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Mushroom Environmental Control

A governed climate guide to connect crop biology, heat, carbon dioxide, water vapour, air movement and control actions as one room system.

4 full chapters + technical referenceSources & review ↓
White button mushrooms on casing soil in long shelf beds inside a commercial cropping room near Eger, Hungary.
Real cultivation photograph. Read its source for location and context; it is not a universal operating specification.Andrew Bossi · CC BY-SA 2.5View full photograph ↗
On this pageChoose a section, or keep reading below
The full field guide

Read the room and make a controlled adjustment

Connect air temperature, substrate heat, humidity, carbon dioxide and air distribution to what the crop is doing.

Choose a picture to understand that part of the process.

  1. 01Air versus bed
  2. 02Three places for water
  3. 03Follow the air
  4. 04Prepare for failure

AI-generated teaching illustrations · Not photographs of actual farms

Chapter 01

Give every measurement a location and a purpose

Write the crop species, strain and stage before selecting a climate programme. Then distinguish room air, supply air, return air, compost or bag temperature, and product temperature. They are different measurement locations. A controller can hold its sensor at the selected value while the rear of the crop remains warmer or a nearby bed receives a drying draught.

Prepare a simple room map with marked front, middle and rear positions and representative upper and lower crop levels. Keep probes away from accidental direct spray and position them according to the instrument's instructions. Compare portable and fixed instruments using a suitable check method; two disagreeing sensors create uncertainty that should be resolved before making a large adjustment.

Collect a time history. A reading immediately after watering, a door opening or an equipment restart may represent a short event. Relate readings to those events and to crop response. Give the next shift a written record of changes so it does not reverse an adjustment before its effect has been assessed.

Different readings answer different questions
ReadingQuestion answeredCommon misinterpretation
Room air temperatureWhat surrounds the crop at this location?Assuming all substrate is at the same temperature
Substrate temperatureWhat is happening inside growing material?Treating one probe as the whole batch
Relative humidityHow close is this air to saturation at its temperature?Assuming wet air means correctly watered casing
CO₂ and air distributionIs gas removal reaching the occupied crop zones?Equating a spinning fan with adequate fresh air
Chapter 02

Separate humidity, watering and condensation

Water inside the substrate or casing is a crop resource. Humidity describes water vapour in the air. Surface wetness is liquid water on the mushroom or structure. These conditions interact but cannot be substituted for one another. Increasing humidification may not restore water to a dry casing layer, and adding water to a bed may leave unwanted wetness on caps.

Condensation occurs when a surface is cool enough for moisture in surrounding air to condense. Review product or surface temperature, air conditions and recent cooling or door-opening events when droplets appear. Air movement can help evaporation but can also dry exposed crop zones. The useful question is where moisture goes after an adjustment, not whether the room feels damp.

Observe the crop after watering under the selected crop protocol. Record water applied, time, affected zone and surface response. Keep observations comparable between flushes. An operator who can explain those changes has more useful control than one who only repeats a fixed number of watering cans each morning.

Chapter 03

Make an adjustment that can be evaluated

Begin with the observed problem and the most plausible explanation. Write the relevant reading, its location and the expected effect of the proposed adjustment. Change within the approved crop programme and equipment limits. Monitor the variables that the adjustment may also affect: fresh-air changes influence heat and moisture loads, and humidification can change both air and surface conditions.

Define when to inspect again using the response expected from the system and crop. A slow thermal response inside a bed should not prompt repeated large controller changes. If evidence becomes inconsistent, pause and verify the sensor or operating condition. Keep a record of the outcome even when the adjustment does not help; that result narrows the next investigation.

  1. 01

    Describe

    State the crop stage, affected zone and trend.

  2. 02

    Check

    Verify the measurement and recent operational events.

  3. 03

    Adjust

    Record the chosen change, its purpose and the responsible operator.

  4. 04

    Review

    Compare the expected and actual crop response before making another change.

Chapter 04

Prepare the response to equipment and power failure

List which loads are essential for the crop and which can wait during a power interruption. Have an engineer check the electrical supply, starting loads, protection and backup arrangement for the actual equipment. Room volume alone does not determine cooling capacity: outside conditions, building heat gain, fresh air, crop heat and operating schedule also matter.

