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Lesson 11 / 18 · Button Mushroom Grower

Cropping & Flushes

Button mushrooms come in waves called flushes, and the quiet days between waves are where growers lose money.

  • By the end you can describe a flush and the gap between two flushes.
  • By the end you can match fresh air to the flush you are in.
  • By the end you can build a crop calendar from your own diary.

Button mushroom crop cycle

A flush coming together on one bag, the wave pattern every button crop follows.

  1. CompostDay 0Pasteurised, ammonia below 10 ppm
  2. Spawn run12-15 days22-25 °C in the dark
  3. CasingDay 153-4 cm layer, pH 7-7.5
  4. Case run7-10 daysMycelium reaches the surface
  5. PinningDay 25Air the room, 15-18 °C
  6. FlushesDay 32-70Three flushes, 7-10 days apart

Read numerical examples with their source, method and crop context. They are not universal operating instructions. Historical prices are not current quotations.

Pinhead to picking size3-4daysthe Hindi folder says 2 to 4 daysSource: ICAR-DMR manual, 2011
Picking period, seasonal8-10weeksafter casing, seasonal cultivationSource: ICAR-DMR button folder
Air changes, first two flushes6per hour4 per hour from the third flushSource: ICAR-DMR manual, 2011
Carbon dioxide during cropping1000-1500ppmafter pinheads become buttonsSource: ICAR-DMR manual, 2011
Yield, long method compost10-15kg per 100 kg compostshort method 18 to 25, indoor 20 to 30Source: ICAR-DMR manual, 2011
Crops per room per year6cropscontrolled unit on a 60 day cycleSource: ICAR-DMR manual, 2011
Illustrated Button mushroom pins at different sizes on a casing surface.
AI-generated teaching illustration · not field evidence
Connect the picture to the lesson

Recognise developing pins

Notice
Tiny pins develop at the casing surface before visible mushrooms enlarge.
Understand
The condition of the crop matters alongside the planned transition date.
Try it
Compare marked bed locations and record where development differs.
See where this fits in the full workflow →

01Waves, not a steady harvest

After venting, pinheads appear in 3 to 4 days and reach picking size in another 3 to 4 days. The bed then goes quiet while the mycelium rebuilds, and a second wave follows.

DMR's Hindi farmer folder gives 8 to 10 weeks of picking in seasonal cultivation. Environment controlled units plan a 60 day room cycle and 6 crops per room per year.

DMR does not publish a line saying first flush on day N with so many flushes in total, because compost, strain and room all move it. Your own diary is the calendar.

02Fresh air changes with the flush

Carbon dioxide production peaks in the first two flushes, when DMR measures about 10 g of carbon dioxide per square metre of bed per hour.

For that period DMR asks for about 6 air changes per hour, with the fresh air vent at 30 per cent and 70 per cent recirculated. From the third flush, 4 air changes per hour hold oxygen near 16 per cent and fresh air drops to 20 per cent. Room carbon dioxide during cropping sits at 1000 to 1500 ppm.

Running full fresh air all crop long only burns power and dries the casing.

03What you do between flushes

Pick the bed truly clean. Every stump, broken stalk and dead pin left behind is food for moulds and a breeding site for flies.

Put back the water the crop took away. DMR's rule is one litre of water for every kilogram of mushroom harvested, applied after picking rather than onto swelling pins.

Hold the band steady. Warming the room does not restart a crop, it only invites disease. Expect each flush to be smaller than the one before and plan labour that way, so your pickers are not idle in week six.

04Yield follows the compost

DMR's Table 7.1 gives yields per 100 kg of compost by method: long method 10 to 15 kg, short method 18 to 25 kg, indoor method 20 to 30 kg. Some seasonal growers taking a single crop have reported 18 to 22 kg with long method compost.

NHB's strain table runs from 14 to 16 kg for older strains to 22 to 27 kg for DMR-NBS-5 under Indian conditions. DMR's own project model assumes 18 kg per 100 kg compost.

These are reported ranges, not promises. Weigh your compost and weigh your crop.

Draw your own flush calendar

  1. Write the venting date as day zero in the farm diary.
  2. Record the weight picked from each room every picking day.
  3. Mark the days with no picking; those gaps are your flush intervals.
  4. Divide total weight by compost weight to get kg per 100 kg.
  5. Compare that with the DMR range for your compost method.

Write in your farm diary: Daily picked weight by room, flush number, days with no picking, compost weight.

Mistakes that cost a crop

  • Leaving stumps and dead pins on the bed, which feed moulds and flies.
  • Holding maximum fresh air all crop, which dries the casing and burns power.
  • Copying another farm's flush calendar instead of recording your own.

Check yourself

Three questions, instant answers

  1. DMR asks for how many air changes per hour up to the end of the second flush?

  2. You picked 40 kg from a room today. How much water does DMR's rule ask you to put back?

  3. Long method compost yields, as published by DMR, are:

An editorial self-check, not a certificate. Answers are not stored, not even on this device.

Words used in this lesson

Flush
One wave of mushrooms, picked over a few days, followed by a quiet gap.
Air change per hour
How many times the whole room volume of air is replaced in an hour.
Recirculation
Air sent back through the cooling unit instead of thrown out.
References & further reading
Button mushroom cultivation and climate knowledge

Operating values require stage, strain, sensor and production-system context.

Open current reference
The guide behind this lessonOpen the reference guide