Mushroom Fruiting Environments

CREATING MUSHROOM FRUITING ENVIRONMENTS

Creating the right conditions for mushroom growth is a key part of growing mushrooms successfully. There are a wide range of spots where mushrooms can grow, ranging from a shady and sheltered spot in your back yard right through to a high-tech climate controlled grow room, and anything in between. If we imagine a sheltered, damp but fresh nook in the forest where we might expect to see a log covered in mushrooms, this is the climate we are aiming to create!

When creating a space to fruit our mushrooms, the three key aspects of conditions which mushrooms thrive in should always be kept in mind. Humidity, fresh air exchange and temperature.

1) HUMIDITY

Mushrooms, being a small, supple fruit body, require a humid environment to grow in. But not so much that they become soggy or over saturated. Humid air which feels like fresh moist air in a forest is what we are aiming for. Also keep in mind that wind and direct sunlight can be very drying, so shelter from wind helps mushrooms a lot too. Humidity gauges can be bought fairly cheaply but are often not super reliable - the best way to evaluate humidity is to look at the mushrooms. If they are cracked or yellowing at the edges, or shrivelling up before they reach full size, then its too dry. If they're glistening and soggy then its too humid. Avoid spraying water onto mushrooms directly - focus more on creating a generally humid environment around them. At a small scale (for grow kits) humidity can be provided with a spritzer bottle of water or a tray of damp perlite. Outdoors, just watering with the garden hose on mist or rain setting is all fine. For higher tech indoor grows, dedicated humidifiers (ultra-sonic mist makers) are often used.

2) FRESH AIR EXCHANGE

It's a common misconception that mushrooms are happy to be grown in an enclosed, musty, dark space. In reality, because mushrooms 'breathe' oxygen in and CO2 out (the same as us!), they need a good supply of fresh air to keep them happy. The telltale signs of mushrooms not having enough fresh air supply is weak, spindly growth with small caps and elongated stems. Fresh air can be provided in a number of ways - if the mushrooms are growing in a naturally airy space such as outdoors or in a partially enclosed shed, greenhouse or shade house, then its usually not a problem. For growing in more enclosed spaces, plenty of holes or mesh for ventilation are needed, or for grow tents or grow rooms (larger spaces with multiple fruiting blocks), actively exchanging the air with an exhaust fan is usually required. The exhausted air should be ducted outside due to the fact that its humid air and possibly laden with spores.

3) TEMPERATURE

Most of the mushrooms that we stock cultures of here at MycoLogic are either native to New Zealand or are naturally found here. We work hard to trial and select strains with a wide temperature range for fruiting. Most of our strains can be grown year-round in most parts of NZ without the need for heating or cooling. As a general rule of thumb, the warmer it is, the faster mushrooms grow (up to a point). Mushrooms can grow very slowly in the winter but the trade off for that is that they develop a wonderful texture and deeper more complex flavour when cold grown. Mushrooms grown in the height of summer can grow very quickly, but sometimes too quickly and have ruffled or thin edges or suffer heat stress. Generally speaking, most mushrooms fruit very well at temperatures between 10 and 28°C. Temperatures below zero or above 35°C will likely harm the mushrooms (although outdoor beds and mushroom logs can happily over winter through frosts etc and fruit again in the spring). The fruiting environments described on this page will work well for species like oyster mushrooms, pekepeke-kiore ('NZ Lions Mane'), shiitake, tawaka, enoki, hakeke / wood ear etc. If you have got yourself a ready-made mushroom grow kit you can fruit it in one of these setups.

OPTIONS FOR FRUITING ENVIRONMENTS

Making a specific 'mushroom fruiting chamber' is not always necessary. It may happen that you've got a spot around your property that will already work well for growing mushrooms, especially in the spring or autumn when temperatures are mild and humidity is generally high. Places like in a glasshouse under the shade of plants, under a deck, in a shed or garage or laundry room can be suitable environments if you mist around the mushrooms once or twice a day.

But if you don't have a good ready-made spot to put them, or the weather is dry, or theres lots of insects about, you may want to create a fruiting environment to grow your mushrooms in. We'll run through a few options here ranging from the small and simple through to larger and more complex.

MODIFIED CARDBOARD BOX

Sometimes the best solutions are also the simplest, and to be honest, its hard to beat the functional simplicity of a cardboard box with some holes cut in it, if you just want to fruit one or two mushroom grow kits at a time. I was surprised when I thought of this idea that I was unable to find any other examples of people doing it, because it works really well! This method is great because a cardboard box is free, it gets the job done, and when you're done you can simply put the box in the recycling, or even compost it!

To make a cardboard box mushroom fruiting chamber simply find a cardboard box of the appropriate size (taking into account the size of the block plus the amount of space the mushrooms will take up when they grow - plus a bit of extra space never hurts) and cut some holes in it using a craft knife. I usually cut triangles as its easiest to cut. Make several holes on each side of the box of about 3-4cm in width. Make sure to put at least one hole at the very bottom of each side of the box, due to the fact that CO2 is heavier than air and it will be able to easily 'drain' out of these lower holes.

