Loading... Please wait...

Detailed Reishi GIY Kit Instructions


What’s in the kit:

The kit contains a bag of mineral-supplemented sawdust pellets and a full-sized growing bag containing live mushroom spawn (mycelium). Besides these instructions, that's all you need. You add the ingredients to the spawn in the growing bag.

What else you will need:

  • Five cups of drinkable water (see later section for more info)
  • Adhesive tape for sealing the growing bag. Ordinary packing tape works fine
  • 5 ounces of 3% hydrogen peroxide solution (from a pharmacy or grocery store)
  • Alcohol for sanitizing surfaces, like rubbing alcohol. You can use a disinfectant cleaner if you prefer. You may also want to use hand sanitizer rather than alcohol for your hands.
  • Scissors and/or knife

Get ready:

  1. Choose a clean, quiet place to work. Turn off fans, close windows, and keep others (like pets) from moving around in your work area to minimize the dust in the air. Clean your work surface and wipe with alcohol.
  2. Wash your hands thoroughly with soap and water and wipe them with an alcohol-soaked paper towel or hand sanitizer to reduce contaminants. 


You're ready to get started! Just follow the step-by-step instructions in the next section.

You can watch video demos online at demo.TheImaginaryFarmer.com Some of the kit details have changed, but the videos will still give you a good sense of what’s involved, and they’re fun to watch!


  1. Squeeze the unopened spawn bag to break the spawn into small pieces.
  2. Cut the spawn bag open across the top, just below the seal.
  3. Add 4 cups of water, and the coffee grounds, to the bag.
  4. Roll down the top of the bag a couple of inches, hold it closed, and shake vigorously until thoroughly mixed. Take care not to damage the filter patch.
  5. Empty the pellet mix into the bag, close it and again shake vigorously, until the spawn bits spread all through the mixture.
  6. In a separate cup or bowl combine the 5 oz. peroxide with one cup of water. Pour the peroxide solution over the top of the substrate mixture in the bag.
  7. Shake the bag gently to mix the solution around.
  8. Fold the top inch of the bag over and tape it securely, sealing it as well as possible to prevent dust or insects from getting in. Don’t tape over the filter patch! Make sure you leave air space in the top of the bag for circulation.
  9. Let it sit for an hour or so to let the pellets fully expand.
  10. Massage it gently to shape the substrate into a loaf. Squeeze it upward a bit so it does not press too tightly against the lower part of the bag.

Your mycelium will begin colonizing the substrate right away. You should see growth within a day or so!

The Spawn Run:

Let the bag incubate somewhere in your home where you can keep an eye on it easily, because you will want to observe the mycelium spreading through the substrate. Mushroom growers call this the spawn run. It needs moderate temperatures. 60°F is ideal, but it can thrive during this phase at any temperature up to 80°F. It should have little or no light. Too much light may cause premature primordium formation.

After about two weeks, examine the bag daily. You will see the mycelium change from cottony fibers to a more solid mass. When the mass begins creeping up the sides of the bags an inch or so, or lumps begin rising on top of the substrate, it is ready to fruit. If you want to grow strange, unpredictable shapes, leave the bag intact and fruiting bodies will grow upward toward the filter patch. When you have structures you like, which could take a month or two, proceed with the Fruiting instructions.


If you let it grow upright structures in the bag, gradually, over several days, cut the top of the bag off, an inch or two at a time, until about the height of the tallest fruiting body. If growing in shelf form, tape down the top of the bag to close off the filter patch, and cut a 2" horizontal slit horizontal in the end of the bag (the narrow side). As soon as you have cut the bag open, mist the exposed surface several times a day.

Shade all but the open end of the bag. For example, cover it with a or bag, box, or cloth to block light. Make sure the open end gets light and fresh air.

If you have dry air -a common problem during the winter - consider making a humidity tent out of clear plastic or other clear material to cover the kit with between mistings. If you do, make sure not to seal off the kit entirely; it needs ventilation, especially near the bottom of the tent (where carbon dioxide can collect).

