Edible mushrooms have been used as food and medicine throughout history. Today, mushrooms are coming back into the mainstream as people gain awareness of their health benefits, umami flavors and cultivation techniques. There is an increasing number of studies documenting the bioactive compounds in many species, including delicious culinary mushrooms. These compounds are being studied for their antioxidant, anti-inflammatory, and anticancer effects. Still, many mushroom species can be expensive or hard to find. Because of this, DIY mushroom cultivation is gaining popularity. Mushrooms can be grown inside or outside and the methods can be anywhere from simple to more involved. This is a general overview of how mushrooms grow and some ways to cultivate them.
Spores are to mushrooms what seeds are to plants, agents of reproduction. While seeds are multicellular and most can be seen with the naked eye, spores are microscopic and usually unicellular. At full maturity, mushrooms will release spores into the environment. The spores germinate to form hyphae (root-like filaments) which fuse together to make mycelium.
Mycelium makes up the vegetative bulk of the organism and lives in the soil or other growing medium. This decentralized network of hyphae branches out consuming nutrients while producing fruit (mushrooms) in order to create spores and reproduce. Picking a mushroom does not harm the mycelium just as picking a fruit does not harm the tree.
The majority of cultivated mushrooms are saprotrophs (decomposers). They obtain food by releasing enzymes which break down organic matter into simpler components. We have been able to mimic this process by providing organic material for them to consume.
Substrate is any growing material that provides nutrition, energy and moisture to the mycelium. Examples include grains, coconut coir, straw, and wood.
Spawn is a culture of mycelium that has grown through a sterilized substrate. It will hold the specific variety of mushroom mycelium until it is ready to be “planted” into another growing medium. Spawn is available in many forms and is kept refrigerated until use. Examples include grain spawn, grow kits and plug spawn.
Overview of growing mushrooms from spawn:
The grow space and grower must be clean to minimize microbial competition. The space should be out of direct sunlight. There are numerous ways to grow mushrooms from spawn but they all share three basic stages: inoculation, colonization, and fruiting.
Inoculation: This is the “planting” of the spawn into a sterilized or pasteurized substrate. This is done inside a clean container where the mushrooms will eventually grow from.
Colonization: This occurs during incubation, which is the period of time where the spawn grows through and consumes (colonizes) the substrate. The cultivator follows the environmental guidelines for the specific mushroom. Generally, low air flow and high humidity are required at around room temperature. High humidity can be achieved by misting or by using an enclosed container. It can take one to four weeks for the mycelium to fully colonize the substrate and be ready for fruiting. At this point the mycelium should appear white-ish throughout and smell good and earthy.
Fruiting: As long as the environment is acceptable most mushroom species will begin fruiting on their own when they are ready. However, there are several things a grower can do to support healthy fruiting. This usually includes providing a slight drop in temperature, increased airflow and brighter indirect light.
Mushroom Grow Kits: All in One
Grow kits are a straightforward option for mushroom cultivation. These are bags or blocks of fully colonized substrate that are ready to fruit. The first two stages (inoculation and colonization) have been done already. This is a good place to start to have the satisfaction of seeing mushrooms grow easily.
The supplier will provide specific instructions but generally the kit is placed inside with good airflow and the bag is cut or sliced open. The kit is misted everyday and the mushrooms will begin to grow out of the opening. Mushroom fruiting times vary. For example, oysters usually fruit after a few weeks, while reishi will slowly develop over a few months.
Ready to grow kits can be left closed and put in the refrigerator to keep them dormant for a month or sometimes longer depending on the company.
After the first flush (harvest of mushrooms), kits can usually produce a few more flushes before the substrate is spent. Let the block rest for a couple weeks, then start daily misting again. New growth typically appears around the edges of where old growth was cut off.
Once done, the old mushroom blocks make a fantastic amendment to compost. They add moisture and help the other organic materials break down faster. They can also be used as an amendment for turf to help improve the soil structure. For use in gardens, let them age outside for 6 months before applying.
There are many reputable companies for getting mushroom grow kits. Below are some examples.
https://sundreamsfarm.com/collections/mushroom-growing-kits
https://fatmoonmushrooms.com/pages/lions-mane-grow-kit-instructions
https://www.fieldforest.net/category/indoor-grow-kits
Overview of Growing from Logs with Spawn Plugs
Growers may also choose to get spawn plugs for logs if they want a longer term outdoor project. Besides the initial inoculation, caring for mushroom logs is pretty hands off – just make sure they don’t dry out and have some patience.
The grower drills holes in logs cut from healthy trees. The spawn plugs are placed into these holes and then they are sealed with wax to keep the spawn from getting contaminated or drying out. The inoculated logs can be leaned against a building or stacked in a shady spot that gets rainfall. Logs should be watered during hot/dry periods but overall, occasional deep waterings are better than frequent light waterings.
Fruiting time will vary but generally logs will produce their first mushrooms anywhere from six months to two years after inoculation and will continue to produce flushes in cycles for up to eight years.
There are also pre-inoculated logs available which may give quicker results as the “planting” of the spawn and some colonizing of the log has been done already.
Shiitakes are a popular and easy choice for log growing but any wood decay mushroom will work, such as turkey tail or lion’s mane.
Field and Forest has a helpful tree species/mushroom suitability chart as well as more detailed instructions: https://www.fieldforest.net/category/growing-mushrooms-on-logs
Harvesting, Cooking and Storing
When to harvest will depend on the species and your preference. Mushrooms can grow quickly once they emerge and there are often multiple stages present at once. For example, the most common mushrooms sold in the United States all come from the same species, Agaricus bisporus, harvested at different stages in their growth cycle and selectively bred for color. The white button mushroom and the crimini (baby bella) are the immature forms while portobello is the mature form of Agaricus bisporus.
To appreciate the complex flavors of a new mushroom, it is nice to try them alone first by dry cooking them. This means putting sliced mushrooms in a dry pan (no oil/butter) over medium heat and cooking the liquid off, turning occasionally. The water coming out of the mushrooms will stop them from sticking. Once they seem dryer, add butter/oil and cook until they brown and develop crispy edges. Oyster and lion’s mane mushrooms especially benefit from this technique as they hold a lot of water and this concentrates their succulent flavor.
Mushrooms should be stored in a paper bag in the fridge so they can breathe. This will greatly extend their shelf life compared to plastic or glass. The shelf life will vary by mushroom. For example, oysters last around a week, whereas shiitakes can last up to three weeks properly stored in the fridge. For longer term storage, mushrooms can also be dried and put into sealed containers in a cabinet or other dark cool place.
Sources:
Featured Photo: Chestnut Mushrooms (Pholiota adiposa) by Orv Lehman of Hawk Nest Farm
A Beginners Guide to Growing Mushrooms at Home – Utah State University Extension
A review of the therapeutic and biological effects of mushrooms – PMC – National Library of Medicine
Agaricus bisporus,Tom Volk’s Fungus of the Month -University of Wisconsin Plant Teaching Collection
Growing Mushrooms at Home – University of Florida Extension
Mushroom Gardening – Purdue University College of Agriculture
Mushrooms – The Nutrition Source – Harvard School of Public Health
Seven Stages of Cultivation – Cornell Small Farms Program
Shiitake Mushroom Production: Inoculating Logs with Spawn – Ohio State University Extension
Six Steps to Mushroom Farming – Penn State Extension
Spent Mushroom Substrate – Penn State Extension
What are Fungi? – Utah State University Herbarium
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Excellent article.
Interesting and helpful article!