I wouldn't mulch them. Mulch keeps the soil cooler which is a major downside when planting warm weather crops. If possible I would throw a double layer of row cover over the plants instead. Or if you can make some cloches to cover the plants by cutting off the bottoms of pop bottles, milk jugs, or juice bottles that would also work.

Rodney

i just covered them with plastic nursery pots. Was wondering how long they can stay under them without light.

It seems a few weeks early for peppers to be in the ground up there. I'm not putting mine out until this weekend.

I'd uncover them when the temps get above 45 especially if the sun is out.