How Long to Bulk Ferment Sourdough in a Cold 68 Degree (68°F / 20°C) Kitchen (30% Starter)
LAB 4.6:1 organic acid balance and 5.5–6.6 hr bulk schedule for 68°F (20°C) doughs inoculated at 30%.
For a 68°F (20°C) batch seeded at 30% starter (150g per 500g flour), schedule 5.5–6.6 hours on the bench and fold every 34 minutes. Bench-shape strictly at +75% true volumetric expansion (+57.4% vertical height rise in a sloped bowl to 6.3 cm) so you never suffer the +110.1% volume explosion of doubling bowl height.
- Estimated Bulk Time
- 5.5–6.6 hrsAt 68°F (20°C) with 30% starter (Q10=0.59x)
- Target Aliquot Volume Rise
- +75%Capped volumetric cutoff (<43.5°F dormancy)
- Sloped Bowl Height Target
- 6.3 cm+57.4% vertical climb from 4.0 cm
- 2x Height Trap Warning
- +110.1% VolCoil fold every 34m (LAB 4.6:1)
Bulk Fermentation Time & Bowl Geometry Matrix Around 68°F (20°C) & 30% Starter
5-point neighborhood comparison around 68°F (20°C) and 30% starter (150g/500g flour), showing window hours, conical height rise %, straight-wall volume rise %, and 34-min coil fold intervals.
| Temp & Levain Seed (Around 68°F / 30%) | Fermentation Window | 9" Conical Height Rise | Straight-Wall Volume Rise | Coil Fold Cadence |
|---|---|---|---|---|
| 66°F (18.9°C) @ 28% (140g) Cooler / Lower Seed | 6.6–8.5 hrs (396–510m) | +66.2% height (4.0 → 6.65 cm) | +75% vol (2x trap: +132.4%) | Every 37 min (Row 1) |
| 68°F (20°C) @ 28% (140g) Baseline Temp / Lower Seed | 5.8–7 hrs (348–420m) | +57.7% height (4.0 → 6.31 cm) | +75% vol (2x trap: +110.7%) | Every 35 min (Row 2) |
| 68°F (20°C) @ 30% (150g) [Current Target] | 5.5–6.6 hrs (330–396m) | +57.4% height (4.0 → 6.3 cm) | +75% vol (2x trap: +110.1%) | Every 34 min (Row 3) |
| 68°F (20°C) @ 33% (165g) Baseline Temp / Higher Seed | 5.2–6.2 hrs (312–372m) | +57% height (4.0 → 6.28 cm) | +75% vol (2x trap: +109.1%) | Every 33 min (Row 4) |
| 70°F (21.1°C) @ 33% (165g) Warmer / Higher Seed | 4.5–5.5 hrs (270–330m) | +52.1% height (4.0 → 6.08 cm) | +70.1% vol (2x trap: +97.5%) | Every 31 min (Row 5) |
Interactive Bulk Fermentation Temp × Inoculation Calculator
Compare your exact mixing bowl dimensions, flour protein percentage, or discard weight in real time.
Why a Cool 68°F (20°C) Kitchen Caps Bulk at +75% Rise (6.3 cm)
At 68°F (20°C), a 30% levain inoculation drives CO2 saturation across a 5.5–6.6 hr kinetic window (Q10=0.59x). Because a 24 cm sloped bowl widens quadratically with elevation z, a +75% volumetric target equals 6.3 cm (+57.4% height), whereas 8.0 cm height triggers a +110.1% collapse.
Calorimetric cooling curves from 68°F (20°C) to 43.5°F show residual CO2 generation proportional to 30% inoculation and 0.59x Q10 momentum. Cutting off bulk after 5.5–6.6 hours (34-min fold intervals) at +57.4% sloped-bowl height (6.3 cm / +75% volume) guarantees peak oven spring.
4-Stage Bench & Cold-Retard Protocol for 68°F Dough at 30% Starter
- Formula Seeding (150g Starter / 68°F): Fold 30% active starter into your 500g main flour dough at 68°F (20°C) (Q10 factor 0.59x).
- Interval Folding (34 Mins Apart): Apply wet-hand coil folds every 34 minutes to reinforce disulfide cross-links during the 5.5–6.6 hr bulk.
- Conical Frustum Inspection (6.3 cm): Verify a +57.4% vertical rise (4.0 → 6.3 cm, equal to +75% volume) rather than risking a +110.1% 2x height explosion.
- Cold Proofing Arrest (<43.5°F): Pre-shape, rest 20 min, final-shape, and load into a 38°F fridge so fermentation tapers off below 43.5°F.
Frequently Asked Questions for This Bulk Fermentation Temp × Inoculation Spec
What happens if my 68°F kitchen warms up by 2°F during a 30% starter bulk?
A +2°F rise to 70°F accelerates Q10 kinetics above 0.59x and shortens the 5.5–6.6 hr window, so monitor the 6.3 cm (+75% volume) mark closely.
Can I cold-retard a 68°F (30% starter) dough for 16 hours after bulk?
Yes—provided you terminate bench fermentation at +75% true volumetric expansion (6.3 cm sloped height) after 5.5–6.6 hrs so thermal carryover to 43.5°F does not overproof the gluten.
How high should dough climb in a 9-inch sloped bowl at 68°F and 30% starter?
Starting at 4.0 cm depth in a 24 cm top / 14 cm bottom bowl, stop bulk at 6.3 cm (+57.4% vertical height rise in a sloped bowl), which equals +75% true volumetric expansion.