Hello,
I had replied in your other thread regarding UVB. They can go a few weeks without UVB, but during season when they are not brumating I wouldn't advise going longer than a month tops, without UVB, or their calcium levels will begin to fall a bit. They will be ok for a few weeks, but, it is important to remember that they cannot properly absorb calcium & vitamins without UVB exposure, too.
Tracie