Growing Mushrooms the Easy WayHome Mushroom Cultivation with Hydrogen Peroxide

An instruction manual in two volumes based on the use of peroxide in mushroom cultivation, by R.R. Wayne, Ph.D.

Now translated into Spanish - Romanian

And announcing:An entirely new approach to mushroom growing

Non-Sterile Mushroom Cultivation

Mushroom growing - a great pastime, but...Mushroom growing has the potential to be a fun and fascinating pastime. Our forests have provided many species of fungi that are both beautiful and delicious, and learning to cultivate them can revive our connection to nature and the earth. But if we have to buy a lot of equipment to sterilize substrate and clean the air of contaminants, growing mushrooms can lose its romance. And it can get absurdly complicated when cultures keep spoiling, despite our most elaborate precautions.

Simplify! So why use hydrogen peroxide in mushroom growing? Hydrogen peroxide simplifies the whole process of growing fungi. There's no need to build a sterile laboratory, buy a special giant pressure cooker, or even construct a glove box. A low concentration of peroxide keeps out the contaminants, while allowing healthy growth of mushroom tissue. And as the mushroom tissue grows, it converts the peroxide to water and oxygen, leaving a clean, vigorous mushroom culture.

Growing Mushrooms the Easy WayI performed my first experiments to test the peroxide idea in 1993, and it worked. Although the invention was patentable, I decided instead to offer the information to the public in the form of an instruction manual. The manual, now in two parts, is entitled Growing Mushrooms the Easy Way, Home Mushroom Cultivation with Hydrogen Peroxide. It is the product of nearly seven years' experimentation to perfect the procedures and find new applications for the peroxide method. The manual in all editions is now in the hands of mushroom growers in 80 countries around the world. In stepwise directions, the peroxide manual explains how to:

Grow mushroom cultures in an ordinary room.

Handle cultures in the open air in a kitchen or non-sterile workshop. Protect cultures from bacteria, yeast, mold, and mushroom spores. Prepare mushroom cultures without an autoclave. Prepare bulk fruiting substrate at room temperature, without heating and cooling. Do away with costly filter-patch culture bags; use ordinary trashbags instead. Prepare sawdust-based mushroom spawn medium with just a ten minute steaming. Grow mushroom spawn and agar cultures on a bookshelf or in a closet.

Contents

Slideshow What's in Volume I of the peroxide manual? What's in Volume II of the peroxide manual? What's this about Non-Sterile Mushroom Cultivation? How do I order the manuals? Growers comment on the Peroxide Method FAQs on peroxide in mushroom growing Try it yourself! List of countries where growers have obtained the Peroxide Manual FAQs on mushroom cultivation Basics of mushroom cultivation Mushroom links, books, and vendors of cultures Updates for users of the peroxide manual Sources of supplies for the peroxide method About the Author

Found a link that's not working? Please e-mail me.

Pouring Agar Plates

Here I'm pouring melted nutrient agar containing peroxide into a set of reusable plastic petri dishes. This is taken in my kitchen, with no air filtration in use. After the agar solidifies and the plates are dried for a few days, they are used for maintaining mushroom tissue cultures. Virtually any commonly cultivated mushroom species can be grown on peroxide-treated nutrient agar

Cutting agar to transfer mycelium

Here I am using a metal X-acto knife, already sterilized in the flame of the alcohol lamp nearby, for cutting a chunk of agar culture from a peroxide plate to transfer the mushroom tissue (mycelium) to a jar of "10-minute spawn" medium, all in the open air of my kitchen. You can see the halo of white mushroom tissue on the plate, although the photograph exaggerates the size of it relative to the size of the plate. The organism is Hericium erinaceus (Lions Mane), a wood decomposer, but other mushroom species can be handled exactly the same way.

Inoculating mushroom spawn

Here I'm inoculating a jar "Ten-minute spawn" medium in the open air with a chunk of mycelium from an agar culture of Hericium erinaceus, using a flame-sterilized X-acto knife for the transfer. A stack of peroxide-treated agar Petri dish cultures sits to the left, inside a plastic food storage bag.

Spawn is essentially a mushroom "starter" culture used to inoculate the final mushroom-producing cultures. The Ten-minute spawn is so-named because it takes only 10 minutes to steam it, compared to at least 45 minutes to sterilize ordinary spawn in a pressure cooker. The medium contains materials chosen to be compatible with peroxide, in this case wood pellet fuel and paper fiber pellets, suitable for cultivation of wood decomposing mushrooms.

