A mushroom is the edible fruiting part of a mycelial colony. Edible mushrooms belong to a wide variety of botanical orders and families that have been a source of food and medicine for human beings since pre-history. The earliest records of culinary mushroom cultivation date back to 600 CE in China where Wood Ear mushrooms (Auricularia auricula) were first successfully inoculated in wooden logs. Many historians believe medicinal mushrooms to have been cultivated even earlier on sacks of grain during the Egyptian dynasties.
Types of Cultivation
Modern mushroom cultivation is usually done through the inoculation of a substrate (wood chips, logs, sawdust, grain hulls, etc.) though a form of pre-inoculated mushroom spawn. Mushroom spawn is typically available in two forms: garden spawn and dowels.
Garden Spawn/Fruiting Kits
Garden spawn kits are pre-packaged blocks, usually sawdust, that have been inoculated with the desired species and variety of mushroom. Most garden spawn will be white and fibrous, a sign that the mycelium is well established and ready to fruit. Often these block of mycelium can be encouraged to fruits straight away in your home allowing you to enjoy an initial flush of mushrooms before planting them outdoors. Garden spawn are the best option for planting in piles of fresh substrate like wood chips or straw.
Dowel spawn kits are pre-packaged bags on wooden dowels that have been inoculated with with the desired species and variety of mushroom. Most dowel spawn kits will appear white and splotchy, similar to mold, a sign that the dowel spawn is ready to be planted. Dowel spawn can be used the same way garden spawn is if the species of mushroom can grow in a loose substrate like wood chips or straw, but works best when inserted into freshly cut wooden logs or stumps. Dowel spawn kits are the only option to grow some species of mushrooms that will not fruit on loose substrates.
Types of Growth Medium
Unlike plants, mushrooms require more than just soil to grow and fruit; we call these environments growth mediums or substrates. The growth medium is the most important part of mushroom cultivation as the growth medium provides the mushrooms the specific nutrients and conditions it needs to thrive. There are numerous growth mediums used in indoor cultivation based in everything from potato dextrose to yeast extracts, but as this growing guide is specific to outdoor cultivation we will be covering the 4 common types of growth medium best suited for your garden or backyard. One thing to always keep in mind when using wood substrates is that it must be freshly produced or sterilized to reduce competition from native mushrooms which may otherwise be dominant in your area.
Woodchips are one of the easiest to obtain, and inoculate, growth mediums available. It should be noted however that not all woodchips are appropriate for the kind of mushrooms you are trying to cultivate. A hardwood/softwood mix from a local tree service is perfectly fine for Oyster mushrooms, as an example, but would be difficult for Shiitake mushrooms to establish in. Once you are sure you have the right kind of woodchips for the mushrooms you are planting it's very easy to mix the spawn with the chips, water, and let them grow.
Sawdust is a similar medium to woodchips in that it is a great substrate for wood loving mushroom varieties. Sawdust has a couple advantages over woodchips in that is usually cheaply obtained and of one kind of wood, making it easy to match your growth medium to your mushroom plans. The other advantage is that sawdust is easier for mycelium to establish in and is also suitable for indoor cultivation. Sawdust has a disadvantage for outdoor use in that it has a low water-holding capacity and once completely dry can be a challenge to rehydrate.
Horse manure is the most widely used manure for mushroom cultivation, specifically for Agaricus family mushrooms like Portobello that do not grow on wood substrates. Horse manure combined with straw is rotted down into what is commonly sold as "mushroom compost" and is an excellent growth medium for growing these kinds of culinary mushrooms. Most manure based mushroom beds are kept in a climate controlled environment, but can produce just fine in outdoor conditions if kept moist.
Logs and Stumps
Logs and stumps are potentially the best environments for cultivating mushrooms, but take the most care to get started and will only accept inoculated dowel spawn. Logs and stumps must be cut fresh, so before you begin you will need to have a plan about what to cut, where to store the logs after they are inoculated, and make sure all your tools are available before starting up the saw. To inoculate a stump or log drill holes into it with a bit slightly larger than the dowels and hammer them in with a rubber mallet. After the dowel plugs are installed wash the entry points with a melted wax to keep out unwanted spores from competing native fungus. Logs and stumps are best for more challenging mushrooms like Lion's Mane and Chicken of the Woods.
