My researches in trying to get the best harvest I could out of my mushroom growing efforts led me to the idea of a fruiting chamber. This is a structure that keeps the atmosphere surrounding the mushrooms high in humidity, while still allowing sufficient airflow so that carbon dioxide generated by the mushrooms can escape. Both low humidity and carbon dioxide build up and interfere with mushrooms fruiting.
People have made DIY fruiting chambers from many things, including: old modified fridges, shower screens or windows constructed to make a cabinet, or a plastic tub (or tote) with holes drilled in it. (called a ‘shotgun’ fruiting chamber). One of the more popular ones, and the design I chose, was to use a small plastic greenhouse, and by small I mean the 580mm wide x 380mm deep x 1280mm high model readily available in hardware stores, nurseries or online.
Initially I set it up inside the house, in our lounge room to keep it a bit warmer and relatively temperature stable. Also, seeing as it needed to be sprayed with water using a spray bottle regularly, I wanted it to be somewhere I could see it and go, “that’s right, I have to keep that thing damp!”
In its original form (just the greenhouse by itself) the fruiting chamber worked, but not very well and my sporadic spraying of water from the spray bottle didn’t help, it just didn’t keep the fruiting chamber humid enough, resulting in stunted mushies. There was also the other issue, on further research it seemed likely that due to the fact that the mushroom containers were fully enclosed to keep the humidity in, it also kept the CO2 in, which also results in stunted mushies!
I needed a two pronged approach to make my fruiting chamber work better. The continual (and ineffectual) spraying I was doing got old pretty quickly and so I needed to get something of a more automatic type that could keep the chamber humidity high, thus removing the need for continual intervention by me!
I got hold of a fogger/mist maker of the type used in small indoor water features, you know, the ones with a fountain that is shrouded in mist for a calming effect. You plug the fogger in and immerse it in a water supply, it uses ultrasonic waves to create a mist which then rolls out over the fountains landscape.
I bought one off Ebay for the vast sum of $20 including postage, I set it up on the top shelf of the chamber in a cat litter tray which I then fill with water to act as the reservoir. My idea was the water vapour would be generated and then flow down over the sides of the cat litter tray to the mushroom fruiting containers below, and that is in fact what happened.
To install it I punched a 12mm hole through the side of the greenhouse/fruiting chamber (see below) and then unplugged the fogger from the plug in transformer lead. I placed the fogger itself into the cat litter tray, ran the lead through the hole and reconnected it to the supply lead, then plugged in the transformer. I then used a bit of the micropore tape to seal the hole through which the supply lead ran. I turned it on, the result? Fog!
Next, to improve the ability of the system to remove CO2 without also removing the humidity, I hit on the idea of using a 12mm hole punch to make holes in the top and sides of the fruiting chamber and then covering the holes with micropore tape. The tape allows gas exchange while retaining the water mist inside and keeping any unwanted wild fungal spores outside. That was the theory I was operating under and it seems to have been successful.
Next, I needed a place to set up the fruiting chamber for full time use, and sitting it in the lounge room wasn’t going to cut it. All of that humidity is great for the mushrooms but there can be considerable condensation on the floor as a result. I have read that some people put theirs in the bathroom, for consistency of temperature (and the tiled floor would not be wrecked by the condensation) but our bathroom is too small for that so I elected to put it in the garage. The garage has a concrete floor but it does get a bit colder than I or the mushrooms would like but overall it seems to work very well except perhaps, in the depths of winter.
To use the chamber, just put your mushroom boxes, tubs, bags or whatever containing the spawn and substrate into the fruiting chamber shelves below the fogger and water reservoir, turn on the fogger and then zip up the front of the greenhouse/fruiting chamber and away you go. Keep a check on things every few days at least, so you can top up the water reservoir as required and see if fruiting has started. Some mushrooms will progress quite quickly so you need to keep an eye on them daily once they start to emerge and harvest them when they reach the stage you want.
So far I have found the fruiting chamber to work very well and, all things being equal, allow me to get a much better harvest from commercial kits and DIY mushroom growing set ups too. It was cheap to put together but it is remarkably effective, so if you want to grow your own mushrooms I would suggest putting one together.
