Studies to determine the length of time and the conditions needed for successful stratification are common. Many types of seed have been studies extensively and conditions are well determined. Some rarer types may not have had much study. For the most part, those stratification requirements you see are probably based on one of those studies. If 5% of some type of seed germinates without stratification, 20% germinates after 2 months,......and 95% germinate after 4 months, you will probably see recommendations for 120 day stratification. In some cases, the lengths may be guesses. If seeds require stratification and you don't provide sufficient time for that process, much of the seed will not undergo the physical and chemical changes necessary to break dormancy.

That could work. I'll share my thought/experience in case it could be of some use to you or anyone else who visits this forum. One option would be to sow seeds in a small raised bed over the winter and then transplant the seedlings as they come up in the spring into the plug trays or directly where you want them to grow. Personally I like to start seeds in a flat or directly in the garden and then move the seedlings to pots as I get more uniform results that way. When starting the seeds in plugs you can end up with a lot of empty cells if the germination rate is low. With flats you can sow hundreds of seeds and only keep the ones you need. I have had a few species where only 1-5% were viable, so if they had been started in cells or pots it would have been a bust. Most grasses can be kept dry in the fridge until ready to plant out in the spring or early summer. For some species germination rates may be a little higher if given cold stratification and some like sweet grass require it. Wrapping them up and putting them in the shed might be problematic if the seeds start germinating early. I start a lot of native seeds indoors in pots for planting out in the spring. I do the stratification on moistened paper towel placed in little clear plastic bags and put those in the crisper. After 60 days or so I check them occasionally for germination. If the seed is really small it can be difficult to get them off the paper towel but it can be done with a spray bottle onto a white plate (so you can see them). This year I had seeds stratifying through late spring and planted some out directly. Some of the species that prefer full sun perform best if sown directly into the garden.

I do check with Clothier's data on seed germination, it is helpful. A method that I came up with myself and use for germinating seed of prairie wiildflowers and grasses is to cover the seed once it is sown with a coarser perlite rather than a peat based germ mix which seems to smother the seed. This method is used for seed that requires a covering, some seeds need to remain uncovered and exposed to light for germination. I found that Sporobolus heterolepis (Prairie Dropseed) doesn't germinate at all when lightly covered with a peat based media - I got a few to germ that were left uncovered but I get high germ when the seed is lightly and evenly covered with perlite after it is sown. This tells me that prairie species need more gas exchange or exposure to the air while at the same time being covered so the seed is protected and does not dry out. I wouldn't worry too much about your seed germinating early in the fridge, I have Dictamnus albus and eryngium sprouting now in the seed trays that are in my refrigerator - the mice kept getting them in my garage - the cold temps will keep them from growing much and they will be taken out of the fridge in late March or early April to go out into a cold greenhouse to continue growing. Keep in mind that seed that requires stratification for germination can not be hurried along with warm temps! We aren't growing marigolds or petunias here. If you see no activity after you might expect to see signs of life, keep the seed colder longer rather than warming them up - most seeds will start to sprout while still chilled and germ best while at cool temperatures. Again, good luck! I wanted to add that some varieties that require stratification do only start to 'wake up' and grow once the temps warm up, like morz8 said - but not too warm - temps in the low 60's are better than say mid 70 or 80 degrees. Try to avoid quick extremes and no need for additives like wood ash or innoculants for germination - I've never used GA-3 myself and don't really see a need for it. There is no secret incantation or method that will make this process go much faster, it is one of those things that takes time. 'Tricky' things - violet species for example - germinate for me better when they are placed in a coldframe outside because the rain and snow are washing out the germination inhibitors that keep the seed from growing at the wrong time. That is my educated guess. I remember that when I grew Callirhoe involucrata from seed the germination was very erratic, seedlings slowly germinating in an outdoor seed bed for more than three years! This post was edited by jebfarm on Sun, Dec 28, 14 at 13:58

Found one study that showed a lower germination rate for O robusta when scarified mechanically: http://jpacd.org/downloads/Vol12/14-JLFloresJPACD12.pdf They didn't cold stratify at all, and had 23% germination. So, maybe I won't test mechanical scarification.