MushroomFarming / guide

Flush management

Interpret crop recovery, water demand, climate load and quality across successive flushes.

Practical explanation + detailed referenceSources & review ↓

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

Read this in the full guide: Run a Button mushroom crop from receipt to room reset →

Understand the topic

What you need to know.

A button crop does not come as a steady harvest. It comes in waves called flushes, with quiet days between them. This page is for growers who want to manage that wave: how the airing after case run shapes the first flush and the ones after it, how the air plan changes as flushes pass, what to do on the bed between two flushes, how long a crop runs, and which flush patterns are a warning rather than normal decline.

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

Part 01

A flush is a wave, and each wave is set up days before

After case run the room is cooled and fresh air is let in. The ICAR-DMR manual says this change brings pinheads in 3 to 4 days, and that the pinheads reach button size in another 3 to 4 days. In its climate section the same manual says pinheads form within a week. The ICAR-DMR Hindi folder for seasonal growers gives 2 to 4 days from pinhead to picking size.

A flush is all the mushrooms from one of these waves. Once they are picked the bed goes quiet while new pins form, and then the next wave comes.

So a flush is decided before you can see it. How many pins set, and how evenly, depends on the climate and the casing in the days before pinning, not on what happens on picking day. Treat each flush as a record of its own: the day picking started, the day it stopped and the weight it gave.

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

A dense flush of white button mushrooms fruiting from a compost bag with casing-soil specks, photographed in Assam, India. — A flush of button mushrooms standing in the casing soil of a compost bag. A flush is the set of mushrooms from one wave. Photo: Medhi jyoti, CC BY 4.0. Source

Part 02

Choose how hard to air the room, because it shapes every flush

The ICAR-DMR manual calls venting after case run a critical phase. It describes three ways to do it. The choice depends on whether you want one heavy first flush, or flushes of a size your market can take. The figures are the manual's targets for each style.

IfYou want smaller flushes that suit market demand (soft airing): ThenOpen the fresh air slowly. The manual's path: air to 19 °C in 48 hours and 17 °C in 72 hours, compost to 21 °C in 96 hours, carbon dioxide to 4000 ppm in 48 hours, 2000 ppm the next 24 hours and 1000 ppm after 72 hours, humidity from 98 to 92 percent in 48 hours.
IfYou want well-spaced flushes of moderate size (moderate airing): ThenRestrict venting a little. The manual's path: air to 17 °C in 24 hours, compost to 20 °C in 72 hours, carbon dioxide 2000 to 2500 ppm in 24 hours and under 1000 ppm in 48 hours, humidity from 98 to 92 percent in 24 hours.
IfYou want a heavy first flush and accept smaller flushes after it (severe airing): ThenPut no limit on airing. The manual's path: air to 15 °C as soon as possible, compost to 20 °C in 48 hours, carbon dioxide under 1000 ppm in 12 hours, humidity from 98 to 90 percent in 12 hours. Expect a heavy pin set.
IfPins come up in a mass, or form under the casing surface: ThenThe manual links this to a sudden fall in temperature, too much aeration, or carbon dioxide lowered earlier than recommended. Air more gently at the next venting.

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

Part 03

Fresh air is highest in the first two flushes, then eases

The crop breathes hardest early in cropping. The manual sizes the air to that, then reduces it once the first two flushes are picked. These are controlled-room figures; a seasonal room cannot set them exactly.

Air changes, from venting to the end of the second flushabout 6 per hourCarbon dioxide output is highest then, about 10 g per hour from each square metre of bed.

Air changes, later flushes4 per hourEnough to hold oxygen near 16 percent.

Fresh air vent, first two flushes30 % freshThe other 70 percent is recirculated.

Fresh air vent, later flushes20 % freshThe other 80 percent is recirculated.

Carbon dioxide once pins become buttons1000 to 1500 ppmFresh air can be slightly reduced to reach this.

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

Part 04

Reset the bed between two flushes

The gap between flushes is working time. What is left on the bed after picking decides how clean the next flush starts.