Types of Mushrooms
There are many types of edible and medicinal mushrooms available for home cultivation - so many that it would be impossible to cover all of them in this growing guide. Mushrooms can be cultivated indoors or outdoors and in this growing guide we will focus on outdoor cultivation specifically. Here we will discuss the growing requirements and conditions of the edible mushrooms that Raintree Nursery commonly carries. Some mushrooms are very widely adapted and easy to grow, being able to take advantage of a wealth of different growing mediums and conditions, while others are very specialized in how and where they will fruit and take some experience to reliably cultivate them in your home garden.
Oyster mushrooms are by far the easiest and most reliable mushrooms you can cultivate at home. Oyster mushrooms prefer hardwood sawdust or woodchips, but will grow on almost any ligno-cellulosic material. These include, but are not limited to: straw, corn cobs, sawdust, banana leaves, cotton seed hulls, newspaper, cardboard, and even toilet paper rolls. Due to it's ability to grow in the great majority of agricultural by-products Oyster mushrooms have become the go-to choice for novice mushroom cultivation hobbyists. Oyster mushrooms are tolerant of a wide range of moisture, but prefer 60-65% whenever possible. Dowel spawn in fresh cut logs has the advantage of preserved moisture in the logs themselves, but any Oyster mushroom patch watered once a week will perform just fine.
King Stropharia, also called Winecap and Garden Giant mushrooms, are another common go-to species for those just starting out in mushroom cultivation. Like Oyster, King Stropharia grows in a wide range of lignin rich substrates, most commonly straw and hardwood wood chips. King Stropharia mushrooms do best in a garden bed style of cultivation than they do in logs, spreading freely wherever their preferred food sources are plentiful and the area isn't too dry. King Stropharia tolerates a little more sunlight than most mushrooms, but your initial mushroom bed will do best if it's started in full shade conditions. King Stropharia classically fruits in the early spring and fall, making mushrooms that can literally be the size of a dinner plate before they are done growing!
Portobello belongs to the Agaricus family of mushrooms and prefers manure or mushroom compost over wood, though any nutrient rich compost substrate will do. Immature Portobello are also called Cremini or Button mushrooms and are the most commonly cultivated culinary mushroom in North America. Portobello mushrooms grow best in raised beds and containers, but can also work in a thick pile of composting material provided it is in the shade. A 50/50 mix of straw and horse manure is the best, but corn cobs or other decomposing high-nutrient waste can be substituted if you don't have access to horse manure. To prepare the substrate fill black plastic trash bags with your chosen mixture and allow them to compost for a minimum of 2 weeks in full sun. Deposit the fresh compost into your shaded bed of choice and inoculate with your garden spawn. Make sure your bed doesn't dry out and you should have mushrooms within 2-4 weeks!
Shiitake mushrooms are more specific than Oyster or Portobello mushrooms and firmly occupy the intermediate difficultly of mushroom cultivation. Shiitake grows almost exclusively in hardwood chips, sawdust, or logs. Traditionally shiitake is grown in oak logs, but maple, birch, poplar, aspen, and beech are also great selections. Despite being classified a softwood, Douglas Fir is also a good candidate for shiitake cultivation due to it's high lignin content. While you can grow shiitake in sawdust or chips, those growth mediums are easily exhausted within 2-3 flushes. When grown in logs via dowel spawn, and properly cared for, your mushroom logs can fruit as often as every 5 weeks for over 5 years! Logs should be cut fresh and optimally inoculated on the same day as shiitake is not as aggressive as species like Oyster and benefit from as little competition as possible.
Maitake, also known as Sheepshead or Hen of the Woods (not to be confused with Chicken of the Woods which is completely different), are widely appreciated for their culinary and medicinal value, but are much more difficult to cultivate at home. Maitake grows almost exclusively on oak wood and is slow to colonize, so the wood has to be fresh and protected against competing strains of mushrooms. If the wood needs sterilized a pressure cooker is best, but good results can also be obtained by either steaming or boiling the wood. Once cut, or sterilized, logs are inoculated and incubated indoors for 2-3 months. After the incubation period, "plant" them outdoors by partially burying logs in a shaded spot with lots of high-nutrient compost. Inoculation time is best done in March-April, and moved outdoors in June. Fall inoculation can be done as well, with incubation over the winter and the logs planted as soon as the ground thaws in the spring. First fruiting may occur as early as August of the planting year, but typically they won't fruit until years post inoculation. Often Maitake will need to be exposed to cold to "shock" it into fruiting. This can be done naturally via winter weather, or the logs can be submerged in ice water. Once they begin fruiting, the Maitake logs will continue to fruit every year for each inch of log diameter and sometimes even longer.
