Transplanting Snowdrops

I have been offered over 4000 snowdrops for our local cememtery woodland.
I know they are better transplanted in the green but does that mean you can replant them flowering or not?
Also last year I replanted over 2000 and nopt a lot have come up. The gardener said as some are blind I may have put them in too shallow and I will have to wait for them to rebulb over the next few years.

1. What did I do wrong last year and how do I stop myself doing the same again?

2. Can I move the ones I have been offfered now or after flowering?

3.Any suggestio ns?

 

Or too deep compost maker, three times their height in depth is perfect, you can transplant them whenever "in the green".

 

The point at which the stems of the bulbs you are planting change from White to Green will tell you th depth they were at when lifted - doesn't mean its right, but it may help!

They will probably arrive limp, soak well (several hours) and then water frequently after planting for the first couple of weeks, and then over the next couple of months if we get any dry spells