Hello! I collected the pollen from my chosen pollen parents and had some thoughts.
How long will my pollen be viable (or what do you do) if it’s not frozen?
Can you put pollen in the fridge and if so how long can I keep it in the fridge?
Once you take pollen out of a freezer (or fridge) how long do you let it thaw for?
Do people typically do one flowers worth of pollen per jar or more?
If you get a jar with pollen out to use, can you refreeze it?
Thanks for any help you can give me
How long your pollen will remain viable will depend highly upon the temperature and humidity you store it under. I am fortunate to live along the Central California Coast. We’re nine miles from the Pacific over flat agriculture fields so the marine influence is intense. We get all the fog and “refrigerated” air the ocean can muster. Evenings are very damp and days get rather arid. The house remains in the mid to low sixties by itself and much of the time, the patio slider remains open with a “magic screen” for the dogs all day long while we’re home. I harvest my pollen from the first blooms into nearly the end of summer (which arrives here in September) and pollinate most of the year because the weather permits it. The pollens remain on sheets of paper in the formal living and dining rooms where there is no chance of wind, a/c, people nor animals knocking or blowing it off the paper or furniture. Under these conditions, I obtain obvious crosses from it the entire season. If it wasn’t possible to continually add to the pile, I don’t know if it would have been as easy to raise R. Minutifolia hybrids as it has been. Right now, there are several dozen sheets of paper with varying amounts of drying anthers on them right now. When I wish to use it, I take a clean glass baby food jar and dump some of the material in it to take out and pollinate the appropriate flowers with. Afterwards, I pour the material back on to the sheet and put the jar on the paper with it so the next time it is the one used for that variety. If you can approximate those types of conditions, you may well be able to replicate my results. Otherwise, you may need to freeze the pollen to maintain freshness. But, under these conditions, it appears to remain viable for several months, at least, and possibly longer. I’ve not retained it from one year to the next due to the pressure to “please clean up those rooms so I can dust and vacuum!”. Yup, I’m married to a saint!
James, there is a lot of good information in this recent post:
But in a nutshell, viability goes down very quickly at room temps after the pollen is dried, and keeping it at the lowest freezer temp you can muster will prolong viability the best. I’m very small time, and use small cheap cosmetics jars (Amazon) for every flower I harvest, although it might hold 2 or 3 flowers worth of undried anthers. I dry 24 hours, or until the pollen bursts, and then either use immediately or freeze. These jars are also just the right size to wrap an index finger around, while holding tweezers or a brush in the other.
https://www.amazon.com/dp/B00TT70OME?psc=1&ref=ppx_yo2ov_dt_b_product_details
Thank you both! Lee_hull do you have to wait to use the pollen after you have frozen it, or can you take it out and use it immediately?
Roseseek your living situation sounds pretty ideal for breeding!
It is very important that you wait at least half an hour after freezing the pollen before opening the container, jar etc. If the container is opened too soon, the warmer outside air, which contains more water vapor, will reach the cold surface of the container contents and cause condensation which makes the pollen moist and unusable. Another hint from my own experience: plastic vessels are therefore better than glass.
Okay amazing, does putting them in the fridge do anything?
I discard pollen after 3 days. I write down the day I collect it and three days later i hope for new pollen. When I cool it in the fridge 3 degrees celsius I time 7 days and frozen a month.
I have actually never stored pollen in the refrigerator. Therefore, I can not report anything about this method. As much as I can say, I try to use fresh pollen within the first two days or freeze it until the time comes to use it. I have also occasionally thawed and frozen pollen under this rule for several times. It didn’t seem to be a detriment. But the principle is the same. By using refrigerated pollen I would also wait a bit before opening the jar, because the temperature difference is large enough for condensation.
One nice thing about these small jars is that they come from 0F to room temperature very quickly. No real thermal mass. I’ll wait 10 minutes, but you can warm them in your hand in less than a minute if you want. You’ll be ok as long as the jar temp is above the dew point before you open it.
