🍄Growing Mushrooms

This page is for educational purposes only and is not a recommendation to break your local laws in any capacity. The text here is copied from a Leafly article and lightly edited in some places for clarity.

Table of Contents

The core steps to a successful harvest include

  • Sterilisation: A food source (rice, grain, manure, sawdust, popcorn kernels, bird seed, etc.) is first hydrated, loaded into Mason jars or Unicorn Bags, and sterilized. Think of this as clearing a field before planting an orchard. Once competing organisms are gone, mushrooms can take hold easily.

  • Inoculation: The sterilized mushroom food is inoculated with spores or a living mushroom sample. These clones produce uniform mushrooms, or fruit, and multi-spore cultures can create countless variations.

  • Germination & colonisation: The inoculation is given time to mature and colonise the food source, becoming a white and fluffy mycelial network—like roots, but for mushrooms—and eventually, mushrooms.

  • Fruit block assembly: After colonisation, a grower breaks up the inoculated food and mixes it into a substrate, or growing medium—commonly coir, vermiculite, or sphagnum. The substrate provides the structure and water that mushrooms need to mature. Once thoroughly combined, the mixture is sealed inside a plastic bin.

  • Fruit block colonisation: Inside a sealed bin, mycelium spread into the substrate. The goal is to establish a fruit block, in which the mycelium joins the food and substrate.

  • Pinning: Once the block is fully colonised, primordia—aka “pins”—begin to form, indicating that it's time to introduce fruiting conditions. These pins will eventually swell and rise from the fruit block as mushrooms.

  • Fruiting: During fruiting, young mushrooms want high humidity levels and plenty of oxygen, circumstances referred to as “fruiting conditions.” As mushrooms grow, they consume oxygen and release carbon dioxide. Without the exchange of fresh air for CO2, mushrooms become susceptible to growth defects, dudding, and pathogens. If humidity levels drop too low, a substrate will eventually dry out and starve mushrooms of water.

Note on sterilisation

One of the biggest difficulties for new growers is contamination. Microorganisms like bacteria, yeast, and fungi can out-compete an inoculant and ruin a growing project.

Signs of contamination include:

  • Sour or weird odours

  • Presence of a yellow liquid used as a defence mechanism

  • Brown, sludgy deposits of rotting rice

  • Stalled colonisation or the formation of colour masses, most often green, red, pink, or competing shades of white

Contamination usually occurs from inadequate sterilisation techniques, dirty inoculants/spore solutions, unsanitary cultivation environments, or even a grower's body or clothing. Each time a project is handled or exposed to open air, a mushroom grower risks contamination.

In a home-grown environment that lacks laboratory-standard sterilisation and clean-room equipment, our best defence against contamination is to interact with a project as little as possible.

How long does it take?

The prep and inoculation phases can be knocked out in an afternoon. After
inoculation, colonisation can take anywhere from two to eight weeks, depending
on environmental conditions, genetics, and inoculation technique. Once the cups
are colonised and birthed, pins and fruits will form in about one to four

A full growth cycle of mushrooms can take anywhere from one to three months.


You'll need the following supplies for the inoculation phase:

  • Spore syringe or liquid culture

  • Minute Rice Brown Rice Cups

  • Micropore tape

  • x2+ 6-quart plastic totes, or similar plastic boxes

  • Nitrile gloves

  • Rubbing alcohol

  • Bleach

  • Spray bottles for alcohol and bleach

  • Fine-mist bottle for water

  • Lysol or other air disinfectant

  • N95 mask

  • Butane/propane torch, alcohol lamp, or similar

Supply list for the substrate phase:

  • Coir

  • Vermiculite (optional)

  • Gypsum (optional)

  • Distilled water

  • 5-gallon painter's bucket and lid

  • Nitrile gloves

  • N95 mask


This and the next step can be finished in an afternoon.

When picking a work area, avoid drafty rooms if at all possible. We want to get as close as we can to a sterile, laboratory-grade clean room. If there are vents, we're going to seal them up. Also avoid carpeted rooms because carpet traps contaminants.

