Climate matters. This page is a practical baseline. Confirm cultivar, local frost/heat conditions, mature size and regional restrictions before planting.
Comfrey — Growing reference
| Scientific name | Symphytum officinale |
|---|---|
| Seed germination (days) | 14–21 |
| Soil temperature for germination (°C) | 12.8–18.3 |
| First harvest or flowering (days) | 90–120 |
| Measured from | Transplant |
| Plant spacing (cm) | 61–91.4 |
| Mature height (cm) | 61–121.9 |
| Mature spread (cm) | 61–91.4 |
| USDA hardiness zones | 3–9 |
| Light | Partial sun |
| Water | Moderate |
| Sowing method | Division |
Growing directions
Propagate from 2–4 in root cuttings planted horizontally 2–3 in deep; plants grow vigorously and are nearly impossible to eradicate once established, so site them permanently. Mulch heavily around plants and cut back to the ground two or three times per growing season to harvest the biomass-rich leaves as a liquid fertilizer or compost activator. Leaves can also be processed into poultice form for topical soothing use on bruises and minor sprains. Note that internal use is not recommended due to pyrrolizidine alkaloid content.
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