Delphinium

The garden delphinium is the classic English cottage spire, sending up dramatic 1.5 to 2 m towers of densely packed flowers in true blue, violet, lavender, white, and pink in late June and July. Bred largely from Delphinium elatum and related alpine species, garden delphiniums are reliably hardy across Alberta (Zone 2 to 3) and one of the few perennials that genuinely thrive in our cool summer nights. Heavy nectar producers; hummingbirds and bumble bees both work them hard. The Pacific Giants strain (Round Table series, with cultivars like 'Galahad' white, 'Black Knight' deep purple, 'King Arthur' violet with white bee) is the prairie standard; 'Magic Fountains' and 'Aurora' series are shorter (1 m or less) and need no staking. All tall delphiniums must be staked before they bloom because Edmonton summer storms will flatten 2 m spikes within a single afternoon. Cut spent spikes back to a strong side bud immediately after bloom to get a smaller second flush in early September.