I have a summer cottage in Damariscotta (midcoast) on the river facing south, which I'm told this is more sheltered during the winter. I have lost 10 clethra planted in 2010, and I am looking for a plant that will survive. Before the clethra, hydrangea lived in the same location but did not bloom (too shady).

The site is along a fairly steep path that has very sharp drainage (I think this is the problem). The plants would ideally be maximum 30" tall and could sucker or spread horizontally. There's lots of shade from oaks and maples. The soil has been amended in the planting area. The cottage is rented out, so I need to depend on guests watering (not reliable) during the summer. I'm here this week and would like to get some replacement plants in so there can be some good root development before winter and before next summer's heat and possible lack of watering. Thinking about Itea or PJM Azaleas, or maybe Leucothoe fontanesiana (but they might need more moisture).

Any suggestions from veteran Maine gardeners will be greatly appreciated!