Contol-X Guide

CO₂, Humidity & Temperature Control in Mushroom Farms — The Complete Guide

By Poem Techno Private Limited  ·  Published May 2026  ·  8 min read

The three pillars of successful mushroom farming are CO₂, humidity and temperature. Get them right and yields are consistent, quality is high, and crops complete on schedule. Get them wrong and you lose entire batches. Manual management is error-prone and labour-intensive — automated climate control is now standard for profitable commercial mushroom farming in India.

CO₂ Control in Mushroom Farms

Carbon dioxide is produced by mushroom mycelium during respiration. In a closed grow room, CO₂ accumulates rapidly — especially at night when ventilation is reduced. High CO₂ is the #1 cause of poor-quality mushrooms.

CO₂ Effects on Mushroom Quality

CO₂ LevelEffect on Mushrooms
<800 ppmIdeal — thick caps, short stems, high market price
800–1500 ppmAcceptable — slight cap thinning
1500–3000 ppmLong stems, small caps — 30% price reduction
>3000 ppmCrop stress, pinning failure, potential crop loss

How Contol-X CO₂ Controller Works

The SCD30 CO₂ sensor reads ambient CO₂ every 5 seconds with ±30 ppm accuracy. When CO₂ exceeds the setpoint (e.g. 800 ppm for button mushrooms), the controller opens relay D1 (ventilation fan) for a configurable duration. The cycle repeats until CO₂ drops below setpoint. This maintains CO₂ within a ±50 ppm band around the target — impossible to achieve manually.

Humidity Control in Mushroom Grow Rooms

Mushrooms are 90% water by weight. They need ambient humidity above 85% to grow properly. A humidity drop below 75% for even 2–3 hours during fruiting can cause caps to crack, pins to abort, and weight loss of 15–25%.

Humidity Setpoints by Species

SpeciesSpawn RunPinningFruiting
Button85–90%90–95%88–92%
Oyster85–90%88–92%85–95%
Milky80–85%85–90%80–90%
Shiitake80–85%85–90%85–90%

Contol-X Humidity Control Logic

The SHT-series humidity sensor reads RH every 10 seconds. When RH drops below setpoint, Contol-X activates the humidifier relay. Misting duration is configurable (pulse width modulation) to avoid over-humidification. Upper RH limit (e.g. 96%) triggers ventilation to prevent condensation and contamination.

Temperature Control in Mushroom Grow Rooms

Temperature requirements vary significantly by species and stage. The most critical transition is pinning induction in button mushrooms — requiring a precise temperature drop from 24°C to 16°C over 12–18 hours. No manual system can reliably achieve this.

5-Sensor Temperature Monitoring in Contol-X

Contol-X reads 5 temperature points simultaneously:

  1. NTC1 — Air temperature, grow room centre
  2. NTC2 — Compost/substrate surface temperature
  3. NTC3 — Air temperature near HMI panel
  4. PT100 — Compost core temperature (high-accuracy)
  5. PT100-2 — Secondary position (door area, hot/cold spot)

Multiple temperature points reveal hot/cold spots, allow compost internal temperature monitoring (critical for Phase 2), and detect equipment failures early.

The SCD30 Sensor — Why It Matters

SCD30 CO₂ Sensor Specifications

Most cheap mushroom controllers use MH-Z19B sensors (±100 ppm accuracy). Contol-X uses SCD30 for 3× better accuracy — the difference between a ₹15/kg mushroom and a ₹22/kg mushroom.

Relay Control Logic — How Equipment Is Triggered

RelayEquipmentTrigger Condition
D0HeaterTemperature < lower setpoint AND door closed
D1Cooler / ACTemperature > upper setpoint
D2HumidifierRH < lower setpoint (pulse width control)
D3Ventilation fanCO₂ > setpoint OR RH > upper limit

Frequently Asked Questions

What is the ideal CO₂ level for mushroom grow rooms?+
Button mushrooms need CO₂ below 800–1000 ppm during fruiting. Oyster mushrooms tolerate up to 1200 ppm. Milky mushrooms tolerate up to 1500 ppm. Higher CO₂ causes long stems, small caps and reduced market value. Contol-X maintains CO₂ within ±50 ppm of the setpoint automatically.
How does an automatic humidity controller work in mushroom farms?+
A humidity sensor reads relative humidity (RH) every 10–30 seconds. When RH drops below the setpoint (e.g. 88%), the controller activates the humidifier relay for a programmed pulse. After the pulse, it reads RH again. This cycle maintains humidity within the target range — eliminating the manual misting schedule.
What temperature sensors are used in mushroom grow room controllers?+
High-quality mushroom controllers use multiple sensor types: NTC thermistors for air temperature (accuracy ±0.2°C), PT100 RTD sensors for compost core temperature (±0.1°C), and SHT-series sensors for combined temperature/humidity. Contol-X reads 5 temperature points simultaneously.
How many relay outputs does a mushroom controller need?+
A fully automated mushroom grow room needs at minimum 4 relay outputs: heater, cooler, humidifier and ventilation fan. Contol-X provides 4 relay outputs (D0–D3) plus door contact input, supporting complete single-room automation.
Can I set different CO₂ and humidity setpoints for each growth stage?+
Yes. Contol-X stage-based control allows you to define separate setpoints for spawn run, pinning and fruiting stages. The system transitions automatically based on elapsed time or manual stage advancement from the cloud CRM dashboard.

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