Continue to mist or sprinkle the exposed substrate with fresh water at least once a day. If outside in warm weather, wet it thoroughly during dry weather, using a hose or watering can. The fruiting process proceeds for weeks, or longer, depending on the temperature. The fruiting bodies will darken and harden as they mature, but the growing, leading edge will remain white and tender. As it matures the block will turn varying shades of yellow and brown, depending on how much light it gets. It may look unhealthy but it's normal.


When the white growing edge begins to darken, or brown spore dust forms on top of the mushrooms, it's time to harvest. Cut or break them off the block. Dry them whole for decorative use, or cut or break them up and dry them to use in medicinal teas. Drying them upside-down in sunlight increases their vitamin D content dramatically!

Additional Crops

A healthy block will usually produce a second time, especially if you keep it in the shade outdoors in warm weather and occasionally soak it (or let it catch rain). Slit the side of the bag to let excess water drain out. If you have strong shade you can remove the bag entirely to let the block enjoy the air and rain, and reach into the soil for additional nourishment.

Frequently Asked Questions

Does this kit grow mushrooms or fungus?

A mushroom is the reproductive organ, or fruiting body, of a fungus. The kit produces fungal fruiting bodies

What species of mushroom is this?

The mushroom's scientific name is Ganoderma Lucidum. It has been used as a medicinal mushroom in East Asia for more than 2000 years. It is called Reishi (Japanese) or Lingzhi (Chinese).

What does the substrate mixture contain?

The reishi mushroom fungus digests wood, usually of dead or dying trees. We have you prepare a sawdust-based mixture for the mushroom to grow in. Specifically it contains about 34 ounces/970 grams of mostly hardwood sawdust pellets, a teaspoon each of limestone (calcium carbonate) and gypsum (calcium sulfate). You add the rest of the ingredients, as described at the beginning of the instructions.

How does the plastic growing bag work?

The bag is designed specifically for growing fungus. It has a filter patch that keeps contaminant particles out but lets gases pass through, so the fungus inside can breathe. These polypropylene bags can withstand the heat of steam sterilization, a feature which you don't need to take advantage of. They are reusable, but unfortunately not recyclable.

Can I use a thermal food storage sealer instead of tape to seal the growing bag?

Yes, you can seal the growing bag with a heat sealer.

How do I know my spawn is alive and healthy?

First, the spawn bag should be intact, without holes or tears. If it is rolled up, unroll it and look through the plastic bag at the contents. The grains should look clean, with only white mycelial fibers growing on it, and possibly with a few droplets of clear yellow fluid. Patches of green or other colors indicate contamination.

If the spawn has no visible signs of contamination, break it loose into individual grains by squeezing and shaking the bag, then let it sit at room temperature, out of bright light, for a couple of days. If healthy the mycelium will regrow and begin to bind the mass of grains together as a unit. If it does not stick together after a few days, or discolors, you have a problem.

How long will my kit keep before I have to use it?

We try to deliver spawn at its peak of readiness for introduction to its new substrate. It should retain its vigor for a week or two at room temperature. The longer you wait to use it, the greater the chance it will perform poorly.

What do the instructions mean by “drinkable” water?

Water chemisty varies from place to place. Our kit formula works best if you initially mix it using water with a neutral or somewhat alkaline pH (7 or higher) and without strong chlorination. If you have acidic water (pH under 6), or if you just don't know about your water's chemistry, we suggest using distilled or bottled drinking water instead of tap water when you mix your substrate. If you have chlorinated tap water, let it sit for a day to lose its chlorine, or use distilled or bottled drinking water. Do not use “softened” water, which contains a lot of salt.

For misting, drinkable tap water, including chlorinated water, works fine.

Why do you emphasize cleanliness when mixing the substrate?

We create a rich substrate that can potentially support many kinds of fungus, for example, molds, which will compete with the fungus we want to grow, possibly even killing it. We try to minimize the number of uninvited spores and live micro-organisms that get into the container. A little bit won't hurt – the peroxide will take care of it.

What does the peroxide do?

Using hydrogen peroxide in the right concentration keeps spores from germinating, providing a defense against contamination, while allowing the live mycelium to grow.

Why doesn't peroxide harm the mushroom's mycelium?

