Rebloomers like the Endless Summer, Forever & Ever Series are advertised as being hardy to Zone 5, which means they would survive a winter in that zone with nothing more than 3-4" of mulch. The catch is that those hydrangeas develop their first set of flower buds in the July-August time frame and these will not produce blooms consistently because the buds, the stems or both freeze/die out during the winter. That does not harm the plant per se, as new growth will then develop from the crown/base and you will get more flower buds... just later in the year. What you can do if you want blooms earlier is to:

* stop fertilizing by July

* if you have to prune live stems for some reason, prune them no later than by the end of June

* maintain 3-4" of mulch thru the drip line

* apply winter protection if you want to produce blooms from those July flower buds.

An example of winter protection is to put chicken wire/burlap around 4-5 stakes that surround the hydrangea. The chicken wire should be taller and wider than the hydrangea stems. That helps protect the flower buds which develop usually near the end of the stems. When the plant begins to go dormant in the Fall, fill the area with dried out leaves, straw, etc. Pack the leaves really good, leave little empty space and save whatever is left in a plastic garbage bag so you can apply more in mid winter as the leaves settle. Make sure the side and top have around 3-6 inches between the ends of the stems to the chicken wire (the more distance, the more protection the leaves give). The top can be topped with cardboard; use rocks or bricks hold in place. Remove the winter protection about 2 weeks after your average date of last freeze.

Luis