Cultivation Quarters

Ken Litchfield ©April 2017

About the Garden Giant Mushroom
The Garden Giant is the easiest, most satisfying mushroom for the average beginning or experienced mushroom gardener to grow. Its scientific name is Stropharia rugoso-annulata Farl. ex Murrill and its family is the Strophariaceae. Its best-known common name is Garden Giant because it can get quite huge, a foot or more across the cap, and hefty in poundage. It is also known as the King Stropharia because it is the largest of the Stropharias and quite regal in appearance, similar to a King Bolete, but with gills. It is also called the Burgundy Cap or Wine Cap because when young and fresh, with the edges still turned down button mushroom style, it is a dark burgundy or maroon-purple that suggests a dark wine. It fades to a lighter tan as the cap matures and flattens out, looking reminiscent of an Agaricus portobello mushroom. Rather than the dark chocolate brown spore bearing gills under the cap of the Agaricus portobello, under the Garden Giant cap are gills that have a dark blackish purple cast characteristic of the Strophariaceae family of mushrooms which also include the Psilocybe magic mushrooms. The Garden Giant mushroom doesn’t stain blue when you rub or bruise the stem like a Psilocybe, with which it has been classified in the past, but it does have a tan veil or skirt around the stem the same color as the stem that often falls away as the mushroom enlarges. The veil connects the edge of the cap to the stem protecting the gills when the cap is still young, similar to young Agaricus button mushrooms where the veil protects the young pink gills. In the Garden Giant this veil or ring often has ridges or wrinkles giving it a rugged appearance, hence the name rugoso-annulata.

The Garden Giant’s favorite place to grow is in your wood chip or straw mulch. It produces regular looking capped mushrooms with gills underneath that look and taste like large tight store bought Agaricus button mushrooms when small, and big flat portobello mushrooms when fully mature. When you harvest this mushroom all you have to do mushrooms in sautés, sauces, or soups. Or if it has matured it can be grilled like fully developed portobellos, which are Agaricus button mushrooms that have fully unfurled. The Garden Giant is similar in many respects to Agaricus button mushrooms with the one major difference being that Garden Giants like to grow on raw cellulose materials like straw and wood chips, whereas Agaricus button mushrooms are grown on compost or manure, basically cellulose broken down by digestion of a grazing animal or by composting, or by digestion of raw cellulose by the Garden Giant.

You can grow both compost feeding mushrooms and mulch feeding mushrooms in the same garden bed; the Garden Giant grows in the raw cellulose mulch of your garden and Agaricus button mushrooms or Shaggy Manes or Shaggy Parasols grow in the composty soil under the mulch produced by the Garden Giant digesting the mulch into compost.

Propagation
It is very easy to propagate the Garden Giant mushroom. Just plant that cut bulbous base of the harvested mushroom with the white fuzz and wood chips hanging off the bottom in fresh damp mulch like it is the bulb of a plant and it will grow into the fresh mulch. You can also lift up a matted layer of mycelium and transplant it to a freshly mulched bed of damp wood chips.

Mycoremediation
Besides growing the mushrooms for food, you can use the fuzzy white mycelial body to break down your wood chip or straw mulch into rich composty garden soil. And if you have heard of bioremediation, this is one of the main mushrooms that makes a mycelial mat in wood chips that can filter and eat bacteria in contaminated runoff from grazed pastures and restore or remediate the health of the land. Once you have it growing in your garden or on your farm, all you have to do is keep it fed regularly with properly applied fresh wood chips or straw mulch and it will continue breaking it down, building your soil, remediating the soil, and providing you with mushrooms like a pet livestock blob, especially if you already are familiar with organic gardening methods, and primarily mulch methods.

Getting Started with Your Garden Giant Spawn Bag from Far West Fungi Farm
The bag of garden giant spawn is about 5 lbs of damp sawdust with some extra nutrients and the Garden Giant mycelium growing in it. The mycelium, also known as hyphae, is the white fuzz that makes up the body of the fungus that produces mushrooms. This fuzz or mycelium impregnated in its substrate food is called spawn and is not spores, which are dustlike unicellular “seeds” that are produced from the fruiting mushroom.
The spawn growing in the bag is isolated from the outside world as a sterile culture and it breaths air through the filter patch on the side of the bag. It can stay in the bag for several days to several weeks before you plant it but it is best during that time to keep it cool or refrigerated to slow down the mycelial metabolism.

