To be honest, I haven't really stored pollen, other than in the fridge for a few days. But I do read about it, and have sent out dried pollen to a person who instructed me how to do it: pick stamens with ripe anthers and dry inside for 3-5 days, fold in paper or place in small paper envelope, send (in the mail).
I gather that it is even more important not to allow pollen to go through freeze/thaw cycles. Some say once it is frozen and thawed, it should not be refrozen. So if you have a self-defrosting freezer, you may need to take precautions.
Generally speaking for lilies, the stigma is most receptive on the second day of bloom. This is not to say that pollinating on the first day (or sometime after the second day) won't work. It usually does. Lilies are not very finicky in this respect, but do wait until you can detect some stigmatic fluid. If the stigma isn't sticky, the pollen won't adhere well, and the stigma isn't receptive anyway. There are other plants that are very particular, and some I find I need to pollinate at least once a day during the duration to get good seed set. Weather plays an important role in the success of pollination.
I always cover the stigma
before and after hand pollination. Otherwise, you can't really say what the pollen parent is. The whole point of hand pollination is control. For me at least, that's important. Sometimes I may used a mixed pollen, but I still know what is in the mix. Anthers are removed or stamens snapped off of pod parent flower, unless I need the pollen for something else. Otherwise it is just too easy to accidentally self pollinate a flower or get pollen stained fingers that can contaminate other pollinations. (While self polliation won't actually occur with most lilies, other negative outcomes are possible.)
For myself, I do clean pollinations and dirty pollinations. Clean pollinations are when I am usually out in the garden early in the morning (around 5am) in the first hour of light. Most lily flowers are opening then, and you can be sure to cap off the immature pistils before bees and other insects get to them. The object here is to prevent any contamination with unwanted pollens. I'll leave the pistils capped until the next day, if weather cooperates, then pollinate, and recap.
I have a system for this method. My pollen caps begin as tin foil squares.
Capped but unpollinated pistils have tin foil that is merely folded over the stigma once. This also makes them easy to remove without causing any damage to the sex organs.
Stigmas recapped after pollination are fold back over and folded more to make them permanent. And this way I can easily see if a flower has already been pollinated, or if it still needs to be pollinated.
I deal a lot more with species lilies that tend to have more delicate parts than hybrids. So pre-shaping caps, over a pencil for instance, that works fine for larger hybrids just doesn't work for most species.
Dirty pollinations are when I get out in the garden late (say after 6am) to cap. Insect are already quite busy then, and often I can see unwanted pollen already deposited on the stigmas. So I only go to the trouble of pollinating stigmas that seem clean, but still label them "dirty" because there is possible contamination. And yes, I have found by growing out these dirty crosses, that these dirty pollinations usually ARE contaminated.
Of course, timing is relative: if a flower doesn't begin opening until midday, well, there you go....
And there is also the variable of insects themselves. I can tell you that compare to when I moved into my present house 20 years ago, I now have at least 10 times as many insects, and 20 times the diversity. (and I love it!)
