Get a tree fern
We have three types in the garden, one of which is the popular Dicksonia antartica. The tall ones are Dicksonia squarrosa and they add height to the garden, as well as having more slender trunks. This tree fern can be kept outside in warmer parts of the country, but consider overwintering it under cover if temperatures regularly fall below -4°. D. squarrosa likes to be in filtered sunlight, loose well-drained soil with lots of organic matter and plenty of water.