The care of endless summer hydrangeas is covered in five categories: location, pruning, protection from freeze, fertilizer and watering. The endless summer hydrangea is known for longer blooming periods due to blooms on new growth as well as past years' growth.
Many gardeners who have tried growing this new breed of hydrangea have reported that the blooms don't last as long as they should, especially in the northern climates. Hydrangeas need around 6 hours of direct sunlight and partial shade. This type of hydrangea is not like the one in your grandmothers garden; it does not need to be hard pruned to the ground. The buds grow from old growth as well as new. If you take the old growth off, you only get one set of blooms. It's not hardy enough to last through a freeze. You may get lucky a couple times, but you should be sure to cover all buds through a spring freeze. The hydrangea only needs to be fed once with a slow release fertilizer, but forgetting this step can cause fewer and dull blossoms. Lastly, overwatering a hydrangea makes it grow, but only in the leaves and steams; the number of blooms decreases. The plant may wilt during the hottest part of the day, but watering well once a day makes for less guesswork.