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Everbearer Strawberry: GDD / GDH Behaviour (Practical Guide)

Everbearing strawberries do not behave like traditional June-bearing types. They have reduced dormancy dependence and a more temperature-driven flowering habit.

This page explains how to interpret GDD / GDH for everbearers safely and realistically.


Key physiological difference (important)

  • June-bearing strawberries:
  • Strongly chill-dependent
  • Flower initiation largely pre-determined
  • Everbearing / day-neutral strawberries:
  • Weak dormancy
  • Repeated flowering cycles
  • Development driven more by temperature and light than chill

As a result, thermal models must be interpreted differently.


Dormancy and chill in everbearers

Everbearers: - Still experience partial endodormancy - Usually require low to moderate chill - Exit dormancy earlier and more flexibly

Indicative chill ranges: - Utah Chill Units: ~150–300 CU - Dynamic Chill Portions: ~8–15 CP

These are guidance values, not strict thresholds.


GDD / GDH after dormancy release

Once dormancy is released, development becomes heat-responsive.

Typical patterns observed (after dormancy release):

Approx. thermal accumulation Development response
0–50 GDD (≈ 0–1,200 GDH) Leaf expansion resumes
50–120 GDD (≈ 1,200–2,900 GDH) First flowers visible
120–250 GDD (≈ 2,900–6,000 GDH) Fruit set and early harvest
Ongoing cycles Repeated flowering every ~80–150 GDD

Why GDH is useful for everbearers

GDH is especially valuable because: - Day/night patterns matter - Protected systems exaggerate temperature swings - Short warm spells can trigger flowering

GDH captures rate of change, not just seasonal progression.


Important limitations

  • Radiation strongly modifies response
  • VPD stress can delay flowering despite thermal accumulation
  • High night temperatures increase respiration and reduce yield quality

Thermal time explains when things happen — not how well they happen.


Practical takeaway

For everbearers: - Use chill to confirm dormancy release - Use GDD/GDH to anticipate cycles, not fixed dates - Expect variability between flushes

Everbearers reward observation as much as modelling.