Practise the reporting and recovery procedure with trained staff. Identify who receives an alarm, who checks the crop and who may work on equipment. After a failure, preserve the event history and inspect the affected crop locations. Restarting the machine does not prove the crop has already recovered.

Chapter sources & scope

These are educational explanations, not an independently reviewed operating protocol. Worked examples do not predict your yield or income.

Back to the chapter list ↑

Understand the topic

What you need to know.

This page covers what the crop needs from the air around it: temperature, humidity, carbon dioxide and air movement, and how each changes from spawn run to cropping. Button mushroom is the worked example because ICAR-DMR publishes the fullest figures for it. It also shows how to measure each one so that a reading means something. The rooms and machines that deliver these conditions are covered on the Production Room Engineering page.

Teaching revised 2026-09-24. Source-linked editorial synthesis; this date does not imply independent technical review.

Part 01

The crop makes heat, carbon dioxide and water vapour all day

A cropping room is not a store. The compost and the mushrooms are alive, and they change the air around them all the time. The ICAR-DMR manual measures this for button mushroom. In the first two flushes, each square metre of bed gives off about 10 grams of carbon dioxide an hour. At 17 °C and 88 percent humidity it also gives off about 10 watts of heat.

The manual manages four things for the crop: air temperature, relative humidity, carbon dioxide, and air speed over the beds. They are not separate dials. Warm the air and its relative humidity falls. Open fresh air to clear carbon dioxide, and the air handler has to cool or heat and humidify whatever comes in. The manual says temperature, humidity and carbon dioxide work together to start pinning, and pinning suffers if any one of them is out of range.

The crop also needs different air at different times. Spawn run, case run, pinning and cropping each have their own targets, set out in the next Part.

Source: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption

Real photograph of many Button Mushrooms growing across tiered wooden cultivation beds.
Button mushrooms cropping across tiered wooden beds. Every square metre of bed like this adds heat, carbon dioxide and water vapour that the room has to carry away. Photo: I. G. Safonov (IGSafonov), CC BY-SA 3.0. Source
Part 02

Button mushroom targets by stage, as ICAR-DMR publishes them

These are the manual's figures for a controlled room, and it marks several as strain dependent. Use them as the starting point you record against. Other ICAR-DMR documents give different fruiting temperatures: 14 to 16 °C in the manual's own species table and 14 to 18 °C in the seasonal folder. Growers without cooling follow the button folder, shown last.

Spawn run, 12 to 14 days23 ± 1 °C airBed 24 to 25 °C. Humidity 95 percent. Carbon dioxide 10,000 to 15,000 ppm, with all air recirculated and no fresh air.
Case run, about one week24 ± 1 °CHumidity 95 percent, carbon dioxide above 7500 ppm, no fresh air. The manual's climate section instead keeps spawn-run conditions here: 23 ± 1 °C air, 24 to 25 °C bed.
Pinning15 to 17 °C airReached within 2 to 3 days after case run. Humidity lowered from 95 to 85 percent; carbon dioxide 800 to 1000 ppm by opening fresh air.
Cropping1000 to 1500 ppm carbon dioxideFresh air slightly reduced once pins reach button size; temperature and humidity held as at pinning.
Seasonal rooms without cooling22 to 25, then 16 to 18 °CICAR-DMR button folder: 80 to 90 percent humidity in spawn run, about 85 percent after the room is cooled once case run is done.

Sources: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption · ICAR-DMR seasonal folder · ICAR-DMR button folder

Part 03

Temperature: the bed runs warmer than the air around it

Temperature has two places to watch: the air and the bed. The compost makes its own heat, so for spawn run the manual holds the air at 23 ± 1 °C and expects the bed at 24 to 25 °C. In a healthy crop the bed stays 1 to 2 °C warmer than the air. If the bed falls below the air temperature, the manual reads that as air too dry, pulling water out of the casing.

