We have sandwiched a pool into a small yard with a northern and eastern brick wall, a patio, and our garage as the 4 sides. The walls are the backs of raised planters and only 6ft. from the pool. We need a tree or bush that can be trained as a tree that will cause root damage to the side of the pool. I prefer multi trunks. I can't find any plans at all for poolside gardens here. We are in Zone 8.