Also, concerning refrigeration, it isn’t as effective as freezing…here’s the takeaway from the study (30 days): “ Analysis of the pollen germination rate showed that the standard type was 21.2–30.2% at the storage temperature of −72 °C, 20.4–28.7% at −20 °C, 11.1–19.4% at 0 °C, and 2.1–10.4% at 26 °C”
Wide variations, but viability definitely follows some standard curve related to temperature. Colder is better.
I haven’t used frozen pollen, but might try sometime. I always have pollen for crosses, so keep it fresh. I like to use pollen either later in the day of collection or on the following day.
When I have collected blooms from an offsite location, I will store them in the refrigerator for up to a week and collect viable pollen from them during that time (taking a couple of blooms out of the refrigerator each day to remove the pollen). When the blooms are collected, I try to collect blooms that would be expected to open in 1 to 2 days outside so that they are mature enough to develop viable pollen while refrigerated.
I use quite a bit of frozen pollen. A primary benefit is that freezing allows you do develop a pollen “library” that can be used even if the pollen and seed parents do not necessarily bloom in direct sequence. Here, flowers are scarce in summer, but relatively plentiful in spring and fall. I will frequently use and re-freeze pollen for a few pollinations, although I keep my individual pollen samples small enough that they are usually just about spent after a few rounds of application anyway–usually one to several flowers, depending on how many are available within a short period of time, or the expected pollen yield of each flower. I use pieces of aluminum foil (heavy duty whenever possible) to dry the anthers, after which I fold it into a sort of envelope and slip it into small, transparent zippered plastic bags for freezing (inside of larger zippered freezer bags for added protection and to help keep things together). The foil and plastic bags allow most of the air to be eliminated quickly, and in combination those layers help to prevent damage during freezing. It also takes up relatively little freezer space. The metal foil allows for rapid warming of each bag by hand after retrieval from the deep freezer, prior to opening the zipper, which is especially important in my frequently warm, humid growing seasons. It’s easy enough to write the name of the pollen parent and the date on the foil using a permanent marker–I usually jot down information on the inside of the foil right away, and then again on the outside of the foil after folding. The foil can be shaped into a cup as needed to help prevent wind from blowing the pollen away, and it’s simple to swipe the pollen off using a fingertip and to see how much remains (it’s best to keep the shiny side inward for freezing purposes and for better pollen visibility). The cupped foil is usually sturdy enough to allow the dry anthers to be flicked with a finger to release additional pollen, especially useful for those situations where pollen is scarce and every grain matters.
Stefan
Thank you everyone for your tips. How many of you apply pollen more than once? If so, how far apart do you wait between applications?
Usually if I’m doing it, it will be once a day, in the morning, if possible. I figure that since it’s when the bees are most actively gathering pollen, it should also be the time that the stigmas are most receptive.
Stefan
Generally, I pollinate only 1 x. For particularly difficult or more distant crossings I pollinate 2 or even 3 times. With roses, where the ancestors are not known to me, I also pollinate 2-3 times. Often it is also advisable using mixed pollen to achieve a higher hit ratio. In very special cases, nature simply did it better, see example of my OP- Ispahan seedling.
How long can you store frozen pollen. I am freezing stuff now for next season… Will that still work?
Yes, it will definitely work by the next season and beyond. The most important thing is that the pollen is absolutely dry. There must be no residual moisture. If you have a lot of pollen from one variety, it is advisable to divide the amount into several containers so that it dries better. Closed Silica Gel packs are also recommended. It is essential that the cold chain is never interrupted to ensure that the pollen does not thaw and freeze again. In case it does happen, e.g. due to a power failure or the pollen was still too damp it is clearly visible. The pollen is then sticky, dark, even mouldy and must be discarded.
Thank you, I have been using silica gel beads recently, very effective
I freeze, thaw, refreeze, and rethaw pollen all of the time! The most crucial thing is that it is not exposed to humidity or moisture while it is still cold. I dry mine in the open, package it in aluminum foil and then inside small sealed bags, which then go into larger sealed bags in a deep chest freezer. When they come out, they must be warmed before opening so that humidity doesn’t reach anything cold inside the bag. I don’t use silica gel and haven’t had any problems.
Stefan