This is the material that you are going to add to more food substrate for the mushroom mycelium to eat and enlarge or “ramp up” into more mycelium. The mycelium is the part of the mushroom body that corresponds to the “apple tree” with plant gardening. When the mycelium fruits or produces a mushroom, this is the “apple.” You could fruit the Garden Giant right out of the bag similarly to getting an Amarylis bulb to bloom from the buds stored in the dormant bulb, but it is better to grow the bag of mycelium to a larger size by “ramping up” the mycelium. This is done by adding the bag of mycelium to more food substrate that the mycelium likes to eat. The mycelium will invade and incorporate the new food to be a part of its body by running its digestive tentacles through it like a tentacled blob, which is why we sometimes say that the Fungi are the Kingdom of the Blobs. They aren’t plants or animals but have characteristics similar and different to those kingdoms. Your plastic bag contains a mycelia tentacled blob waiting in the bag to be allowed out to start extending out its tentacles and eating into the raw cellulose of the mulch in your garden bed.

The Structural Food Substrate for the Garden Giant
Substrate is the word used by mushroom growers to refer to the material that the mycelium feeds on and that provides the structure to the mycelial body of the fungus. Primarily, this is compost or manure for humus or duff loving Agaricus button mushrooms and raw cellulose for tree trunk heartwood feeders like oysters, reishi, lion’s mane, and maitake. In the wild the Garden Giant tends to feed on thatch and other raw cellulose, so it isn’t usually found on trees. Raw cellulose substrate or compost/manure substrate for mushroom mycelium is similar to the soil being the substrate for the roots of plants to grow in. Soil provides oxygen, moisture, nutrition, and support for the roots of the plant similar to the rootlike mycelium of the fungus. The tops are different for plants in that they have leaves with chlorophyll for photosynthesis, so they need to be in air and sunlight. The air and sunlight are the “substrate” for the plant’s tops.

The Garden Giant’s favorite food substrate is raw cellulose like landscaper wood chips, or aspen wood shavings from a pet store (already baked sterile), or straw from a straw bale, or sawdust from a carpentry shop, shredded unwaxed cardboard or egg cartons, layered or wadded burlap bags, or combinations of those. Wood shavings or straw used for stable bedding works if there isn’t so much manure in it or if you remove most of the manure and soak the straw to leach out the urine and manure fertilizer which can be poured into garden plants like manure tea. Then the leached shavings or straw can be used for the garden giant.

It is best to soak the substrate material in water to penetrate into the chips, shavings, dust, straw, cardboard, etc. This might be for a few minutes or an hour for dust, shavings, straw, cardboard, burlap, or overnight for chips. (See “Neutralizing Chloramine in Municipal Tap Water” below for the information about neutralizing the antibiological chloramine in your tap water if that is what you will be using to soak your substrate.) It is best to not leave the substrate submerged for longer than 24 hours at a time, so it doesn’t become anaerobic. (For a sustainable anaerobic method of sterilizing your substrate see “The Anaerobic Sauerkraut Method of Sterilizing Substrate” below.) After soaking, the material should be well drained so it isn’t soggy, just damp. The material is best if it is chips or shavings or straw by themselves or mixed in equal parts. With sawdust it is best to mix that with chips and/or straw to open up the texture so it has more air in it, as straight sawdust can become too compacted by itself. Generally, chips that range from the size of little finger joints to thumb or big toe joints mixed are good, and also if those are mixed with shavings and or straw.

Many people worry that the wood chips need to be hardwood like oak or maple or sycamore etc. and that supposedly you can’t use conifer “softwoods” like Monterrey cypress, Monterrey pine, or Eucalyptus that are the main woodchips available from tree trimmers in the bay area. These are considered to have antibiological oils in them. However, Garden Giants and Oyster mushrooms are used in mycoremediation of oil spills and these oils are simply hydrocarbons like cellulose that they can break down and use for food. The wood chips begin volatilizing the oils into the air as soon as they get chipped and are leached of oils after a few waterings or rains on them in the garden anyway. You can also soak fresh woodchips a couple times overnight if you are worried about this.