Jars of Ten Minute Spawn on a Bookshelf

Here's the bookshelf where I grow my peroxide-treated "Ten Minute Spawn," which will be used to inoculate the final bulk substrate for mushroom production. As always, there is no air filtration in use. The Ten Minute Spawn is a sawdust based medium. Some species are better grown on sterilized grain spawn, which can also be treated with peroxide after pressure-cooking to destroy the peroxide-decomposing enzymes present in the raw grain. There are even forms of grain that can be prepared with a brief steaming much like the Ten Minute Spawn, but these tend to be much more expensive than raw grain.

Some mushroom growing equipment for the peroxide method

Here's some of my basic equipment for the peroxide method: a bag of pellet fuel (in this case oak, from Pennington Seed), a 5-gallon bucket with lid for mixing substrate, a bottle of 3% peroxide solution, and a 500 ml graduated cylinder with a 10 ml measuring pipette inside, for measuring peroxide.

If you are just a beginner at mushroom growing, whether or not you use the peroxide method, you will probably want a pressure cooker for making agar plates (although they can be made, less reliably, without it), jars with lids, a couple of pots for boiling water, an alcohol lamp, a small scale or balance for weighing, some petri dishes, some small boxes, some fresh trash bags, a hand mister, and a cool space. Later you may want a fan and an automatic misting system.

To measure the peroxide concentration in the bottles you get from the store, you will also need a small test tube with a lip, and a balloon. You will NOT need a glove box, HEPA filters, ultraviolet lights, a sterile laboratory, laminar flow hoods, air locks, foot washes, etc. etc.

For some suggestions on obtaining the supplies used in the peroxide manual if you live in the US or the UK, visit my Sources page

Testing peroxide concentration

This shows my simple test for peroxide concentration---necessary because stock solutions can lose their punch. The test tube received a few milliliters of hydrogen peroxide solution, which has now decomposed to release oxygen, filling the balloon. Although you can't see it in this picture, my fingers are holding in

place a fat rubber band wrapped around the mouth of the balloon to keep a tight seal on the tube. Once all the peroxide has broken down, the balloon is carefully removed and the oxygen is measured by releasing it into an inverted graduated cylinder filled with water

Inoculating Pellet Fuel Mushroom Substrate

Here I am, headless, inoculating a 5 gallon bucket of peroxide-treated oak pellet fuel substrate with a jar of elm oyster "Ten minute spawn." As usual, this is taken in my kitchen, with all the action performed in the open air.

Pellet fuel is an ideal substrate for the peroxide method, because it is completely peroxide-compatible, free of enzymes that break down hydrogen peroxide. But pellet fuel is far from being the only substrate that works. You can use straw and similar drainable materials (details in Volume II of the manual), or certain peroxide-compatible porous woody materials such as sawdust-based cat litter (in the UK, Fussy Puss™ litter), additive-free composite logs (in the UK, Clean Heat™ logs), the sawdust derived from milling of kiln-dried lumber, paper fiber pellets (in the US, Crown™ Animal Bedding or Good Mews™ Cat litter), paper pulp, and clean cardboard. Any other porous substrate commonly used for mushroom growth, such as raw sawdust, will work with peroxide if you first pressure-sterilize the substrate, or bake it for several hours at 275-300 degrees F (150 degrees C), or steam it 24 hours, to destroy the peroxide-decomposing enzymes present in it.

Some mushrooms, such as white buttons and their relatives, grow best on compost, which can generally be prepared without peroxide, although I am investigating ways to improve compost making with the help of peroxide.

Bagging Pellet Fuel Mushroom Substrate

Here I'm pouring inoculated, peroxide-treated pellet fuel substrate from a 5 gallon bucket into a fresh plastic "tall kitchen bag" supported by a cardboard box. In some cases, it may be more convenient to add spawn to the bags after filling, rather than before. And there are various alternatives to using bags, such as plastic buckets with loose fitting lids. Of course, some mushrooms may be grown in beds rather than in bags.

This is taken in my kitchen. No HEPA filters or glove box in sight. Jars of "Ten Minute Spawn" in the background.

Mushroom substrate, bagged and sealed

This is what my wood-decomposing mushroom cultures look like after the trash bag is filled with inoculated, peroxide-treated substrate and sealed with a twist tie. I leave the bag in the cardboard box until the mycelium knits the substrate together. There is no filter on the bag for gas exchange, as the thin plastic allows enough oxygen to diffuse through to the culture.

