Mushroom Growing Light Cycle Calculator
Calculate optimal daily light and dark cycle for mushroom fruiting.
Covers oyster, shiitake, lion mane, and reishi with recommended hours and light intensity.
Light plays a surprising role in mushroom cultivation. While mushrooms do not photosynthesize like plants, many species use light as a directional cue (phototropism) and as a trigger to initiate fruiting body formation.
Light Requirements by Growth Stage
| Stage | Light Needed | Duration | Purpose |
|---|---|---|---|
| Inoculation | None (total dark) | 0 hours | Prevents contamination, no benefit from light |
| Colonization | None to minimal | 0–4 hours | Mycelium grows in dark; some species benefit from brief light exposure |
| Primordia formation | Moderate | 10–12 hours | Light triggers pinning in many species |
| Fruiting | Moderate | 10–12 hours | Directs growth upward, improves cap formation |
| Harvest | N/A | N/A | Harvest before spore drop |
Species-Specific Light Requirements
| Species | Colonization Light | Fruiting Light | Light Intensity | Spectrum |
|---|---|---|---|---|
| Oyster (Pleurotus) | 0 hrs | 10–12 hrs | 500–1,000 lux | 6,500K (daylight) |
| Shiitake (Lentinula) | 0 hrs | 10–12 hrs | 500–1,000 lux | 6,500K |
| Lion’s Mane (Hericium) | 0 hrs | 10–12 hrs | 200–500 lux | 5,000–6,500K |
| King Oyster (Pleurotus eryngii) | 0 hrs | 12 hrs | 500–1,000 lux | 6,500K |
| Maitake (Grifola) | 0 hrs | 10–12 hrs | 200–500 lux | 5,000–6,500K |
| Reishi (Ganoderma) | 0 hrs | 12 hrs | 500–1,000 lux | 6,500K |
| Button/Cremini (Agaricus) | 0 hrs | 0 hrs | None needed | N/A |
| Enoki (Flammulina) | 0 hrs | 4–8 hrs | 100–300 lux | Low intensity OK |
| Pioppino (Agrocybe) | 0 hrs | 10–12 hrs | 300–500 lux | 6,500K |
Worked Example — Blue Oyster Mushrooms in a Fruiting Chamber
Species: Blue Oyster (Pleurotus ostreatus var. columbinus). Stage: Fruiting. Light on: 12 hours. Light off: 12 hours. Intensity: 800 lux. Spectrum: 6,500K daylight LED.
Schedule: Lights on at 6:00 AM, lights off at 6:00 PM. Use a simple plug-in timer — no fancy controllers needed.
Sizing the light
Lux is just lumens per square meter of lit surface, so the arithmetic runs backwards from the area you are lighting:
Lumens onto the tray = Target lux × Area (m²)
Fixture watts = Lumens ÷ (LED efficacy × delivery fraction)
Efficacy for a decent 6,500K LED is around 100 lumens per watt. Delivery is the part people forget: a shop light hung 2–3 feet above a tub throws a good deal of its output at the walls and the floor, and in a small reflective chamber roughly half of it actually lands on the substrate. This calculator assumes 50%.
Run it for a 4 sq ft tub of oyster at the 750 lux midpoint: 4 sq ft is 0.37 m², so you need about 279 lumens on the substrate, which means a fixture putting out roughly 558 lumens, or 6 watts.
Six watts is a strange thing to shop for. Nobody sells a 6 W shop light, which is why the standard advice is to grab a 10 W LED bar and stop thinking about it. That is genuinely more light than oyster needs, and it does no harm. Mushrooms are not photosynthesizing; the light is a signal, not food, and overshooting the target costs pennies a month.
Daily Light Integral (DLI)
Some advanced growers track DLI instead of simple on/off hours:
DLI (mol/m²/day) = PPFD (µmol/m²/s) × Hours × 3600 ÷ 1,000,000
For mushrooms, DLI of 1–4 mol/m²/day is sufficient. This is far less than plants, which need 12–40+ DLI.
Electricity Cost Estimate
A 10W LED running 12 hours/day:
- Daily: 0.01 kW × 12 hrs = 0.12 kWh
- Monthly: 0.12 × 30 = 3.6 kWh
- At $0.12/kWh: $0.43/month — negligible cost.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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