After selecting a work area, sanitise it as deeply as possible. Ensure there's ample ventilation, then begin wiping every surface (walls, floors, doors) down with rubbing alcohol. Work top to bottom, and consider using bleach on surfaces that it wouldn't damage.

After sterilising every surface, gather the spore syringe, rice cups, torch, micropore tape, and nitrile gloves. Wipe everything down with rubbing alcohol and place on a sterile surface.

Begin sealing the room. Turn off any air conditioning systems, close or seal vents with plastic sheeting and tape, etc.

Spray the air with Lysol or a similar aerosol disinfectant designed to mitigate airborne contaminants.

Now clean your body. Take a shower, brush your teeth, and put on clean clothes. Right before heading back into your work area, wash your hands thoroughly with soap.

When ready to proceed, put on an N95 mask and enter the room.


Vigorously shake your spore syringe for a few minutes, making sure to break up any clumps of spores. Spores need to be evenly distributed through the solution.

Flame-sterilize the syringe needle with your torch or lighter. The needle should get red-hot.

Note: don't break the factory seal on the rice cup; that stays sealed until later.

When the needle has cooled, puncture the plastic covering on a rice cup in the middle and dispense between 0.5-1cc of spore solution. Don't use too much solution, as excessive moisture levels will encourage wet rot and bacterial infection.

Immediately cover the inoculation hole with a piece of micropore tape. Make 6 holes on one side, cover them with tape, 6 holes on the other side, then cover them with tape. The goal here is working as quickly and efficiently as possible to minimise the amount of time the contents of the cup are exposed to the air.

The spores now have a source of food and will germinate.

Repeat this process for each cup, sterilising the needle between inoculations.

To minimise the risk of contamination, try to avoid moving your hands around a lot and keep your work surface wet with rubbing alcohol throughout the process.


After inoculation, store the rice cups inside a 6-quart plastic box or similar plastic container and close the lid. Spores will begin to germinate, pair up, and exchange genetic information, maturing into a mycelial network.

To encourage a timely rate of colonisation, store the cups at around 65° F (~18.5° C). Warmer temperatures will encourage quicker colonisation, but anything past 70-75° F (21-23.5° C) can awaken dormant contaminants. Keeping the environment cool will elongate colonisation, but stave off competing microorganisms.

Once a week, gently agitate your rice cups in a back-and-forth or swirling motion, but don't shake the cup up and down. Doing so can expose grains of rice to the inoculation area, where contaminants are most likely to be hiding.

You can monitor the colonisation process by holding a cup up to a lamp; the dense mycelium restricts light from passing through, thereby appearing whiter than the uncolonised top portion of the rice.

Colonisation usually takes two to eight weeks. When the rice is fully colonised, it will solidify into a unified mass, eventually feeling heavy at the bottom of the cup. Colonisation can be confirmed by shaking the cup. Once few or no loose grains are felt rattling around, move on to the substrate assembly and birthing phases of mushroom growing.

Substrate assembly

When a rice cup is fully colonised, between a couple of weeks and a couple of months, you can move on to making a substrate (the growth medium) and birthing mushrooms.

Most people use a combo of coir, vermiculite, and gypsum (this combo is also called CVG). “Field capacity” refers to the ideal amount of water in a substrate. A substrate that's adequately hydrated to field capacity will establish Goldilocks-zone, aerobic soil conditions, and encourage healthy mushrooms. Field capacity is when just a few drops of water are produced when squeezing a handful of substrate. There's a good explainer video on YouTube; the instructions are reproduced here in case the video is ever taken down.

Make your substrate 8–24 hours ahead of time and use it within 24 hours; the longer the substrate sits around, the more likely it is to become contaminated.


  • 1 bucket, 6 gallons

  • 1 brick of coir, 650g

  • 8 cups vermiculite

  • 1 cup gypsum

  • 18 cups water


  • Put dry ingredients in bucket

  • Boil water

  • Pout water in bucket

  • Close lid, clamping down

  • Let sit at least 6-8 hrs to cool

  • Come back and mix everything up

  • Use within 24 hrs


Birthing only takes an hour or so, depending on how many rice cups you have. Before birthing, sterilise your work area again. Remember, your work area is like a surgical theatre and you’re the doctor. Cleanliness and hygiene are a home mycologist’s best allies.

