From what I've seen, just moisten soil and lay seed on top and barely push into media with seed half in soil half out.

Thanks, I appreciate the advice. I do have them halfway into the surface. But I was asking about container depth.

it has to be large enough for the roots to grow freely. the roots are key here. a four inch pot will work for awhile, i would think. no soil. a gritty mix will suffice. make sure your pot has SUPERIOR drainage. soil slows that down.

check out this link for gritty mix instructions

Thanks, I bookmarked the gritty mix instructions. I had already potted them up. Right now I have them in cups--the first one to sprout I moved into a styrofoam cup and the later ones I put in plastic ones that were a bit taller. I've got them in a (soil-less) seed starting mix that I mixed with extra pearlite, and cut holes in the sides of the cups for extra ventilation because I'd heard some people grow them in orchid pots. They seem happy enough. I managed to get seven out of eight seeds of assorted varieties to sprout, and I innoculated the seedlings with Great White, I don't know if that helped or I was just lucky that they're doing well. The one in the styrofoam cup has about three inches of soil under it, maybe a bit more, which is about the same as it would have in a four-inch pot. I hesitate to repot it when it's only got one leaf because I don't want to risk damaging it. I just hope that's enough room. I found one video on YouTube which made it sound like if the first roots hit the bottom of the pot the plant will keel over dead, which I suspect is exaggeration but which worries me.

watch the clear sided container. it can cause issues. watch for algae growth, and repot into another container should that occur.