When the culture is ready to form mushrooms, I put a small slit in the side of the bag, and the mushrooms grow out the slit

The Results -- Mushrooms Grown by the Peroxide Method

Enoki and King Oyster mushrooms grown with peroxide by White Rock Creek Mushrooms in Hillsboro, Texas.Photo courtesy of Joe Durham.

Shiitake mushrooms grown with peroxide by White Rock Creek Mushrooms in Hillsboro, Texas.Photo courtesy of Joe Durham.

Lions Mane and Almond mushrooms grown with peroxide.Lions Mane photo courtesy of Joe Durham.

Maitake mushrooms grown with peroxide by White Rock Creek Mushrooms in Hillsboro, Texas.Photo courtesy of Joe Durham.

This is what it is all about!

Peroxide in Mushroom Growing - Frequently Asked Questions

Click the link, or scroll down the page.

What are the additional advantages of the peroxide method? What are the limitations of peroxide use in mushroom growing? What are the different ways a mushroom grower can use peroxide? Can I use peroxide for growing mushrooms on straw or compost? What substrates can I use for mushroom growing with peroxide? What mushrooms can I grow in the presence of peroxide? How effective is peroxide treatment in mushroom cultivation? How safe is peroxide use in mushroom culture? Can peroxide be used for certified "organic" growing of mushrooms? What equipment do I need to grow mushrooms using the peroxide method? Can the peroxide method be used to grow mushrooms commercially? What are the comparative costs of growing mushrooms with peroxide? How do I order the peroxide manual? Mushroom Growing FAQs Mushroom Growing Basics

What are the additional advantages of using peroxide in mushroom cultivation?

With peroxide, you can make sawdust spawn medium from wood pellet fuel with just a ten minute steaming, rather than pressure sterilization. This is one of the fastest methods of making mushroom spawn yet devised. The spawn can then be grown on a bookshelf in your home, rather than in a sterile laboratory. And, the amount of spawn you can make isn't limited by the size of your pressure cooker, since you can use any of a variety of large pots with fitted lids instead.

With peroxide, you can prepare sawdust cultures without pressure sterilizing either the bulk substrate or the supplements. You can even do it without heating the substrate. To do this, you will need to use peroxide-compatible starting materials such as wood pellet fuel and selected nitrogen supplements. Volume I of the peroxide manual describes a simple pellet fuel procedure with a boiling-water pasteurization, and it gives the details on how to select appropriate materials and supplements. Volume II of the manual presents an "add-and-stir" protocol for preparing peroxide-compatible porous substrates such as pellet fuel, paper fiber pellets, and kiln-dried sawdust, using peroxide at room temperature.

Peroxide can do away with costly filter-patch culture bags for bulk substrate. Grow cultures in ordinary trashbags (placed inside boxes) right out of the package, or in reusable plastic buckets with lids.

Added peroxide keeps cultures from going anaerobic (breakdown of the added peroxide by the mushroom mycelium releases oxygen). This makes it possible to pack sawdust-based substrate more tightly, creating a denser substrate favored by many species.

Peroxide kills mushroom spores, so you can grow agar cultures in the same building you use to fruit your mushrooms, even if the mushrooms produce a high spore load.

Peroxide kills contaminants without encouraging new resistant strains. (Antibiotics, sometimes added to agar medium, kill only bacteria, and can select for antibiotic resistant mutants).

Hydrogen peroxide in 3% solution is inexpensive, odorless, non-volatile, non-allergenic, low toxicity, non-irritating, stable, readily available, easy to handle, mechanically dispensable, entirely biodegradable, and environmentally benign.

What are the limitations of peroxide use in mushroom growing?

Enzymes in raw sawdust will destroy peroxide in short order. Therefore, something has to be done to eliminate these enzymes before peroxide can be usefully added to sawdust. With current technology, this means pressure sterilizing. However, wood pellet fuel, paper fiber pellets (e.g. Crown™ Animal Bedding or Good Mews™ cat litter, etc.), and some kinds of kiln-dried sawdust can accept peroxide without pressure sterilizing, baking, or prolonged steaming. Wood pellet fuel is sawdust that has been made into hard dry pellets that can be burned in special pellet stoves.The heat and pressure used to create such pellets destroys the peroxide-decomposing enzymes. Clean newsprint, cardboard, and paper pulp can also accept peroxide as can the woody material in composite logs, and probably also the sawdust derived from milling of kiln-dried lumber. Finally, a number of "drainable" materials can be prepared readily with peroxide despite the enzymes. These materials include straw and similar plant remains, seed and nut hulls, and wood chips (see Volume II of the manual for details).

