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.

I normally don't put these out until mid-May and just plant them directly in the soil. Haven't been surface sowing, though, but they seem to come up OK even if lightly covered. These are great butterfly plants, I get tons of swallowtails all season and monarchs later in the summer. After that the goldfinches eat the seeds. Larry

Have you had a look over on Winter Sowing for an easy low tech way of sowing perennials outdoors over winter? Very simple and fool proof. Here is a link that might be useful: Winter Sowing Forum

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