Pick the bed cleanRemove damaged pins and damaged mushrooms by hand, not only the saleable crop. The manual asks for this after harvest.
Keep cuttings off the bed and floorCollect stem cuttings as you trim. The manual warns that cuttings dropped on the floor or the bed promote unwanted microorganisms.
Fill the holesPut fresh casing where mushrooms were taken out.
Replace the waterPut back the water the flush took out, as set out on the watering page.
Hold the climate steadyThe manual keeps the cropping settings unchanged for the entire cropping period, and warns that high temperature held for long seals the casing and stops pinning.
Close the flush recordWrite the flush number, its dates and its total weight before the next wave starts.

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

Part 05

Flush patterns that need a closer look

After a heavy first flush the manual expects smaller flushes to follow. Some patterns are not normal decline. None of these signs names a cause on its own; each is a reason to check further.

Poor and delayed flushes, or high and poor yields taking turns in successive flushes. The manual lists both among the signs of nematode attack, with patchy mycelium and a sinking compost surface.
Late pinheads in the first flush, or pins forming below the casing surface. The manual gives these as an indication of dieback virus, with mushrooms in dense clusters that mature too early.
Bunches of mushrooms growing tight together. The manual points to the climate during pinhead formation and asks for it to be corrected.
Cut stems that turn purple or near black within hours, or overnight in cold storage. Mushrooms from the third flush to the end of the crop are the most susceptible, and watering before harvest seems to play a part.
Dry bubble spreading late in a long crop. The manual says it becomes more common when cropping runs beyond two months.

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

Part 06

How long to keep picking is a planning decision

The ICAR-DMR sources describe different crop lengths for different systems. There is no single number of flushes to aim for.

The Hindi folder for seasonal growers says the full crop is picked over 8 to 10 weeks, with mushrooms coming almost daily. The manual's farm design chapter plans controlled rooms on a 60 day cycle, which gives at least six crops per room in a year. Where 5 to 6 crops a year are taken, the manual notes that the cropping period is cut to about 4 weeks.

A longer crop is not free. Later flushes are smaller, and the manual notes that dry bubble becomes more common when cropping runs beyond two months. Compare each flush with the one before it, and decide when the room is worth more emptied and refilled. When the crop ends, it ends with a cook-out and removal of the spent compost, which the hygiene page covers.

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

Close each flush with a record

StartNote the day the first buttons of the flush are picked.
WeighWeigh every pick and total it for the flush.
GapNote the days with no picking before the next wave.
CompareSet this flush beside the one before and the same flush of the last crop.

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

Button Mushroom · cultivation stage

Flush management

Agaricus bisporus

Interpret crop recovery, water demand, climate load and quality across successive flushes.

Publication: Public editorial page
External review: Not yet recorded · needed from Button Mushroom technical reviewer
Updated: 2026-08-22
Evidence records: 2

Room climate by crop stage

Button mushroom, room air temperature. Case run spans 23 ± 1 °C (climate section) and 24 ± 1 °C (casing section). Source: ICAR-DMR manual 2011.

Temperature bandRelative humidity

Picture → explanation → field task

A crop-room round

AI-generated educational illustrations. Not actual farm photographs, diagnostic evidence or construction specifications.

Generated illustration of an operator inserting a temperature probe into a compost bed.

Measure the bed, not only the air

The probe measures growing material at a specific location. Room air and biologically active compost can have different temperatures. One reading is not a whole-room survey.

Try this on your farm

Use a consistent measurement location and method. Record time, crop stage and bed position with the value.

Generated illustration of gentle water application to a bare casing surface before mushrooms emerge.

Assess casing before watering

This scene shows casing without developing fruit bodies. Water needs depend on stage and material condition. The picture does not specify a quantity or a universal watering schedule.

Try this on your farm

Check the approved crop protocol and the actual casing condition before deciding how much to apply. Record the application.

Generated illustration of a grower recording different pin densities along mushroom beds.

Compare the pinning pattern

The bed does not develop uniformly at every position. Differences can involve inputs, water or room conditions. A patch is an observation, not a diagnosis.

Try this on your farm

Compare fixed locations over successive rounds. Photograph the same patch and record nearby readings before changing settings.

Generated illustration of an empty growing room with racks, dedicated cleaning tools and a hose.