Some temperatures are limits rather than preferences. The manual and the NHB model DPR both say to avoid temperatures above 26 to 27 °C during spawn run and after casing, and to keep cropping below 18 °C, as part of controlling false truffle. The manual also warns that a long warm spell during cropping keeps the mycelium growing over the casing until it seals it, and pinheads stop forming.

When you write a set point, write next to it whether it is a limit like these or a preference. Only a preference can be traded against the cost of cooling.

Sources: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption · NHB DPR model, 2018

Reading the gap between bed and air

  1. Read the airRoom air temperature at crop height, beside the bed you will probe.
  2. Read the bedProbe the compost or casing of that same bed at the same time.
  3. Bed 1 to 2 °C warmerThe normal state the manual describes for a healthy crop.
  4. Bed colder than the airThe manual reads this as air too dry, drawing water from the casing.
Part 04

Humidity and water: three places, three different readings

Water sits in three places in a cropping room: in the casing and compost, as vapour in the air, and as liquid on caps and surfaces. Each affects the others, but one cannot stand in for another. These are the signs and limits ICAR-DMR and the NHB model DPR give.

  • Relative humidity compares the water the air holds with what it could hold at that temperature. Warm the same air and the reading falls, so always write the temperature beside it.
  • At cropping the manual holds 85 percent. That lets water leave the bed slowly, which draws nutrients upward and carries carbon dioxide and heat away.
  • Below 85 percent the bed loses more water, the casing dries and seals, and the crop suffers.
  • The bed drinks: about 31 grams of water leave each square metre an hour at 17 °C and 85 percent. After picking, the manual sprays 1 litre of water for every kilogram harvested.
  • Water left on caps invites bacterial blotch. The manual links it to a water film lasting more than 3 hours at 20 °C or above.
  • The NHB model DPR adds: avoid temperatures above 20 °C with humidity above 85 percent, ventilate after watering so caps dry quickly, and avoid temperature swings at high humidity that cause condensation.
  • Casing moisture is its own measurement. The manual keeps casing near 50 ± 2 percent at pinning; judge it in the casing, not from the humidity display.

Sources: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption · NHB DPR model, 2018

Part 05

Carbon dioxide: kept high to colonise, brought down to pin

Carbon dioxide is the factor the crop wants high first and low later. Through spawn run and case run the manual keeps the fresh air shut and recirculates all the air, because high carbon dioxide speeds the mycelium through the compost. Once case run is complete, the closed room becomes wrong. Pinning needs carbon dioxide brought down to about 800 to 1000 ppm, close to outside air, by opening fresh air.

The crop shows when this goes wrong. The manual says high carbon dioxide at pinning gives onion-shaped mushrooms with a bulbous base and a small cap, and during growth to button size it gives long stems with small, open caps. It traces both to gas trapped among the mushrooms, so its answer is better air movement over the beds, not only more fresh air.

Do not copy button figures to another species. For oyster, the manual asks for less than 600 ppm during cropping, while the ICAR-DMR oyster folder sets a limit of 800 ppm. Both are ICAR-DMR documents; follow one and record which.

Sources: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption · ICAR-DMR oyster folder

A dense bunch of long thin white enoki stems with tiny caps growing up out of a plastic bag.
Enoki, a different mushroom, grown in a bag for its long thin stems; the photographer notes that high carbon dioxide encourages them. Button mushrooms stretch the same way when carbon dioxide is trapped around the crop. Photo: Wendell Smith, CC BY 2.0. Source
Part 06

Air movement: enough fresh air, reaching every bed

Fresh air removes carbon dioxide and brings oxygen; circulation carries heat and gas off the beds. The manual gives both a volume and a speed. Volume alone is not enough, so check that air reaches the centre shelf of the middle row. The manual uses a burning incense stick to show which way the air moves there.

Air changes, venting to end of second flushabout 6 per hourThe period when carbon dioxide output is highest. The manual's casing section gives 4 to 6 at the first flush.
Air changes, later flushes4 per hourEnough to keep oxygen near 16 percent.
Fresh air share30, then 20 percent30 percent fresh and 70 percent recirculated in the first two flushes, then 20 and 80. None during spawn run.
Air speed over the bedsabout 15 cm per secondOver the crop beds, as the manual states it, not at the duct.