Because of their enzyme content, most soft-textured raw nitrogen supplements (such as bran, cornmeal, cottonseed meal, etc.) still need to be baked or pressure sterilized before adding them to peroxide-treated bulk substrate. However, certain processed supplements, which lack the peroxide-decomposing enzymes found in traditional supplements, do not have to be baked or pressure sterilized (see Volume I of the manual for details). Instead, they can be mixed with the substrate and treated with it. Also, my recent research has shown that steel cut oats can be used without sterilization despite their enzyme content, to enrich substrate for oyster mushrooms following the "Add-and-stir" procedure in Volume II of the peroxide manual.

In some circumstances, using the peroxide method prevents use of commercial spawn. For mushroom mycelium to grow in the presence of peroxide, it must be adapted to peroxide at a low concentration, usually by incubation of a sample of mycelium on peroxide-treated nutrient agar for a period of roughly two weeks. Without this adaptation process, peroxide will strongly inhibit or even kill mycelium at the concentrations used to prepared bulk substrate. But when properly adapted, the mycelium grows freely in peroxide-treated bulk substrate. Spawn sold commercially has generally not been adapted to peroxide, so it will normally fail to thrive when inoculated into peroxide-treated substrate. There are, however, certain exceptions to this rule. For instance, those materials which contain active peroxide-decomposing enzymes, such as straw and similar drainable "raw" substrates, can be pasteurized with a peroxide soak and then inoculated with commercial spawn. In these substrates, the peroxide will disappear by decomposition sometime after the grower drains off the soaking solution, allowing growth of the non-adapted mycelium in the peroxide-treated substrate..

If you want to germinate mushroom spores, it is best to start them first on non-peroxide medium and then transfer the mycelium to peroxide agar. Procedures for doing this are now included in Volume II of the peroxide manual.

There are two drawbacks of peroxide for liquid culture. One is that blenderized mycelium has to be used to inoculate liquid cultures. Blenderizing releases peroxide-decomposing enzymes previously encapsulated in the mycelial cells, causing peroxide to decompose in the medium. The other drawback is that, assuming one could overcome the first problem, the peroxide concentration will steadily fall as mushroom tissue circulates through the medium during the course of ordinary growth, decomposing peroxide as it goes.

The procedures described in Volume I of the peroxide manual are scaled to hobby use, and some may prove awkward to use on larger scales, or they may not work at all at those scales. Nevertheless, for growers interested in the commercial applications of the peroxide method, Volume II of the manual contains substrate-preparation procedures designed for any scale of use.

What are the different ways a mushroom grower can use hydrogen peroxide?

1) For petri dish cultures of mycelium: add peroxide to your agar medium. No need for glove boxes or sterile facilities to keep out contaminants. Use the resulting cultures to inoculate spawn and to maintain the mycelium.

2) For spawn making: add peroxide to your spawn medium. No need for a laminar flow hood or a spawn laboratory. Sawdust spawn made from pellet fuel cooks in ten minutes. Use the resulting spawn to inoculate sawdust, compost, straw, logs, etc.

3) For bulk substrate, if you don't have an autoclave. Prepare straw and similar substrates by a simple soak-and-drain procedure (procedure described in Volume II of the manual). Add peroxide to supplemented wood pellet fuel substrate or other peroxide-compatible materials (procedures described in both volumes of the

manual). No need for heat-resistant space bags. Use the resulting cultures for fruiting mushrooms, or break them up and use as spawn to inoculate straw, compost, logs, etc.

4) For bulk substrate cultures, if you do have an autoclave (or if you plan on baking or lengthy steam pasteurization). Add peroxide to your own favorite substrate mix at the time of inoculation. No need for air filtration, reduces overall rate of contamination.

Can I use peroxide to grow mushrooms on straw or compost?

Yes. Although straw contains peroxide-decomposing enzymes that will rapidly do away with any peroxide you add, my recent experiments show that straw (and presumably other similar drainable substrates) as well as pelleted straw, can be prepared very easily by room temperature methods using peroxide, despite the enzymes. The most recent procedures for whole straw are incorporated into Volume II of the manual.

