They are planted outside and were frost bit. Will they come back if I cut them to ground level?
Do I Cut Them to the Ground When They Are Frost Bit
Somewhere along the line we lost the info about what "they" are. So, generally speaking, if you have a winter hardy plant, you can cut it back when it freezes, and cover with 4 or 5" of mulch - chopped dry leaves, straw, or pine boughs work well - as protection. If your plant was a tropical, it should have been brought inside for the winter; if the leaves have been hit by frost, you still have time to dig up the roots, put into a pot, and store in a darkish and cool place safe from freezing. If you can't bring it in, you can try cutting it back and mulching, and hope for the best. Some sub-tropicals can survive, some can't. If you can send us the name or names of the plant or plants you're wondering about, we may be able to give you better instructions.