I might have missed it, but I don't see it mentioned anywhere in the thread that the bulb should be planted very close to the surface. If I remember correctly the growing point should be at soil level, or even poking out a little. Or do I have that wrong?
Back in Wisconsin there was a house near us that had a bed of the yellow bungeis, and it was stunning! There must have been about 20 all blooming close together. Wish I knew their secret!