Lion's Mane mushrooms have a unique and fascinating shape, must like a frozen waterfall with its cascade of downward facing spines. Lion's Mane, like Maitake, is valued for it's culinary lobster like flavor and suggesting medicinal benefits - specifically it's potential to fight anxiety, depression, and dementia. Also like Maitake, Lion's Mane can be difficult to cultivate in your garden due to it's long incubation period, but unlike Maitake it can be cultivated on a wider array of hardwoods giving you some flexibility. Lion's Mane works best on oak and beech wood, but will do well on elm, poplar, and maple wood as well. In the case of Lion's Mane you may see an early flush at the 6 month point, but it may take up to 2 years for fruiting to really take off and it cannot be shocked into fruiting regularly. For larger mushrooms Lion's Mane requires the use of larger diameter wood and it is suggested to use fresh stumps (also called "totems") or logs that are at least 10" in diameter.
Chicken of the Woods
Chicken of the Woods is one of the most iconic and highly sought after mushrooms due to its large size and pleasant flavor. It is also one of the most difficult mushrooms to cultivate at home due to its tendency to get out competed by other mushrooms in the local environment. Don't let that discourage you though, if you get it right Chicken of the Woods will start fruiting within a year or two and keep going every summer until it runs out lignin! Like most mushrooms, Chicken of the Woods needs to be inoculated in hardwood logs similar to Lion's Mane. The logs need to be as fresh as possible or sterilized and cooled immediately before installing dowel spawn. Afterwards they should be allowed to incubate, and kept moist, between 60-70 degrees Fahrenheit for 2-3 months. Once incubation is complete the logs should be located in the shade and almost completely buried in thick, high-nutrient compost. Water as necessary to keep the area hydrated and with a little luck your logs will start bearing in a couple summers!
USDA Plant Hardiness Zone
Mushrooms are hardy to USDA zones 2-10, unless otherwise noted. This rating tells you the minimum winter temperature the plants typically survive when properly hardened off.
On our web site you will find a USDA Hardiness Maps which provides information on the average minimum winter temperature in your location, by zip code.
Where to Plant Your Mushrooms
Nearly all varieties of mushrooms are shade loving. Due to the moisture needs of most types of cultivated mushrooms full shade is essential to keeping the mycelium moist and happy. Some kinds of mushrooms, like King Stropharia and Boletus, are tolerant of some sunlight provided that it doesn't dehydrate their growing medium, while others like Chicken of the Woods will only reliably fruit in wet, full shade conditions.
The type of substrate used to grow your mushrooms is more important than the soil quality the mushroom beds are installed on. Some species, like Oyster, are very widely adapted and grow on many kinds of substrate, but others like Lion's Mane have a very small number of acceptable kinds of wood they will fruit on. Be careful to make sure when you inoculate your mushroom spawn that you are doing so with fresh recently processed growing medium. Older wood, straw, etc. may already be inoculated with local wild forms of fungus that will actively compete and may even kill your desired spawn.
Growing Mushrooms in Containers
Container growing is especially good for mushrooms due to the ease of controlling the environmental factors that go in producing healthy frequent flushes of high quality fruit. As usual with mushrooms the keys are using a preferred growing medium for the kind of mushroom you want to cultivate and making sure your mycelium get the kind of consistent moisture it needs to grow and thrive. When growing in containers you can also make use of the grain and agar based substrates available for commercial cultivation that we did not cover in this guide.
Watering Your Mushrooms
This is the most important and often the most difficult part of successfully growing plants. There are many factors, including the humidity, temperature, soil type, wind, and amount of direct sun that affect how much and how often water should be applied.
While mushrooms love water, and need it daily, the way water is applied to mushrooms is as important as how much and how often it is given. For best results we suggest daily spraying, or misting with a spray bottle if you are container gardening, to keep the substrate moist without over watering it. Like most plants, mushrooms need air to breath and over watering can delay or even kill your colony just as quickly as allowing things to dry out altogether.
In rainy climates, like the Pacific Northwest, outdoor mushroom cultivation is easier and requires less supplemental watering through most of the year, but your mushroom patch will still need daily watering through the summertime dry season to remain viable and productive. In drier areas permanent irrigation will be required and can be achieved through the use of drip irrigation sprayers. Drip irrigation, especially in a shaded area, is a cost effective and long lasting solution for plants that need frequent water support.