How about starting them in a pot? I have some A. christophii in pots that I sink into the soil and that works well for me. They just wouldn't grow straight in the soil!

Otherwise, is the area too damp? Have you tried planting them on a handful of horticultural grit?

Despite being sold in large numbers, it is not a particularly easy one to grow. I have a lot of Alliums and this is one which seems to flower the once and then die off.