Towering blue spires for the most dramatic arrangements
| Type | Perennial |
|---|---|
| Zones | 3–7 |
| Sun | Full sun |
| Height | 4–6 feet |
| Bloom Season | Early to midsummer |
| Vase Life | 5–8 days |
| Start | Start seeds 10–12 weeks before last frost, or buy plants |
Delphiniums produce the tallest, most intensely blue flower spikes available to the home grower. Their towering stature (up to 6 feet) makes them unmatched for creating dramatic vertical impact in large arrangements. They demand cool summers, making them a better fit for northern gardens.
'Pacific Giant' series is the classic tall cutting strain. 'Magic Fountains' is shorter (2–3 feet) and sturdier. For true blue, look for 'Blue Bird' or 'Summer Skies'. The annual form larkspur is much easier to grow and fills a similar role.
Delphiniums need rich, well-drained soil, consistent moisture, and cool temperatures. They struggle where summers are hot and humid. Start seeds 10–12 weeks before last frost (they germinate best at 60–65°F). Space 18 inches apart. Stake every plant—the tall stems are brittle. Feed heavily. After the first flush of blooms, cut spent spikes to the ground for a possible second bloom in fall.
Cut when the bottom third of the spike is open. Harvest carefully—stems are hollow and can snap. Condition in deep water. Vase life is 5–8 days.
Delphiniums provide unmatched height. They are the anchor of large-scale garden-style arrangements and wedding work. Pair with peonies, foxglove, and eucalyptus.
External: Delphinium Society