A landscaper suggested Hydrangea trees for the front of the house. The arched spot is 15′ wide and 8.5′ from the house to the tip of the arch. He suggested 5 otto lyuken laurels (3 behind and 2 in front) and 2 Hydrangea trees on each side of the laurels. I see some of these trees get large and I’m not sure that would work. What do you think?
It is not clear from your description how the arch will work be oriented, i.e. top of arch near house or near front yard.
The suggested otto lyuken laurels should be able to fit within the space, if you keep them pruned, as they typically have a spread of 6-8′ and can be kept smaller with regular pruning.
You have not indicated which species of hydrangea would be trained as tree for your arch. The height of hydrangeas varies, depending on the hydrangea chosen. It might be possible to train the hydrangeas so that their canopies open above the the otto lyuken laurels, in which case they could fit within the space, although it would be fully planted and would have to be kept pruned in order to confine the plants within the allotted space.
Feel free to send a picture of your space as we may be better able to assist you.