When you’re all cleaned up and wearing a mask and gloves, it’s time to birth your cups.

First, sanitise a spoon with rubbing alcohol, then open a rice cup by breaking the seal and break up the consolidated rice. Add a small handful of substrate to the cup and mix it in with the inoculated rice.

Once the rice is evenly distributed throughout the substrate, gently compress the mix and add another layer of substrate. This layer will serve as a barrier between open-air contaminants and the rice mixture.

Now cups can be introduced to fruiting conditions.


Mushrooms need a humid environment and fresh air. To create such an environment, we use a well-sanitised 6-quart plastic box. After disinfecting the plastic box with rubbing alcohol, spray the inside with a fine-mist water bottle to increase humidity.

Put the cups inside the plastic box with the lid turned upside down—this leaves a small gap for air exchange, allowing fresh oxygen to displace the CO2 that mushrooms make while growing.

The easiest option for lighting is the diffused light from a window through the blinds. You can also use fluorescent lights and LEDs that mimic the spectrum of the sun. If you grow weed and have a T5 or T8 fluorescent tube hanging around, use that. The light simply needs to warm the box.

Keep the temperature the same as it was during the colonisation phase. Temperature regulation is critical because fluctuations create condensation and humidity.

You won’t need to water the cups directly, only mist the inside of the box before adding them. This jumpstarts the formation of fruits via evaporation and rehydration of the substrate during day and night cycles.

Once you introduce your cups to fruiting conditions, high humidity, ample fresh air, and a day-night light cycle, simply leave your project alone. Resist touching it. No daily misting, fanning, etc. is needed. Patience is key.

If the condensation on the inside of the bin evaporates entirely before fruits form, remove the cups and mist the walls and/or floor of the box again. Never mist the cups, fruits, or pins directly. Too much water will drown the mycelium and encourage pathogens to take root.

The plastic bin will first start to dry out where fresh air enters. If a dry zone doesn’t form after a few days, reposition the upturned lid to widen the gap to increase fresh air exchange.

Note: Some people close the lid and fan their fruiting chamber with the lid every so often. We don’t recommend this approach as it can mess with humidity levels. We suggest a passive fresh air exchange. As a rule of thumb, less interaction is more.

The fruiting phase can be broken down into three stages: pinning, elongation, and sporulation.


Mushrooms start as knots of hypha-like individual roots, but part of the mycelium: on the surface of a mycelial network. They grow where water droplets condense and evaporate.

Imperceptible to the untrained eye, these knots are the beginnings of primordia: better known as “pins” due to their pinhead-like appearance. Their formation is usually referred to as “pinning.”


As fruits mature, they will elongate and gain mass. This is when adequate fresh air exchange becomes critical. If fruit bodies bruise to blue, this indicates a CO2 build-up and growth will soon halt if the rate of fresh air exchange isn’t increased.

Fruits are ready to harvest when the caps open up, signalling that sporulation will soon begin.


At this point, the veil connecting the cap to the stem breaks and within a few days, spores will be visible on the substrate below. This is the mushroom’s way of repeating the lifecycle.

It’s common to harvest shortly before or after the veil breaks to avoid dark, inky spore deposits falling onto and colouring any underlying mushrooms.


When the veil connecting a mushroom’s cap to its stem breaks, it’s ready to harvest. To harvest, simply twist and pull each mushroom from the substrate. Alternatively, you can use a knife or scalpel to cut them free.

Once harvested, remove and discard any substrate that’s attached to the bottom of your mushrooms.

They should be eaten immediately after harvest or dried.

Air drying is sufficient, but they can also be put in a food dehydrator on a low-temp setting (120° F or less) for about a day. Mushrooms are composed of up to 90% water, so growers need to be thorough when drying them.

Once cracker-dry, mushrooms should be stored in a jar or similar container with a desiccant pack or two to maintain proper humidity levels. Ideally, store mushrooms in a dark space that stays at room temperature, not in a freezer or fridge.