There is little use for peroxide in preparation of compost. This is because compost is by nature not a sterile substrate. Properly made compost should have a tremendous diversity of microorganisms in it, even after it heats up to temperatures high enough to kill insects and weed seeds. This diversity of microoganisms should protect the mushrooms from molds and pathogens. The appearance of significant mold growth during the colonization of compost by mushroom tissue is a likely sign that the compost lacks an important set of microorganisms, perhaps because it was allowed to get too hot. Although one might be able to control such mold or pathogen growth with peroxide, a better solution is to correct the procedure for compost preparation. See Dr. Elaine Ingham's fascinating website, Soilfoodweb.com for more information on what makes good compost.

If compost (or straw) is your preferred substrate, however, you can still use peroxide to maintain agar cultures and prepare spawn.

In addition, most mushrooms that grow on straw or compost will also grow on wood pellet fuel or similar peroxide-compatible materials prepared by the peroxide method (as are the almond mushrooms shown below) although the overall yield may be lower for some species.

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What substrates can I use to grow mushrooms with peroxide?

You can use straw and similar drainable materials, wood chips, and nut and seed hulls (details in Volume II of the manual), or certain peroxide-compatible porous woody materials, such as wood pellet fuel (sawdust made into hard dry pellets), pelleted straw, sawdust-based cat litter (in the UK, Fussy Puss™ litter), additive-free composite logs (in the UK, Clean Heat™ logs), the sawdust derived from milling of kiln-dried lumber (oyster mushrooms only), paper fiber pellets (in the US, Crown™ Animal Bedding or Good Mews™ Cat litter), paper pulp, and clean cardboard. Any other porous substrate commonly used for mushroom growth, such as raw sawdust, will work with peroxide if you first pressure-sterilize the substrate to destroy the peroxide-decomposing enzymes present in it.

What mushrooms can I grow in the presence of peroxide?

King Oyster mushrooms (Pleurotus eryngii) grown by the peroxide method at White Rock Creek Mushrooms in Hillsboro, Texas. Photo courtesy of Joe Durham.

Every mushroom species I have tested can be grown in the presence of peroxide, and it is highly likely that any mushrooms that otherwise can be cultivated can be grown this way. I personally have used peroxide successfully to keep agar cultures and prepare spawn of Pleurotus ostreatus (oyster), Pleurotus eryngii (King Oyster), Agaricus subrufescens (almond mushroom), Hypsizygus ulmarius (white elm mushroom or elm oyster), Hypsizygus tessulatus (shimeji), Coprinus comatus (shaggy mane), Lentinula edodes (shiitake), Hericium erinaceus (Lions' Mane), and Grifola frondosa (maitake). Others have used peroxide to grow Psilocybe species (in countries where it is legal to do so), Reishi (Ganoderma lucidum) and morel mycelium.

The mushroom species I have grown most often are H. erinaceus, H. ulmarius, P. eryngii, and A. subrufescens. Each has different characteristics and requirements. I am not a shiitake grower, but others have used the method to grow shiitake successfully. Agaricus species such as crimini, white button mushrooms, Portabellos, the almond mushroom, and the almond portabello (Agaricus blazei) can all be grown with the help of peroxide for agar culture and spawn making. There is little practical use for peroxide in the production of compost, the favored substrate for these species, but straw can be readily prepared with the help of peroxide, and some may find it acceptable as an alternative to compost in Agaricus cultivation.

How effective is peroxide treatment in mushroom growing?

I am currently able to grow grain or sawdust spawn consistently without contamination, the only exceptions being gross errors on my part (getting my finger in the container, or dropping a lid, etc.) or undetected spoiling of certain ingredients. With agar cultures, I get occasional mold colonies, usually only on older plates at the edges where the peroxide has largely disappeared. With bulk substrate, my success rate in preventing contamination currently runs around 99% when I follow the protocols set forth in the manual, although it was lower in the early days of my experimentation with peroxide because of my own inexperience with mushroom growing.

How safe is peroxide use in mushroom culture?

