I do not recommend pruning hydrangea or other cold sensitive shrubs in the fall. Pruning always stimulates growth and autumn is when plants need to slip into dormancy. However pruning when the shears are sharp and when a branch is in your way is also a practical way to time a snip here and there. The best time to prune is in late winter or early spring when your plants are starting to wake up from winter. I have had good luck pruning the new Endless Summer hydrangeas anytime of year - this is because they bloom on new growth and pruning off old growth stimulate new growth. Gardening is an art, nature surprises us, experiment a bit and see what happens. Keep growing, Marianne Binetti