Urban Spore

How To Open A
Mushroom Grow Bag

Recently Opened Pink Oyster Grow Kit

What Are Mushroom Grow Bags?

Mushroom grow bags are strong, heat resistant bags which are used to sterilise supplemented substrates for mushroom growing and spawn production.

Mushroom grow bags feature a filter patch to allow for fresh air exchange which is essential for the healthy growth of mycelium while ensuring that the substrate remains free from contamination.

Pink Oyster Kit Side Fruiting

Opening A Grow Kit

There is no singular correct answer. Most mushroom hobbyists prefer to leave the bag in place while making a small incision through the plastic to expose a layer of substrate that has been well colonised by a thick layer of mycelium. This method ensures that the block is protected and maintains high levels of humidity. 

Mushrooms will grow in search of fresh air. Mushrooms will typically form where fresh air and high humidity converge on the surface of the substrate.

A few exceptions are species such as king oyster and lion’s mane which will often try to form fruits beneath the plastic where humidity is highest. This is due to these species having a lesser need for fresh air exchange. In this case the bag may need to be adjusted to allow for the fruiting bodies or mushrooms to develop.

Fully Colonised Pink Oyster Grow Kit

A Must Have For Every Mycophile

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When Is A Grow Kit Ready To Open?

Normally a grow kit will require 2 – 3 weeks from the date of production to fully colonise, this will be indicated by a layer of mycelium that will have grown across the surface of the substrate, similar to the layer of mould on an aged cheese. 

All of our mushroom grow kits are dispatched fully colonised and ready for fruiting. The mycelium will often appear less visible due to the agitation from being in transit. 

The grow kit can be opened to expose the substrate to fresh air. Mycelium will quickly begin to grow thicker and more visible where it receives most fresh air.

Species of oyster mushroom will often have thicker and more visible mycelium in comparison to lion’s mane which will produce a layer of fine translucent mycelium.

Most species can be refrigerated to prevent fruiting excluding summer species like pink & yellow oyster which may be harmed if stored at temperatures below 7 degrees Celsius.

Pink Oyster Grow Kit With Primordia

Different Ways To Open A Grow Kit

The mushroom grow kit needs to be opened to expose the substrate to fresh air.  The presence of fresh air will trigger the formation of primordia which grow into mushrooms. 

The method used to open a grow kit will depend on whether the species of mushroom being grown is side-fruiting or top-fruiting. 

Side-fruiting varieties include lion’s mane and most oyster mushrooms like pink, white, blue, yellow & brown oyster.

Top-fruiting varieties include king oyster, reishi, chestnut & pioppino.

Side-fruiting varieties can be opened by making a small 5 cm long cut into the grow bag to expose the substrate to fresh air. Tape can be used to hold the bag down firmly against the substrate to prevent the formation of primordia beneath the loosened layer of plastic.

Lion's Mane Grow Kit Recently Opened

Top-fruiting varieties like king oyster and reishi can be opened by opening the top of the bag and folding it over with a clip to restrict airflow. King oyster and reishi are often grown with restricted fresh air exchange to manipulate the growth style of the fruiting body.

King oyster mushrooms will produce larger, thicker stems with small, velvety caps when grown with restricted fresh air exchange.

Reishi will produce long antler-like formations until provided with adequate fresh air exchange provoking a change in growth to form large decorative conks.

Chestnut mushrooms can be fruited by removing the top of the bag as needed to reveal clusters of primordia that tend to form in the humid spaces between the substrate and bag.

Pink Oyster Grow Kit Recently Opened

Storing A Grow Kit In Fruiting Conditions

Once opened the mushroom grow kit must be stored in fruiting conditions for best results. Primordia will usually appear within 1 week when stored in optimum conditions.

Fruiting conditions revolve around humidity & fresh air exchange.

Humidity needs to be kept high to allow the mushrooms to grow large & healthy. Dry, cracked & leathery & discoloured mushrooms often indicate a need to increase humidity. Humidity can be increased via indirect misting or the use of a humidifier or simple fruiting chamber.

Fresh air exchange refers to the amount of fresh air moving around the grow kit. Mushrooms will exhale carbon dioxide which can accumulate within the fruiting. Mushrooms growing long, stretched and deformed often indicate a need to increase the amount of fresh air exchange

Please note that increasing fresh air exchange can often directly reduce humidity. Follow the link below to learn more about making a low cost fruiting chamber for maintaining optimum fruiting conditions.

Shotgun Fruiting Chamber

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