The peroxide added to mushroom cultures decomposes entirely to water and oxygen as the mushroom mycelium occupies the substrate. As a result, there can be no trace of the added peroxide left in the mushroom crop, beyond what is naturally there due to metabolic processes. Moreover, hydrogen peroxide itself is found naturally in all aerobic living organisms and in a variety of natural environments. From time immemorial, honeybees have secreted enzymes which add peroxide to their nectar, protecting it from bacteria, yeasts, and mold, and imparting antibacterial properties to the resulting honey. The mycelia of certain mushrooms produce their own peroxide to help break down the woody substrates the organisms encounter. And peroxide is even a part of the healing defenses of the human organism. Indeed, around the world, thousands of proponents of a system of healing called oxygen therapy ingest peroxide solution on a daily basis to cure various ills and promote vitality, and some people have done so for many years. Much of the peroxide found in nature is created spontaneously by ultraviolet light falling on water.

There is some question as to the effect peroxide oxidation may have on the mushroom substrate itself. Chlorine, when it reacts with organic materials like paper pulp, produces small amounts of dioxin, a very dangerous, cancer-causing chemical. Hydrogen peroxide does not produce dioxin, and as a result, environmentalists are campaigning to get paper companies to bleach their paper fiber with peroxide rather than chlorine. Still, it is conceivable that peroxide could produce some other harmful substance when it reacts with the organic materials in mushroom substrates. I have not ruled out this possibility, but I consider it unlikely. For one thing, living organisms have evolved for millions of years with hydrogen peroxide both in and around them. This means that aerobic organisms most likely have developed metabolic machinery to deal safely with the oxidation products that result from the reaction of peroxide with biological materials. In addition, hydrogen peroxide is chemically quite stable in sterilized mushroom substrates, and the concentration of peroxide we're using is so low that the amount of substrate oxidation going on has to be very low indeed. Finally, I have seen absolutely no evidence of any mutagenic or toxic effect of peroxide-treated mushroom substrate on the mycelium or fruiting bodies. Agar cultures containing hydrogen peroxide give fine, healthy halos of mycelium, and the final fruiting cultures produce mushrooms as beautiful as any grown by traditional methods.

Can peroxide be used for certified "organic" growing of mushrooms?

Organic certification standards vary from one place to another. So far, I have heard from one correspondent that peroxide is acceptable for organic growing in Ontario, Canada, and another correspondent tells me that peroxide is allowed as a "disinfectant" for organic certification in British Columbia, Canada. I have not yet heard opinions from certifying organizations in any other locations.

What equipment do I need to grow mushrooms using the peroxide method?

Handling and measuring the peroxide itself requires only a measuring pipette (10 ml volume) and a graduated cylinder (probably 100 ml volume). To measure the peroxide concentration in the bottles you get from the store, you will also need a small test tube with a lip, and a balloon. You will NOT need a glove box, HEPA filters, ultraviolet lights, a sterile laboratory, laminar flow hoods, air locks, foot washes, etc. etc.

Preparing and handling bulk pellet fuel substrate by the methods described in the peroxide manual requires a covered pot for boiling and cooling water, a second pot such as a teapot to boil water for pasteurizing containers, and a larger container such as a five gallon plastic bucket with a tight-fitting lid.

If you are just a beginner at mushroom growing, whether or not you use the peroxide method, you will probably want a pressure cooker for making agar plates (although they can be made, less reliably, without it), jars with lids, an alcohol lamp, a small scale or balance for weighing, some petri dishes, some small boxes, some fresh trash bags, a hand mister, and a cool space. Later you may want a fan and an automatic misting system.

For some suggestions on obtaining the supplies used in the peroxide manual if you live in the US or the UK, visit my Sources page.

Can the peroxide method be used to grow mushrooms commercially?

Golden Trumpet mushrooms grown by the peroxide method at White Rock Creek Mushrooms in Hillsboro, Texas. Photo courtesy of Joe Durham.

Yes. Volume II of the peroxide manual presents two peroxide methods for preparing bulk mushroom substrate in any quantity at room temperature. These methods are well suited to commercial cultivation. Both volumes of the manual present peroxide methods for maintaining tissue cultures, storing strains, and preparing mushroom spawn, all crucial aspects of commercial cultivation as well.

What are the comparative costs of growing mushrooms with peroxide and pellet fuel?