Source: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption

Controlled room: how the air moves

Cooled, humid air drops from the overhead duct onto the beds, returns through the room, and 20 to 30 percent fresh air is mixed in. About 15 cm per second over the beds, 4 to 6 air changes an hour. Source: ICAR-DMR manual.

Perforated supply ductAHUcooling coilhumidifierreturnfresh air 20-30%
Supply airReturn airBeds
Part 07

Measure where the crop is, and give every reading a place and time

A controller holds its own sensor at the set value. That says nothing about the far rack or the top shelf. These habits turn readings into evidence you can act on.

  1. Read air and bed togetherTake room air and bed temperature at the same place and time. The gap between them is itself a reading, as the temperature Part explains.
  2. Write humidity with its temperatureA humidity figure without the air temperature beside it cannot be compared later.
  3. Map the roomRead at the front, middle and rear, on upper and lower shelves, not only beside the door or the controller.
  4. Check the instrumentsCompare room instruments with one reference kept for the purpose. If two disagree by more than their stated accuracy, settle that before changing the room.
  5. Change one thing, then waitRecord what you changed and when, let the room respond, then read again. In the manual's soft airing, carbon dioxide falls from 4000 ppm at 48 hours to 1000 ppm after 72 hours.

Source: ICAR-Directorate of Mushroom Research: Mushroom Cultivation, Marketing and Consumption

Keep exploring

Every part of this topic.

Choose the stage, material or decision you need to understand next.

01

Environmental Control Fundamentals

A governed climate guide to separate biological requirements, measured room conditions, control actions and equipment duties.

02

Crop-Stage Climate Control

A governed climate guide to translate each crop stage into environmental objectives without flattening the crop cycle into one setpoint.

03

Room Air Temperature

A governed climate guide to interpret dry-bulb temperature through stage, location, time, humidity and crop response.

04

Compost Temperature

A governed climate guide to treat bed temperature as a biological signal and heat-removal obligation distinct from room-air temperature.

05

Humidity and Moist-Air State

A governed climate guide to distinguish relative humidity, humidity ratio, dew point and moisture load.

06

Carbon Dioxide in Production Rooms

A governed climate guide to balance crop generation, fresh air, return air, exhaust, leakage and sensor placement.

07

Oxygen and Crop Respiration

A governed climate guide to understand oxygen as part of gas exchange without using carbon dioxide as a perfect proxy.

08

Fresh-Air Control

A governed climate guide to admit enough conditioned outdoor air for the crop objective while accounting for its heat and moisture load.

09

Recirculation

A governed climate guide to use return air for mixing and conditioning while detecting short circuits and trapped zones.

10

Airflow and Distribution

A governed climate guide to separate fan volume, nominal air changes, velocity, direction and crop-level distribution.

11

Evaporation and Crop Water Demand

A governed climate guide to connect air state, air movement, surface condition, watering and crop development.

12

Vapour-Pressure Deficit

A governed climate guide to use VPD as a derived moisture-demand lens with an explicit surface or air reference.

13

Dew Point

A governed climate guide to compare air moisture state with surface temperature to anticipate condensation.

14

Condensation

A governed climate guide to trace condensation to dew point, thermal bridges, leakage, wetting and local air-state gradients.

15

Crop Respiration

A governed climate guide to connect biological activity to carbon dioxide, heat, oxygen use and water-vapour release.

16

Crop Heat and Room Heat Balance

A governed climate guide to turn stage- and load-dependent biological heat into a declared engineering load component.

17

Environmental Measurement

A governed climate guide to make sensor identity, placement, calibration, logging and uncertainty part of every reading.

18

Environment-First Diagnostics

A governed climate guide to start from a spatial and temporal observation, then test competing environment and equipment mechanisms.

Go deeper

Technical reference, records and tools.

Detailed crop-stage information, parameters, diagrams and specialist tools are kept together below. This material retains its source conditions and review limits.

