Well done ! You could keep them sheltered if possible, just to be safe. I've left them out all winter but only because it didn't really matter how many survived. You can shelter them from the worst of the cold in any outdoor space by putting them all together in a box. If you have access to straw or dry leaves you can protect them even more, but don't get too motherly ! (Sun warmed straw can harbour pests.)
A bit of hard weather will not do much damage if they have rooted, but too much water on the roots would be bad for them, such as standing the pots in water. In the spring, watch out for slugs which can undo all your hard work in a day....they love hydrangea bud leaves. Gravel is a good deterrent.
So a box full of well draining gravel then :o).