I don't know the extent of the damage but many, many animals and insects nibble on plants.   You could be talking about the bloom being completely gone on the zinnias.  In that case, probably rabbits or deer.  The hydrangea, if there are small holes in the leaves, it could be any of dozens of insects.  If the leaves and/or blooms are being eaten off, it probably is deer.  If down low, then rabbits.  With more information I could give you a more precise answer.  There are repellent sprays that can be used to discourage animal feeding.  They have to be reapplied frequently and, it is suggested, that brands be rotated.