Open the complete technical reference

Crop biology · room response · engineered control

The crop never experiences a setpoint in isolation.

A governed climate guide to connect crop biology, heat, carbon dioxide, water vapour, air movement and control actions as one room system.

System boundary
Crop to electrical supply
Numeric policy
Zero magic numbers
Calculation model
Inputs and assumptions visible
Verification
Empty and loaded commissioning

Choose an operating question

Read the crop, room and air as one changing system.

Environmental systems map

Follow the crop signal through the room, equipment, sensors and utilities.

1 of 6

Crop biology

Stage, crop load and respiration create changing heat, gas and moisture duties.

Trace both directions: crop demand to equipment duty, then equipment response back to crop.

Crop-stage climate sequence

These are the seven stages a button crop passes through, in order. Each one will carry its own reviewed set-points; those numbers are not published yet.

  1. Spawn run
  2. Case run
  3. Initiation transition
  4. Pinning
  5. Cropping
  6. Between flushes
  7. Termination

Why no numbers here yet. A set-point is only meaningful with the crop, the strain, the production system and a current source attached. Until those four are approved together, publishing a figure would invite growers to copy it into a room it does not describe.

Per-stage values will cover: Air temperature, Compost temperature, Relative humidity, CO₂, Airflow, Evaporation objective.

Reviewed environment parameters that are published today are listed in the parameter register, and the measurement method for each is set out in the sensor architecture library below.

Canonical route architecture

19 connected climate routes.

Educational digital-twin architecture

A future model can link room geometry, crop stage, sensor history, actuator states, load assumptions and maintenance events. It remains an educational architecture, not an autonomous controller or remote commissioning certificate.

Printable field sheets

Download a blank CSV, open it in a spreadsheet, and record the actual observations with units and references. These educational templates are not acceptance criteria or engineering certificates.

Evidence and review

Source type, applicability and limitations stay visible so older farm guidance is not mistaken for current engineering law.

foundational · biologyMushroom Cultivation, Marketing and Consumption

Indian Button Mushroom crop stages, environmental responses and cultivation vocabulary.

Published stage values remain source-specific and require strain, system and current-review context before approval.

Open primary source
current · biologyICAR-DMR Crop Advisory

Current India-season cultivation context and stage-specific environmental advisories.

An advisory is time, crop and context specific; it is not a universal equipment design basis.

Open primary source

Read the evidence

Sources & review.

Editorial update: 2026-08-23. Independent technical review is not recorded for this entry.

  1. Mushroom Cultivation, Marketing and Consumption ↗

    ICAR-Directorate of Mushroom Research

  2. ICAR-DMR Crop Advisory ↗

    ICAR-Directorate of Mushroom Research

Reading a source is not the same as applying its instructions to every farm. Confirm species, strain, crop stage, system, region and publication date. Old chemical recommendations are not current-use instructions.

See something that needs correcting? Tell us →

Quick answers · Follow the full explanation

Questions to resolve before your next step.

These short answers introduce the detailed guides. Keep each guide’s sources, conditions and review limits with its advice. Answer summaries updated 2026-10-01; this is not a new independent technical review.

What temperature and humidity are needed for mushroom farming?

There is no single temperature or humidity setting for every mushroom crop. Species, strain, stage, growing material and crop activity all matter. Select the crop-stage guidance first, distinguish room-air temperature from substrate temperature, and compare measurements at different rack positions before changing controls.

Compare species before choosing environmental settings →

Why can mushroom compost be warmer than room air?

The growing material and biological activity can generate heat, so room-air temperature does not necessarily describe conditions inside the compost. Read compost and air measurements together, note the crop stage and sensor position, and investigate distribution rather than assuming a single thermostat reading represents every bed.

Connect button crop stages with climate observations →

Does a humidifier replace ventilation in a mushroom room?

No. Humidification and fresh-air exchange serve different functions, and their effects interact with cooling, air movement and the crop. A humid room can still have poor air exchange or uneven conditions. Plan and commission these functions together instead of treating a humidity reading as proof that the room is ready.

Read the growing-room engineering guide →