Drying out helps to maintain viability---to a point. I think it is a combination of things that conspire to bring down germination rates ultimately to zero. I think the most important factors are temperature, moisture, and length of time since harvest---in that order. The moisture factor, I think, is multi-faceted. I put my seeds in Lowes Foods plastic snack bags with a piece of high grade typing paper approximately 1 3/4" by 3" that has the name of the cross written on it. I then place the bags in PAPER lunch bags in the refrigerator (preferably the crisper drawer). If I put more than ten seeds in a bag, or the seeds are too wet to begin with, the seeds do not do well. (This can be especially problematic if the seeds are harvested during a long rainy period). Too much moisture causes premature germination which can be seen by the seed coat splitting---sometimes with a root emerging. Once that occurs, the seed needs to be planted---or it will quickly go downhill and die. Sometimes this can happen without the seed coat splitting---enough moisture to start the process, but not enough to swell the seed to the point of splitting. I think that could reduce the ability of the seed to last a long time. The process of germination is pretty much an all-at-once thing---intended to take advantage of the right conditions in the Spring to maximize the chances of the resulting plant to survive. Another factor is contamination. Bacteria and/or fungus need moisture to thrive. The more the moisture---the more these things conspire against the seed. I always check the seeds a couple weeks after refrigeration. If there is visible moisture in the bag, I take the seeds out, air dry them---then rebag them with a new label, in a new plastic baggie. The purpose of the label is twofold. First--it sops up any extra moisture on the seeds immediately. Second, the high grade typing paper that I use is very white from bleaching--a minute amount of which stays with the paper. The bleach in the paper helps keep bacterial infection down. That, and dryness helps the seeds to last longer. It has an additional effect as well: The tiny, non-visible amount of moisture that it sops up, keeps the seeds in better shape for a longer time---than if they are stored in complete dryness. Refrigeration is drying. Even though they are in a plastic baggie--moisture is lost through the imperfect seal--and also through the plastic itself. I used to place the bags of seeds in another plastic bag for storage. That resulted in too much moisture problems. Placing them in a Paper bag slows the drying down---but at a more even rate than if they were not in a storage bag at all. Keeping the seeds this way has increased germination rates on two year old seeds dramatically. A few years ago I purposefully kept some seeds for three years. I transferred them to the new paper bags with the present year's crop each year---to see how they would do. The fourth year I planted them---and 28% germinated. Now, to be honest, this was seeds from a cross that reliably gave 100% germination if planted the first year. However, 28% after three full years of refrigeration I think is pretty great. I do think that there are differences in germination rates that depend on the cross made---and the pod parent. I have a beautiful pink that was made by Stoeri, but never registered, that I was gifted from a friend who knew him. I produces seeds that have VERY soft, wrinkly, outer shells. These seeds have a extremely high germination rate--if planted soon after harvest. If treated in the method described previously---they shrivel down to tiny wrinkled balls---if they do not rot first. Germination plummets from 100% down to 15% in one year. That is the extreme---but it makes the point that there are individual differences that can influence seed longevity. I am sure that there are many factors involved with seed storage. I have solved only some of them---and not for all seed. Good luck with your seeds this year!
