No, they will be fine. If you have a hard freeze they may lay down and look limp until thawed, but will straighten back up undamaged when the air warms again.

I've had some blooming for more than a month - we had several inches of snow followed by an ice storm the next day last week....it was a very slow thaw. Everything finally melted as of yesterday and oriental hybrids and niger, nigercors look unphased today.

Thanks morz8

Mine started early this year as weel. As other poster says don't wory they will come through whatever comes at them. Just enjoy them, harvest the seed and make others happy with it.