They take the seed in the fall and place it in the clean sand and put it in their coolers. They reduce the temperature until it gets cold outside (they normally start this in Octoberish after they are done drying). Then, they turn off the cooler and the insulation of the cooler keeps the temperature of the stratification boxes from going below the danger mark (off top of my head I'm thinking about 23 degrees) most normally, I think it will not freeze in the coolers.
Then, in the spring, they move the boxes out of the coolers and allow them to warm naturally...they never add water or cool the seed again artificially. It gets planted in mid August, and cools naturally with the ground.
I think the warm, sudden cold, then warm again, and then natural cooling into winter might be the issue. I think most of our problems, however, is drought.
You might be right on the money there Guy. I always suggest planting 3/4 to 1\" deep. But, seed I've sown by hand in rows then raked over, always had germination issues. I think the more shallow depth caused by raking them in caused this issue.