Stefan, how nice for you to go snowdrop-shopping! It looks like a super happening. And very nice to see your snowdrop pictures.
Mariette, you have a very nice seedling! And 'Cowhouse Green' seems to grow well for you. Here it is struggling, and I must move it this year so that I would increase better. Now it has had only one flower for several years. It grows in a dryish shady spot, maybe more sun or more moist would be better?
Jeff, here I haven't noticed a difference in yellows in different pH soil. Our soil is naturally maybe pH 6, someplace less, but I think yellow snowdrops are yellow also in a bed where I have added calcium.