Cercis 'Forest Pansy' can reach heights of 10m, but if you prune it, it'll will be more shrubby and perfect for small gardens. Be prepared for an amazing colour change as the seasons progress – it's absolutely stunning.
Trees for small gardens: Olea europaea, the olive tree, grows slowly in our climate and this makes them perfect for containers. Pinch out the tips when the trees reach around 1.5m to keep them bushy. Photo by Paul Debois.