Mushroom Growing Box: Climate Controller Build

Mushroom cultivation requires precise climate control — specific temperatures, high humidity, and fresh air exchange. A mushroom growing box with an Arduino-based climate controller automates these conditions, enabling consistent harvests of oyster, shiitake, and other gourmet mushrooms. This guide covers building a complete climate-controlled growing chamber for Indian conditions.

Why Climate Control Matters for Mushrooms

Mushrooms are not plants — they are fungi with very specific environmental needs:

• Temperature: Most gourmet species fruit between 15-25°C. Even small deviations affect yield and quality.
• Humidity: 85-95% RH is critical. Below 80%, mushroom pins dry out and abort. Above 95%, bacterial contamination increases.
• Fresh Air Exchange (FAE): Mushrooms produce CO2 and need oxygen. High CO2 causes long, thin stems and small caps.
• Light: Indirect light triggers pinning. Not as critical as temperature and humidity.

Temperature and Humidity Requirements

Common species for India:

Components for the Build

• DHT22 sensor for temperature and humidity (₹91)
• Arduino Uno or ESP32 (for WiFi monitoring)
• Relay module (2-channel) for humidifier and fan
• Ultrasonic mist maker/fogger for humidity (₹200-500)
• 12V fan for fresh air exchange
• Plastic storage box or modified refrigerator as the growing chamber
• LED strip for light (optional, 12-hour cycle)

Arduino Climate Controller

#include <DHT.h>

#define DHT_PIN 2
#define HUMID_RELAY 7  // Humidifier
#define FAN_RELAY 8    // Fresh air fan
#define HUMID_LOW 85.0
#define HUMID_HIGH 93.0
#define FAE_INTERVAL 1800000  // 30 min
#define FAE_DURATION 120000   // 2 min

DHT dht(DHT_PIN, DHT22);
unsigned long lastFAE = 0;

void setup() {
  dht.begin();
  pinMode(HUMID_RELAY, OUTPUT);
  pinMode(FAN_RELAY, OUTPUT);
}

void loop() {
  float hum = dht.readHumidity();
  float temp = dht.readTemperature();
  
  // Humidity control
  if (hum  HUMID_HIGH) digitalWrite(HUMID_RELAY, LOW);
  
  // FAE: run fan for 2min every 30min
  unsigned long now = millis();
  if (now - lastFAE > FAE_INTERVAL) {
    digitalWrite(FAN_RELAY, HIGH);
    if (now - lastFAE > FAE_INTERVAL + FAE_DURATION) {
      digitalWrite(FAN_RELAY, LOW);
      lastFAE = now;
    }
  }
  delay(5000);
}

Humidifier and Fan Automation

The ultrasonic fogger runs when humidity drops below 85% and stops when it reaches 93%. The circulation fan runs periodically (2 minutes every 30 minutes) to exchange air and distribute humidity evenly.

CO2 Management

High CO2 is the most common problem in sealed growing chambers. The periodic fan exchange (FAE) replaces CO2-rich air with fresh air. If mushrooms grow with long, thin stems and tiny caps, increase FAE frequency and duration.

Recommended Components

Growing Tips for Indian Climate

• Indian summer: Oyster mushrooms tolerate up to 28°C, making them ideal for Indian conditions without cooling. For lower-temperature species, use a Peltier cooler or place the chamber in an AC room.
• Indian monsoon: High ambient humidity helps — your humidifier runs less. But watch for contamination (trichoderma mould) which thrives in warm, humid conditions.
• Start with oyster mushrooms: Pink and grey oyster are native to India, tolerate higher temperatures, and are the most forgiving for beginners.