Hard to see how a sheet could protect agains a very hard freeze.

I hope the poster from eastern MA successfully protected the viburnums against the nasty freezing temps.

V. carlesii and 'Mohawk' can indeed cross pollinate - V. carlesii is one of the parents of 'Mohawk'. As long as they overlap in bloom time and there are pollinating insects in action, you should be rewarded with some fruit set on these plants.

Thanks guys. I put a sheet and an old quilt over the cage. Don't know how effective it was - the wind was really strong and was blowing the covers around along with the rocks I tried to anchor them with.

The buds look pretty much the same to my eye - time will tell. My Mohawk unfortunately only has one bud. I moved it last year and it had taken about 3 years to get any buds in its original spot. At least I'll see if they open at the same time, though this year is so crazy.