Hi, 

You will probably want to cut the peonies back to the ground, leaving about 2 inches is fine, as they are floppy plants anyways with their big gorgeous flowers. They will regrow. Doing so now is good. 

Leaving debris is actually good for the garden -providing habitat for overwintering beneficial insects and adding organic material back into the soil as it decomposes. Only leave leaf littler or plant stalks from disease free material. Peonies often get powdery mildew or a leaf spot disease so this year you may want to cut them back after a hard frost and clear away the leaf litter of those. Leaves from fallen trees or other plants would be ok to use. 

You can prune the hydrangea now as well. It looks like a Panicle type hydrangea which bloom on new wood, so trim to a desirable height going down to a leaf node. You can reduce it by about 1/3 if you'd like or you can just take the flower heads off. You can refer to our Hydrangea pruning page for more information and also our pruning shrubs page for techniques. Bypass hand pruners work best for this. 

It looks like you have landscape fabric in the bed and we would suggest you remove it. They are often made of synthetic material containing plastic which adds to waste in our environment, they can deter water from reaching the plant roots, and weed seeds can get embedded in them making it really difficult to pull the weeds. A thick layer of mulch in the bed about 3-4 inches tapering to the root base of plants is good to keep weeds at bay. Weeds will inevitably come either with or without fabric but much easier to dig out when the fabric is not there. 

Let us know if you have further questions. 

Emily