I leave mine in the ground now - 2 years running - and so far only a few are showing foliage coming through with many more still shy. The new ones, planted in pots in the polytunnel, are only a bit further ahead.
I think you should be OK but it has been unusually cold here at night and we still have the Ice Saints to come in mid May so be cautious and check your forecast for wind chil as well as actual frost.