More important is to use chippy wood chips of whatever species as this is from the internal sterile heartwood of the tree which is more pure raw cellulose and doesn’t have as many organisms for the mushroom mycelium to compete with as there would be with leafy, twiggy, and barky materials that have all kinds of organisms living on the outside of the tree.

Once you have the substrate prepared you can then use it in a number of methods like mother beds or worm bins to “ramp up” the mycelium to larger quantities.

“Mother Bed in the Garden” Style of Ramping Up
For this method you need a garden space of about 4’ by 4’. It is best to situate it in the wind-blocking corner of a fenced garden under a shade tree where the mother bed is less likely to dry out quickly in the sun or wind. The space is ideal if it is too shady to grow most other garden plants anyway. Fungi don’t photosynthesize and they only need a small amount of light for directional fruiting. If your space is sunnier that is OK. You can shade it and keep the wind out by tenting a layer or more of burlap over it on stakes or poles staked around the bed. You’ll need enough substrate to make a layer of substrate 6” to a foot deep or more in the 4’ x 4’ space.

You can dig up and turn the soil in the spot, so it is fluffed with air and the weeds chopped in with the digging. You could also just lay down several layers of unwaxed cardboard over the bed to smother weeds and provide more raw cellulose for the mushroom to eat. If the bed is sunny and you want to use it as a garden for growing plants, it is best to dig up the area and fluff it rather than lay down cardboard as the resulting soil will have a bottom zone of compacted soil, a transition zone of cardboard that will take time to break down, and then the rich soil built by the Garden Giant on top. If you go ahead and dig up and fluff the existing soil, and leave out the cardboard, the worms will be able to come up from below into the fluffed and oxygenated soil. They will continue rototilling it and mixing in the bottom of the mulch layer into the top of the soil layer in a continuous transition of soil, compost, organic matter, and mulch with a gradual transition zone without the cardboard layer, as is found in nature.

When you have your substrate mix prepared by combining raw cellulose mixes and soaking them then you can pour the water and two thirds of the substrate from the container onto the soil of the space where you are making the mother bed. If you are using cardboard in the bed, pour the strained water into the soil of the bed then put down the cardboard and then dump on two thirds of the soaked substrate and level and even it out. Open the bag of garden giant mycelium and break it up and scatter the pieces over the surface of the raw cellulose substrate. Press the pieces into the substrate to give the mycelium contact with the fresh food. Then you can add the rest of the substrate. When all of the bed of substrate is finished then smooth down the surface so it is flattened and the peaks are less likely to dry out. You can add a humidity later of tented burlap draped over staked poles inserted around the bed. Water the bed with a rain nozzle to settle it and then water periodically to keep the substrate damp.

If you would like to add an extra jump start to your mother bed then on top of the two thirds layer add a layer of soaked aspen shavings and mix the spawn into that layer and add the other third of substrate to the top of the aspen/spawn layer.

Periodically monitor the bed to observe the progress of the mycelium through the substrate. When it is fully infiltrated and making a bed of matted wood chips that can be lifted up as a layer then you have a successfully infiltrated mother bed that you can use to inoculate other areas. Next see below on the Mycelial Garden Blob Livestock Pet.

Worm Bin Style Ramping Up
You can also use discarded or recycled worm bins as another method to ramp up your garden giant spawn. Fill three worm bins to the rims with prepared and wetted substrate and mix in one third of the bag of garden giant spawn into each bin. Then stack the bins so that each bin’s bottom is in contact with the top of the substrate of the bin below. Set the stack of bins on a plank of plywood so it doesn’t sit directly on the ground and cover the whole stack with a black plastic garbage bag to keep it damp. Check it periodically until it has fully grown through each bin. When the mycelium is fully grown through the bins, they will grow into each other through the mesh bottoms of the bins. Each bin can be used as a fruiting box or can be used as a mother bin to inoculate one or more 4’ x 4’ mother bed sections of a larger garden bed.

If you don’t have any used worm bins you can substitute with stacked wood-slatted bushel baskets, wooden wine boxes, plastic milk crates, or tack hardware cloth or bird wire to the bottoms of open boxes made with 1” x 6” boards.