Prepare for the next crop

The crop is removed before the room is prepared for reuse. An empty room provides access to surfaces hidden by a loaded crop. Clean appearance alone does not verify disinfection.

Try this on your farm

Follow the farm's validated cleaning and end-of-crop procedure, document completion and resolve defects before refilling.

Stage14

Crop-stage dashboard

Flush management

Biological state: The crop cycles through harvest and recovery
Operator objective: Support recovery without losing casing structure or crop quality
Handoff: Hand mature product to harvest and cooling

ObserveHarvest patterncasing recoveryquality

Depends onCrop historywater recordsroom recovery

Quick orientation

A flush is not only a harvest count. It is a changing pattern of development, crop load, water movement and room response that should be documented before the next intervention.

System role

Flush management connects one harvest wave to crop recovery and the remaining economic crop plan.

What to observe

Build a record before making a change.

Harvest pattern
Casing recovery
Crop quality
Disease and pest trend

Decision framework

Use the observation to narrow a decision, then verify the response.

Plan water around crop and casing state
Adjust labour and cooling readiness
Evaluate crop continuation
Preserve hygiene between picks

Dependencies and handoffs

This topic cannot be interpreted in isolation.

Cropping records
Casing water balance
Room recovery
Market specification
Farm crop plan

Practical layer

Start in the room with harvest pattern and casing recovery. Record location, stage and recent events before changing the process.

Technical layer

The technical model joins cropping records, casing water balance, room recovery. Any operating value must be attached to a registered parameter, measurement location and applicable condition.

Evidence boundary

This page is grounded in: Mushroom Cultivation, Marketing and Consumption; Mushroom cultivation frequently asked questions. Source provenance does not remove the need to check stage, system, date and local applicability.

Progressive depth

Go deeper without losing the field question.

PracticalWhat to notice in the room

Harvest pattern
Casing recovery
Crop quality
Disease and pest trend

TechnicalHow the interacting system is interpreted

Cropping records
Casing water balance
Room recovery
Market specification
Farm crop plan

ResearchWhich evidence records govern this page

ICAR-DMR-CULTIVATION-MANUAL
ICAR-DMR-FAQ

Technical registry

The numbers for this stage, with their source.

Values are published from ICAR-DMR guidance with the stage and measuring point they apply to. A parameter still marked pending has no published Indian value yet.

BUTTON.WATERING.APPLICATION

Water replaced after picking

1 L per kg picked

ICAR-DMR: replace about 1 litre of water per kilogram of mushrooms picked, applied as a fine spray and never so much that it pools on the casing.

Stage: Casing through cropping
Measured at: Calibrated application over the growing area
Crop meaning: Water put back onto the beds to replace what the harvested mushrooms carried away.
Applicable conditions: Stage; Casing material; Application method; Evaporation and drainage

published sourced

BUTTON.CLIMATE.COMPOST_TEMPERATURE

Compost temperature

20 to 25 °C

24 to 25 °C during spawn run, easing to about 20 °C once the room is aired for pinning.

Stage: Colonisation and cropping
Measured at: Within compost at defined bed positions
Crop meaning: Crop heat, which can sit above room-air readings.
Applicable conditions: Stage; Crop load; Probe placement

published sourced

Evidence and review record2 mapped sources

Sources support the page architecture and conceptual guidance. Technical values remain governed separately in the Button registry.

Tier A · foundational

Mushroom Cultivation, Marketing and Consumption

Broad cultivation, post-harvest and market context. Values are not promoted without page-level review.

Accessed: 2026-08-22
Publisher: ICAR-Directorate of Mushroom Research

Open original source

Tier A · institutional

Mushroom cultivation frequently asked questions

Institutional orientation for growers. It is not treated as a universal room recipe.

Accessed: 2026-08-22
Publisher: ICAR-Directorate of Mushroom Research

Open original source

Read the evidence

Sources & review.

Editorial update: 2026-08-22. Independent technical review is not recorded for this entry.

Mushroom Cultivation, Marketing and Consumption ↗
ICAR-Directorate of Mushroom Research
Mushroom cultivation frequently asked questions ↗
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 →