Mushroom Growing Process


Mushroom growing process

HOW MUSHROOMS ARE GROWN

1/ STRAW WETDOWN & COMPOSTING

Good quality wheat straw is wet over several days & then a protein source is added plus gypsum.
Mushroom growing process

The gypsum helps to keep the compost open & the protein (often chicken litter) accelerates microbial activity. Temperatures up to 84?C cook & caramelise the straw making it suitable & selective for mushroom growth. The aim is to compost aerobically so most growers use under-floor ventilation & turn & mix the compost regularly over a 9 to 14 day composting phase. It is amazing to see how quickly the material can convert from dry wheat straw to a very dark homogenous compost if ideal conditions are created. Moisture should be 72%+, protein about 12.5% and microbial activity very strong still.
Mushroom growing process

2/ COMPOST PASTEURISATION & CONDITIONING

The material is now ready to pasteurise & condition in a specialised well insulated room with a powerful fan, filtration system & under floor ventilation. Air is recirculated through the compost which can be up to 2.5M high. This again is a totally natural process utilising micro-organisms to create the heat. There are five distinct phases.

EVENUP

A small amount of fresh air is used allowing the temperatures in the compost to even-up & the microorganisms to become active again. Normally this takes 12-16 hours to achieve 54?C+ with medium fresh air (indicating good strong activity).

PASTEURISATION

Once the compost is all heating above 57?C then minimal fresh air is set & 57-62?C should be recorded in the compost for 5-7 hours. Ammonia content in the compost & air will be very strong & this is very important to ensure a suitable kill of unwanted spores, fungi, Nematodes & other unwelcome guests.

DROP OFF

It normally takes about 6-8 hour to reduce the compost temperature to 53-54?C and maintain strong natural activity.

CONDITIONING

Over the next 4 or 5 days the temperatures are gradually reduced down to 45-46?C in the compost. For the first 2-3 days activity is strong while the micro-organisms lock up all unconverted protein & ammonia & then die off.

COOL-DOWN

The exhaust air will now smell free of any ammonia & it is time to cool down to 30?C for inoculation with mushroom spawn.

3/ SPAWNING

The compost is now mixed with spawn of the growers strain and often is supplemented with a matched slow release protein source. There are three distinct ways of spawn running/growing.

BULK SPAWN RUN

This is where the compost is put back into a room like the pasteurising room where recirculated air can be pushed through the compost to maintain ideal conditions for mycelial growth( 25-28?C & high CO2 levels).

SHELVES


Mushroom growing process

Spawned compost is filled onto long shelves 5 or 6 high in the final growing room.

LARGE GROWING BOXES

The compost is filled into large boxes(normally wood) and placed in a specialised spawn growing room for 14 days.

BAG GROWING

The compost is filled into plastic bags which are normally placed on some sort of shelf system in a growing room.

4/ CASING WITH A PEAT & LIME MIX

Once the spawn has fully colonised the compost then a 40-50mm layer of casing is added, normally containing casing inoculum(casing spawn). Some growers add supplement now instead of at spawning. The peat mix is added very wet & kept wet while the spawn colonises it(about a week).

FLUSHING

Once the peat mix is sufficiently grown with mycelium then some fresh air is introduced. By careful adjustment of CO2 (2500-1500ppm), humidity and air temperature, progressivelly small pinheads are encouraged to form & grow-out to button, cup & Flat mushrooms. Mushrooms grow in flushes about 7-10 days apart. The first is the most challenging to attain quality and yield. Generally 3 or 4 flushes are taken over 4-6 weeks of picking.

HARVESTING


Mushroom growing process

Growers that grow white mushrooms normally pick these as tight buttons & often can pick a crop several times in a day to attain the best quality. The brown mushroom is generally picked as a flat or portabello.

Mushroom growing process

As the crop is harvested the beds or cropping area is tidied of stalks & other mushroom trash & then the peat is wet again for the next flush. The size of mushroom farms in NZ vary between about 5 ton per week to over 100 ton.