Let’s take a closer look at these plants.
These plants are hardy up to zone 5b, but need protection from the cold and wind. Zone is the best place for them. This group includes the popular ‘Endless Summer’ long-blooming variety.
These are the least cold hardy hydrangea types, but you might be able to grow them where you have a suitable microclimate that offers protection from rapid freeze-thaw. A good spot might be a south facing wall. Don’t plant in a low area where cold air might collect.
H. mycrophylla are your blue and pink hydrangeas, depending on what type soil you have. An acidic soil yields blue flowers, and an alkaline soil makes pink blooms.