Delphinium Pacific Giant Summer Skies

Six-foot spikes packed with clear azure flowers, each with a small white eye at the centre that growers call the bee. It is the plant most people picture when they picture an English cottage border, and the Pacific Giant series was bred in 1930s California precisely to out-do the older European delphiniums for height and flower size.

Understand what you are taking on. From seed, year one is establishment and the flowering is modest; the real display arrives in year two and improves after that. At 1.8m it must be staked, and the stakes go in early in spring. By the time a spike is tall enough to look as though it needs support, the stem is too brittle to tie in without snapping it. Cut back hard after the June and July flush and you will often get a second, shorter flush in late summer. Slugs are the other enemy and they go for the new growth in spring, before there is anything to admire, so protect the crowns as they break.

Every part of a delphinium is toxic if eaten. Wear gloves to handle it and keep it well away from grazing animals.