Climate matters. This page is a practical baseline. Confirm cultivar, local frost/heat conditions, mature size and regional restrictions before planting.
Petunia — Growing reference
| Scientific name | Petunia × hybrida |
|---|---|
| Seed germination (days) | 10–14 |
| Soil temperature for germination (°C) | 21.1–23.9 |
| First harvest or flowering (days) | 60–90 |
| Measured from | Transplant |
| Plant spacing (cm) | 30.5–45.7 |
| Mature height (cm) | 15.2–45.7 |
| Mature spread (cm) | 30.5–91.4 |
| USDA hardiness zones | 3–11 |
| Light | Full sun |
| Water | Moderate |
| Sowing method | indoor-start |
Growing directions
Sow tiny seed on the surface of moist starting mix — do not cover, as petunias need light to germinate. Pinch transplants by one-third when planting to encourage branching. Deadhead or shear back leggy plants by half in midsummer to renew vigor and flush of bloom. Feed every two weeks with a balanced liquid fertilizer for best performance.
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