Columnar Trees & Shrubs: Our 8 Go-to for Narrow Spaces. Slender or narrow trees or shrubs are great assets to have in the landscape because they can be planted in restricted and tight spaces. Added bonus, their generally compact nature means that they very rarely, if ever, need to be pruned. Their strong, vertical lines make them ideal for breaking or lifting otherwise low plantings. Their best feature is providing a striking focal point in gardens!