Hollyhock

Tall, upright and unmistakably old-fashioned, the Alcea rosea or Hollyhock sends a single flowering spire up to 2.5 metres from a low rosette of large, rounded leaves. The flowers open from the bottom of the spike upwards over several weeks, in single or double form and in almost every colour but true blue.
It is a short-lived plant, usually grown as a biennial, and it earns its place by giving instant vertical structure against walls, fences and the back of a deep border.
The Hollyhock delivers height and colour in a single season and remains one of the simplest ways to build vertical interest into a planted border.