Humidity is one of the most important factors involved in growing mushrooms. For many species high levels of humidity is required to trigger the formation of primordia.
Throughout development humidity is needed to ensure that mushrooms grow to maturity. A lack of humidity can cause them to stall, form cracks and discolour.
Mushrooms grown with adequate levels of humidity are often larger and will have a longer shelf life due to increase hydration.
How Much Humidity Is Needed?
The amount of humidity required will vary depending on the species of mushroom being cultivated. At a minimum mushrooms should be kept above 70%rH.
For some species too much humidity can result in areas of bacterial blotch. This can be identified as a slimy, discoloured area where moisture has accumulated. For this same reason it’s recommended to avoid directly misting fruits.
Misting With A spray Bottle
Spray bottles are a cheap and effective method to increase the humidity when growing smaller amounts of mushrooms. Spray bottles can generate droplets that stick to surfaces and increase humidity through evaporation.
The spray bottle should be used indirectly by spraying near or around the developing mushrooms or the interior walls of the fruiting chamber if applicable. Directly spraying the fruits too much may increase the chances of it forming contamination.
Is A Greenhouse Neccessary?
Greenhouses are ideal for mushroom growing however they aren’t necessary. Beginners will usually fruit grow kits or smaller projects without a fruiting chamber by storing the fruiting block out of direct winds and incorporate frequent misting to manage humidity.
A greenhouse can be used to create a stable environment in which you can better control humidity and fresh air exchange. It will produce more consistent results while reducing the amount of attention required.
A greenhouse with humidifier, humidity control & fan can be assembled for less than $150.
Making A Shotgun Fruiting Chamber
Alternatively, many cultivators will construct a fruiting chamber using a plastic crate or bag which has air holes for fresh air exchange which is crucial to the growth of healthy mushrooms. After spraying the interior sides of the crate the attached water droplets will slowly evaporate which will increase humidity.
A shotgun fruiting chamber is an excellent option for fruiting one or two kits at a time.