Upright and columnar trees solve the problem of wanting height where there is no room for width. Most stay under four metres wide at maturity while reaching ten metres or more in height.

Ornamental pears such as 'Cleveland Select' and 'Capital' are the most reliable performers, holding a tight pyramidal form without pruning. Skyrocket juniper, Pencil Pine and columnar magnolias give the same effect in evergreen.

Because the form is natural rather than clipped, these trees hold their shape with no ongoing trimming, which makes them considerably cheaper to maintain than a formal hedge doing the same job.