Climate matters. This page is a practical baseline. Confirm cultivar, local frost/heat conditions, mature size and regional restrictions before planting.
Delphinium — Growing reference
| Scientific name | Delphinium elatum |
|---|---|
| Seed germination (days) | 14–21 |
| Soil temperature for germination (°C) | 15.6–21.1 |
| First harvest or flowering (days) | 365–730 |
| Measured from | Seed |
| Plant spacing (cm) | 45.7–61 |
| Mature height (cm) | 91.4–182.9 |
| Mature spread (cm) | 61–91.4 |
| USDA hardiness zones | 3–7 |
| Light | Full sun |
| Water | Moderate |
| Sowing method | indoor-start |
Growing directions
Use fresh seed — viability drops quickly in storage — and cold-stratify for 1–2 weeks before sowing at 60–70°F for best germination. Transplant after the last frost into rich, well-drained, slightly alkaline soil and stake early, as the tall spikes are highly susceptible to wind damage. Cut flower spikes back to basal foliage after the first bloom to encourage a second, smaller flush in late summer. All parts of the plant are toxic; all plant contact should be followed by hand washing.
Source and local conditions
Typical planning ranges from OpenPlantDB (CC0). Cultivar, climate, season and growing method can change these values. Confirm the seed label and local guidance before planting.
Source & verification
OpenPlantDB · CC0