Fruiting the Garden Giant Mushroom
The Garden Giant can begin fruiting at any time after if has fully infiltrated the substrate or has gotten concentrated in certain areas. The best way to initiate fruiting is to water the mulch substrate regularly so it soaks up the water like a sponge. You water enough so the mulch soaks up but not so much that it drains through to the soil beneath. This usually involves several short watering, or foggings with a Foggit nozzle, per day for a few days, so not much water is being used, but it is to soak the mycelium impregnated mulch and not the soil below. Soon the garden giant mycelium will begin making what looks like velvety chocolate marbles on the surface of the mulch substrate in humid areas of the burlap cover or under vegetation cover. Keep the bed sprinkled regularly after the little mushrooms develop and once they reach big button size you can stop watering the mulch and only spray the burlap tent to keep the air humid. You can harvest them at any stage from big button to fully unfurled portobello. Lift the mushroom up out of the mulch, cut off the base to transplant to other areas of fresh mulch and cook the stems and tops any way you would buttons or portobellos. Usually, you will get so many mushrooms that you can’t eat them in one meal so you can slice and dice and freeze them in ziplocks in the amount you would use in a mushroom dish. Put the frozen block in the pan or soup pot so it thaws directly in the pan or pot as it is cooking. Garden Giants taste like “regular” mushrooms to most folks, but some consider them to have a flavor reminiscent of asparagus.

Maintaining Your Mycelial Garden Blob Livestock Pet
As you ramp up the mother beds into more mushroom beds and you have a fully myceliated mulch bed then you can fruit them any time after they are fully infiltrated. You can also maintain the mycelium in the beds by adding fresh raw cellulose substrate to the top of the garden mulch bed. The best way to do this is to add 1-3” of fresh soaked substrate to the whole bed and then use a spading fork to stab the mulch bed over the whole surface. Properly, you stab the surface to the depth of the spading fork’s tines and then twist the fork as you pull it out of the mulch bed. This opens up the mycelial mat in the mulch and allows the new substrate to fall down into the mycelially matted mulch to give it fresh food. Then smooth out the surface and water to settle. The broken mat of mycelium will leap up and invade the new substrate and heal over the mat within a week when it is vigorously growing. Perhaps the bed needs substrate refreshing every month or couple weeks or couple months, depending upon its vigor.

What you have now created is your own pet blob of livestock mycelium that can be maintained at quite a large size. We have done this in mulch beds as large as 10’x20’, 20x20’, and 5’x60’ simultaneously. These size beds are each big enough to produce armloads of mushrooms every couple weeks. What you have is a bed of substrate these sizes and 6” to 24” deep with a mycelially matted blob hovering in the substrate. The life force of the mycelium hovers at the level it best likes so if the mulch is drying out it sinks lower into the mulch and if the mulch is wetter or there has been rainy weather for several days the mycelium may actually come out of the mulch and carpet the surface of the mulch. It devours more substrate that you add to its dorsal surface, digests it, and poops off of its ventral surface the broken-down cellulose as compost that builds the soil below. This pet blob will continue to fruit off its dorsal surface and build your soil below as long as you provide regular feedings of the substrate to its dorsal surface.

“Pizza Garden” Growing for Mushrooms
Some folks like to grow a Pizza Garden with all the ingredients for pizza, including mushrooms, in one garden bed. For this garden you plant your vegetables “audience” style with the tallest plants in the back and the shortest in the front, in relation to the east to west movement of the sun in the daily sky. The rows go east west so the tallest are on the north side of the garden bed and the shortest on the south side. The order of planting for height would be tomatoes in the back, then a band of eggplant and peppers, then a band of basil, then a band of onions and garlic, and then chives and the creeping herbs like oregano and marjoram at the front. When the plants have been planted out in the spring they will all be relatively small and with space between them. You mulch the garden with Garden Giant substrate with spawn mixed in from one of your ramping beds or bins. As the plants grow you can continue to add substrate to the mulch bed while leaving some steppingstones scattered around for future access. When the plants have grown through each other there will be a vegetation humidity chamber that breaks the wind and holds the humidity. You can dig around from the back side under the tomatoes to get to the mushrooms or from the front amongst the garlic and onions to get to the mushrooms under the basil, peppers, and eggplant. These will be veggie pizzas unless you add snail ranched escargot to the mix.