Pellet fuel costs about $3.00-4.00 retail per 40 lb. bag in my area of the US, but it is also possible to get discounts for large quantities, and I have bought oak pellet fuel for $120 a ton (50 bags). This works out to about $0.06 a pound dry weight, or $0.12 to $0.14 per mushroom block. This is a significant expense if you can get sawdust for free. However, if you are using pellet fuel with peroxide, you can use ordinary trash bags to hold your substrate, rather than the special heat resistant space bags usually used for pressure cooking sawdust. I pay $0.04 each for trash bags from the grocery store, whereas heat resistant bags cost anywhere from $.80 each (if you buy just a few for hobby use), down to $0.15 each (if you buy them in great quantities for commercial use). In addition, with boiling water pasteurization of pellet fuel, you avoid lengthy pressure sterilization (or lengthier steaming), so your energy costs are very low. Your amortized cost of equipment is also very low, especially compared to the costs of air filtering equipment and pressure cookers, autoclaves, or steam chambers. Finally, you can easily make your own spawn without a laboratory using the peroxide method, perhaps saving you the cost of the lab or the purchase price of spawn ($10 to $20 for every five to six pounds).

All told, my blocks cost about $0.33 each, including pellet fuel ($0.14), lime ($0.01), supplements ($0.06), peroxide ($0.05), my own spawn ($0.02), bags ($0.04), and energy use ($0.01?). This compares to estimates I have seen ranging from $1.25 to $2.50 per block for shiitake cultivation with traditional methods (for example, Albert Bates of

Mushroom People wrote an article on shiitake production for the Fungus Digest--now defunct--that estimated $2.50 per block). Perhaps some of this difference should be balanced against the experimental nature of the peroxide substrates, which may take time to optimize for yields comparable to traditional substrates. But this in turn should be balanced against the reduced contamination rate that can be expected using peroxide, even when compared to commercial set-ups using expensive contamination control systems.

Growing Mushrooms with Hydrogen Peroxide -- Try It!

Try it yourself. Add 6 to 8 mls 3% hydrogen peroxide to one liter of your favorite agar medium. (To make sure your peroxide solution still has some punch, pour a little into a small glass and add a bit of banana. The solution should fizz vigorously). First pressure cook the medium for the standard length of time, then let the hot agar cool down, until you can handle the container comfortably. Sterilize a measuring pipette or steep it in boiling hot water for a minute, then cool, before using it to transfer peroxide. After adding peroxide to the agar, mix it in thoroughly with a swirling motion. Then pour your plates. (Petri dishes should be sterile).

When your plates have solidified, take the tops off a couple of them and let them sit in the open air for a while, perhaps an hour. Then close them up and incubate for a week or two. See any colonies? Meanwhile, inoculate some of the other plates with your favorite mushroom mycelium. You can work in the open air, but you'll still need to flame your scalpel as you ordinarily would. Wrap the inoculated plates in a plastic "food storage" bag and incubate. Check back in a week or so. How are they doing?

For best results with regular use, you'll need to measure the actual concentration of peroxide in your solution, to make sure that you have enough, and that you're not overdosing your cultures (I use different concentrations for spawn and bulk substrate). You'll also need to "clean" the mycelium of occult contaminants that build up after a few transfers, or else you'll eventually be transferring bacteria instead of mycelium. I describe the proper procedures in detail in the peroxide manual.

Mushroom GrowingFrequently Asked Questions

Click the link or scroll down. Can morels be cultivated? How can I grow them? I want to grow chantrelles, Boletus edulis, matsutake, or truffles. How can I do it? I want to start a mushroom growing business. How feasible will it be? I live in a hot climate. What mushrooms can I grow? How long does it take to grow mushrooms? What books are there that tell how to grow mushrooms?

Can morels be cultivated? How can I grow them?

Yes, mushroom growers have worked out ways to cultivate morels, but these mushrooms are still among the most difficult to grow, at least in any quantity. For outdoor growing, some companies are selling morel "kits." With these, you prepare an outdoor space according to specifications and inoculate with morel spawn. Then, if you are lucky and weather conditions cooperate, you may see morels the following season. Agar cultures of morel mycelium and morel spawn can both be prepared by the peroxide method following the same procedures used for other mushrooms. Morel spores germinate very quickly, and the mycelium grows faster than virtually any other mushroom mycelium, covering an agar plate in 3 days or so. But the difficulty with morels is getting the mushrooms to form.

I want to grow chantrelles, Boletus edulis, matsutake, or truffles. How can I do it?