Wood-consuming fungi can cope with a certain amount of peroxide in their substrate if they have gotten used to it. The spawn we include in the kit was raised using peroxide so it doesn't mind the peroxide in its new substrate. We call it peroxide-conditioned spawn. If you used spawn that had not had peroxide-conditioning, the peroxide in the mixture would kill some of possibly all of it.

How do I know the mycelium block is ready to fruit?

For the first two or three weeks the mycelium looks like cotton fibers spreading through the substrate. Then it will begin forming a solid mass and take on a satiny sheen. Solid masses will begin to rise slightly from the top surface of the block, and may develop some reddish or brown coloration. To grow the shelf form, cut the hole in the end of the bag after at 30 days of incubation, before much energy has gone into masses forming on the top of the block.

Why cut the bag open before primordial mounds form?

The block will tend to grow in the presence of fresh air, light, and moisture. By creating an opening you can get the block to form primordial mounds where you want the mushrooms to grow.

How do I know the mushrooms are ready to harvest?

The reishi fruiting bodies will keep growing until ready to produce spores. The spores emerge from the pores on the underside of the shelf formation, but drift upward and settle on the top of the shelf. When you see some rusty-brown dust accumulating on tope of the shelf, it is ready to harvest.

How do I harvest the mushrooms?

You can pull them off the block, or cut the stems close to the surface of the block.

How should I store the mushrooms?

You usually dry Reishi mushrooms before using them. You can use a dehydrator or just in the open air in the sun, if weather permits. Drying them pore-surface-up in the sun will increase their vitamin D content. Cutting them in slices before drying them makes the easier to work with once dried.

How should I use Reishi mushrooms?

People make Reishi water infusions (tea or broth) or alcohol extractions (tinctures). Each has a different set of medicinal and nutritive properties. As for how to use them medicinally, that is a complicated topic that you will have to research for yourself. If you are currently under medical treatment for cancer or any serious condition you should definitely let your doctor know if you are using Reishi.

How do I make a water infusion?

You make a Reishi water infusion, or tea, simply by soaking some of the dried material in boiling water, or boiling it in water for a few minutes. Use about a teaspoon of finely ground reishi, or slightly more coarsely broken chunks, in a cup of water for a nice mushroomy-flavored beverage or broth. You can drink it immediately or refrigerate it for use later. You can cook with it, or try mixing it with other teas, or coffee.

How do I make a Reishi tincture?

You make a Reishi tincture by soaking a quantity of reishi in grain alcohol, such as non-flavored vodka or food- or medical-quality ethyl alcohol, for a period of time. A teaspoon of reishi in two or three ounces of vodka will produce a deeply flavored and colored fluid in a few days. Some recommend letting it soak for a month.

What about using Reishi tincture in cocktails or cooking?

That sounds like an excellent topic for research and experimentation!

Can I start another container of substrate with the block when it's finished?

Reishi mycelium, like the fruiting body, gets extremely tough, almost like a block of wood. It really doesn't lend itself to use as spawn when it has matured to the point of fruiting.

If the block has stopped fruiting can I restart it by putting it outside?

Reishi does well growing outside, even in relatively cold climates like ours. It often works, to put the block outside on the ground in the shade where, if kept moist, it will usually fruit again, though producing less fruiting body than before. It will only grow in warmer, wetter weather, but it proves surprisingly hardy over winter and withstands a degree of drought.

What other factors should I consider for growing this mushroom outside?

You should let your block incubate in the shelter and shade of a building, but when fruiting the mushroom will enjoy the open air during the growing season. In the wind and heat you will need to water the bag frequently, spraying it with a hose or using a watering can. Keep it out of direct sun.

Can I use the GIY kit to grow sawdust spawn to inoculate additional substrates?

Yes! Just omit any coffee grounds and take special care to avoid contaminants. The mycelium will still tend to start fruiting in two or three weeks so use the colonized substrate as spawn before it starts thickening into primordia. It will make about 5 lbs of spawn, about a gallon in volume.

Can I make the kit ingredients go further than just the one bag?

Yes! Once you have gone through the process and learned a bit about the containers and substrate materials that work with the peroxide method, you can easily extend a GIY kit to two or three times its normal volume. You can also use reusable or biodegradable growing containers, reuse the poly growing bags – there are lots of possibilities!