Rejuvenating an Old Bed of Garden Giant Mushroom Mycelium
Occasionally, you may have to leave your garden unattended for a period. The plants and fungi can usually take care of themselves for quite a while, but they will tend to go feral and do things that may not be totally according to your plans as the garden manager symbiont. As the Garden Giant uses up most of its raw cellulose that is smaller, thinner, finer, and more quickly broken down it will be left with the larger chunks of wood chips or pockets of raw cellulose that didn’t get digested as fast. You can dig through the broken-down compost mulch and scrounge up the various patches and pieces of mycelium that you find. The Garden Giant has the fine unicellular fuzz of the regular mycelium but also makes ropey rootlike “rhizomorphs” that often look like tangled and branching kite strings. These are like multilane mycelial highways and have a better ability to withstand drying or other adversity than the unicellular fuzz. This makes it one of the fungi that can be recognized by its mycelium without mushrooms being present. However, the Stinky Whiffleball or Lattice Stinkhorn, Clathrus ruber, also makes these rhizomorphs so it is a mycelial lookalike to the Garden Giant.

You can add these Garden Giants rhizomorphs and mycelial pieces and undecayed patches to a new mother batch of damp aspen wood shavings in a plastic bag like you are using tinder to start a fire. As the mycelium grows you can observe its progress in the bag and then ramp it up by any of the other methods covered here already. Or you could rake up the old mulch bed and spread a layer of new mulch substrate over the whole bed and see what begins digesting it.

Addenda
The Anaerobic Sauerkraut Method of Sterilizing Substrate
If you would like to sterilize your substrate to give the mycelium less competition from other organisms it isn’t necessary to boil it or use hydrogen peroxide. You can soak the substrate in a 55-gallon drum of water (see below for info about chloramine in tap water) for 10 days to two or more weeks or for as long as you like, the smellier the better. After a couple days the oxygen in the water will be used up by aerobic organisms which will then drown or die of asphyxiation. Then anaerobic organisms will take over and use the substrate for their own different methods of metabolism. As long as the substrate is submerged in the anaerobic water by weighing it down with cinder blocks on a plank or some such, it will all look pretty much as fresh as the day you put it in the water. If you use only straw from a straw bale, it will remain tan colored very much like sauerkraut for weeks or months in submergence. When you are ready to use the substrate dump the barrel over and spread out the substrate so that it is exposed to the air and rinse it with water. The oxygen in the air will kill off the anaerobic organisms and now your substrate is sterile. The only expense is water and time, no expensive dangerous chemicals, or heat from propane.

Neutralizing Chloramine in Municipal Tap Water
It used to be that most municipal water supplies were treated with chlorine to kill pathogens. It would also kill any other organisms so that if you wanted to use tap water in your aquarium you had to fill the empty aquarium and let it stand for 24 hours so the chlorine evaporated before you put the fish in the water. Now the chlorine has been replaced with chloramine which doesn’t evaporate from the water. So, the aquarium water now has to be treated with a special neutralizer that comes in a dropper bottle available at the aquarium store. You can also neutralize it for free by using any garden clay that you bake in the oven to sterilize for a couple hours at 300 degrees. You can sift this powder and add a pinch to your glass of drinking water to neutralize the chloramine’s antibiological activity for your health.

You can also stir in about a tablespoon or two of this clay powder to a 55-gallon drum, or a bathtub, or a wheelbarrow of tap water for soaking substrate. The antibiological activity of the chloramine in the water is instantly deactivated or neutralized by the clay particles that bind to the chloramine. When watering your mushroom mulch bed, you can probably successfully remediate the sprinkling water by scattering a hand full of clay powder over the top of the mulch before watering. It is unclear how much effect the tap water may have in the garden, and it is also leached and neutralized by rain water falling on the garden.

Garden Giant Mushroom Images
For images of the garden giant mushroom you can do a google images for:
Garden Giant Mushroom
Stropharia rugoso-annulata
King Stropharia
Burgundy Mushroom
Wine Cap Mushroom