I have 6 hibiscus plant that were planted about September, 2016; by a professional landscaper (??). Last year they grew and bloomed well. They were wateted about 3 times a week. This year they are about 4 feet tall, very dry and nothing but brittle sticks. There is no signs of growth, yet. Are they just a late bloomer? Should they be prunned back? Watered of fertilized now?? Should I lightly dig to check for life at the roots How can I save them?
These kinds of hibiscus are hardy, meaning their roots survive cold winter temperatures, but the top growth dies back to the ground each winter. You don't need to save them, this is normal.
The dead top growth needs to be pruned completely down each spring.
Here is more information about them: https://www.americanmeadows.com/hardy-hibiscus