From there, simply place your mushroom block into the box, and spray the inner walls of the box with plain water once per day. Avoid spraying the actual mushrooms themselves - by spraying the walls of the box, the water slowly evaporates and creates a nice humid environment for the mushrooms to grow in.

The photos here are of a single grow block box - however this method can be upscaled using bigger boxes to one that may hold 3 or 4 mushroom blocks at a time. You can also have the opening side on the side instead of at the top if you want.

'SHOTGUN' MUSHROOM FRUITING CHAMBER

These are similar in concept to the cardboard box, in the sense that the goal is to create an environment that holds humidity but also provides air exchange. These are just a little bit more durable, washable and longer lasting.

A 'shotgun' fruiting chamber is essentially a large storage tote bin with holes drilled in the sides - they get their name from the fact that they look like they may have been hit with a shotgun blast.

To make a shotgun mushroom fruiting chamber:

Find a storage tote with fitted lid of the size that you want. 60-100L is the common size range.
Use a quality, sharp drill bit of 7-10mm in size and a power drill to drill numerous holes around the tote bin (space the holes about 10cm or so apart). Hold onto the tote near where you are drilling the hole to prevent excess vibration, and drill gently and carefully as it can be easy to crack / split the totes (although its not a big problem if there is a couple of small cracks)
With a small, sharp kitchen knife make your way around the tote and trim off any excess plastic shavings from around the drilled holes by twirling the knife blade around the hole.
You're done!

Humidification for a shotgun fruiting chamber can be provided by simply spraying the walls of the chamber with water each day (avoiding spraying the mushrooms themselves) or, many people prefer to add additional humidification by way of some damp perlite. Perlite is puffed volcanic material which is light, inert (won't rot), and has a high surface area which makes it evaporate water quite effectively, creating humidity. Perlite is readily available at garden centres and is fairly cheap to buy.

Some people simply put a layer of perlite into the bottom of the fruiting chamber and wet it. Personally I find perlite to be a bit messy, and it does need changed from time to time if it grows algae etc, so I prefer to keep the perlite in a tray inside the fruiting chamber to keep it tidier. A baking rack can be placed over top of the tray for the fruiting blocks to sit on. From here, simply keep the perlite damp by adding water once a week or so, and it'll slowly release humidity into your fruiting chamber.

Another option is to have a fish tank bubbler with an aeration stone going into a large jar full of water inside the fruiting chamber. This humidifies the air as it comes in and as a bonus, also provides a small amount of active (rather than just passive) air exchange.

MINI MUSHROOM GROW TENTS

After much experimentation for an ideal easy and low tek growing environment for the hobby scale cultivator, we have found that our mini mushroom grow tents made of fine mesh are an ideal solution for fruiting a block or two of mushrooms at home. The mesh provides ample amounts of air exchange, holds humidity in the space, traps the bulk of spores which may potentially otherwise 'escape' into the room, and, most importantly, they create an impervious barrier to fungus gnats, which are one of the worst enemies of the mushroom cultivator!

A jar or tray of damp perlite can be kept in the tent to provide humidity (optional) as well as misting once or twice per day (maybe more in very dry weather). The mesh itself can be misted directly without even opening the tent, and water will evaporate from the mesh creating humidity. You can find mini mushroom grow tents in our shop in the 'Growing supplies' section.

MUSHROOM GREENHOUSE / 'MARTHA' TENT

For the home hobbyist who wants to have more than just one or two fruiting blocks going at a time, a mushroom greenhouse, also known as a 'martha tent' in some mushroom growing communities.

A mushroom greenhouse is a fairly simple structure with some add-ons to create good growing conditions for mushrooms. The base structure is usually either a mini greenhouse of whichever size you want (cheaply available from big-box garden centres) or a grow tent made from heavy fabric which are usually black on the outside and silver or white on the inside.

The two key additions to a mushroom greenhouse are humidification and ventilation.

Humidification is usually provided by way of an 'ultrasonic humidifier' which uses sonic vibrations to turn water into a fine mist. Units can be either free-standing with their own inbuilt water reservoir, or floating versions (often called pond foggers) can be placed inside a tub of water. Often times people will keep a big reservoir tub of water outside of the martha tent, and blow the humidified air in via ducting with a fan (note, the fan needs to be pushing dry air into the tub which then pushes the humidified air through the duct - don't suck up humidified air with a fan as it will ruin the fan).

Ventilation is usually provided by fans and ducting. One very important feature of a martha tent is to duct the exhaust air out a window or other vent hole to outside. When mature mushrooms are fruiting they release a lot of spores, and plus the air in the tent is very humid, so you don't want this air back in your living space.

Mushroom grow blocks are held on shelves / racking inside the tent. The tent will need to be cleaned from time to time as needed, to prevent buildup of spores and contaminants.

Mushroom greenhouses can range from the very basic to the highly 'kitted out'. Some people choose to add the likes of temperature, humidity and CO2 sensors (the 'InkBird' brand is a popular choice for these devices) and have various forms of automation. However, sensors can often be unreliable, and its entirely doable to simply tune the growing conditions 'by eye'... e.g. mushrooms lanky? Needs more air exchange... dry at the edges? Needs more humidity. Soaking wet or water logged? More air exchange and/or less humidity.