All of these species require association with a live tree to produce mushrooms, which makes them poor candidates for cultivation. Of these four, only chantrelles have been grown "in captivity," and then only by heroic measures which the hobbyist will not likely duplicate. There is also little evidence that any of the first three of these species can be deliberately introduced into a chosen outdoor plot where they are not already growing, either by spore slurries or mycelial transfer. The one exception is truffles, where tree seedlings have been successfully inoculated with spores from European truffles, and the trees have been grown to

maturity in the US, eventually producing truffles. (For information on acquiring truffle tree seedlings, visit www.truffletrees.com.) There is also some indication that Oregon white and black truffles can be introduced into suitable groves of Douglas fir trees by spore slurry inoculation. But because of unsuitable weather conditions for truffle growth in Oregon recently, it may be a number of years before this possibility can be clearly confirmed or disproven.

I want to start a mushroom growing business. How feasible will it be?

The business of mushroom growing is not a simple one. Although it is easy to grow a few mushrooms for home consumption, it is far more difficult to grow a large number of mushrooms for commercial sale. The reasons include problems of maintaining reliable supplies of substrates and supplements, regulating climate and ventilation, excluding insects and rodents, keeping equipment functioning, dealing with waste, excluding contaminants, maintaining production schedules, keeping stock cultures healthy and viable, and managing space requirements, among others. And even if you succeed in growing the kind of crop you need to make money, you may run into other obstacles like high insurance prices and unreliable markets. So, to be successful at mushroom growing, you need to be determined and you need to be good at improvising and solving problems. For more on the business of mushroom growing, visit the web site of the Mushroom Growers' Newsletter.

I live in a hot climate. What mushrooms can I grow?

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There are several commonly cultivated strains of mushrooms that grow well in hot weather. The Paddy Straw mushroom, Volvariella volvacea and its close relative Volvariella bombecina, grow best at temperatures between 75 and 95 degrees F (24-35 degrees C). The medicinal Reishi mushroom, Ganoderma lucidum, prefers warm weather (75 degrees F/24 degrees C), and the Florida oyster, a strain of Pleurotus ostreatus, fruits at temperatures above 75 degrees F (24 degrees C). The almond mushroom, Agaricus subrufescens, is a warm grower, although the mycelium should not get above 90 degrees F. The King Stropharia, Stropharia rugosa-annulata also fruits only when temperatures rise. Beyond that, there may be mushrooms native to your area that people are cultivating. Ask around!

Although these mushrooms can all do well at warmer temperatures, remember that they all still need significant humidity.

How long does it take to grow mushrooms?

The answer to this question depends on several things, including the stage of mushroom growing you want to start with, the method of inoculation, the temperature, the kind of substrate you are using, the mushroom species, and the specific mushroom strain. Starting at the very beginning, mushroom spores can take from a few hours to several days to germinate. A culture of mushroom mycelium growing on a petri dish of nutrient agar can take 24 hours (for morels) to upwards of

a month (for Agaricus species and Stropharia Rugosa-annulata, for example) to spread across the better part of the plate. Using a chunk of agar culture to inoculate small jar of spawn, it can take 2-4 weeks for the spawn to reach maturity (1-2 weeks if you inoculate the spawn with other spawn). If you start with a quantity of spawn and fresh bulk substrate, it takes about two to three weeks for standard oyster mushrooms to reach fruiting stage, and a similar length of time for Lions Mane (although I prefer to incubate them longer before letting them fruit), whereas the Elm Oyster takes six weeks, and shiitake can take longer. (This all can be accomplished more quickly using liquid inoculation techniques). If you start with a ready-made kit, already grown-through with mushroom mycelium, it can take from a week to a month for mushrooms to form, depending on the species. (Thicker, fleshier mushrooms tend to form and mature more slowly than others.) In general, of course, the more optimum the substrate, the temperature, and any other relevant growing conditions, the faster the mushroom mycelium and the forming mushrooms will grow.

What books are there that tell how to grow mushrooms?

Growing Gourmet and Medicinal Mushrooms, 3rd Edition by Paul Stamets. This new edition of Stamets's definitive text has been expanded by over 150 pages compared to the 2nd edition. Covers cultivation of 31 species, from oyster mushrooms (several chapters) to shiitake to portobellos. This is the best available book on cultivating wood decomposing mushrooms by traditional (that is, non-peroxide) methods.

The Mushroom Cultivator: A Practical Guide to Growing Mushrooms at Home, by Paul Stamets and J.S. Chilton. This book is somewhat dated, but still the best reference available on growing Agaricus and other compost-loving species by traditional methods.Shiitake Growers Handbook : The Art and Science of Mushroom Cultivation by Paul Przybylowicz and John Donoghue. If you are going to grow shiitake mushrooms, you should definitely have this book in your collection.