer inside ziplock bags. I use paper sticker label on the outside to mark what pollen is in it. I have cleaned with alcohol to re-use.

The last ones on the far right is the new 3/4 oz sauce containers. The are about 2" across and 1" tall. They are like a short plastic Dixie cup. I write directly on these what is in them. You can buy lids for these separately but I don't intend to put lids on them. My plan is to dry the pollen in these and then transition to foil packets labeled with masking tape for freezer storage.

That is my plan for now - it will likely change as I am always tweaking things looking for a better way. I would like to find a tray to hold the containers more securely. I might use a multi-cell plant tray and put one cup in each cell? I have tried fishing lure boxes and bead containers but I don't really like how either of these have worked for me.