thermal → gdh_bbch_bands
This page provides indicative relationships between accumulated thermal time (GDH or GDD) and phenological development (BBCH stages).
These values are not fixed thresholds and must be interpreted with care.
This information is intended for pattern recognition, not prediction.
Most published phenology and BBCH reference data is expressed in Growing Degree Days (GDD), not Growing Degree Hours (GDH).
Agrinomy uses GDH internally for higher-resolution modelling, but BBCH stage relationships are best interpreted using GDD-scale magnitudes.
As a guide: - 1 GDD ≈ 24 GDH - Values shown below are given in GDD-equivalent ranges - GDH values will therefore appear much larger numerically
After confirmed dormancy release
| Approx. thermal range (GDD) | Typical BBCH stage |
|---|---|
| 0 – 50 GDD | Bud swell (01–03) |
| 50 – 100 GDD | Green tip (07–09) |
| 100 – 180 GDD | Tight cluster (51–53) |
| 180 – 300 GDD | Flowering (60–65) |
| 300 – 500 GDD | Fruit set (69–71) |
| 500+ GDD | Early fruit development (72+) |
After dormancy release
| Approx. GDD range | Typical stage |
|---|---|
| 0 – 80 GDD | Leaf expansion |
| 80 – 150 GDD | Flowering |
| 150 – 300 GDD | Fruit set and fill |
| 300+ GDD | Harvest flush |
(For GDH users: multiply GDD values by ~24 for approximate GDH equivalents.)
Biology is probabilistic.
Using bands: - reflects real crop behaviour - avoids false confidence - supports decision-making without over-promising
Thermal time describes tendencies, not guarantees.