Stages of Mushroom Growth (& What Growers and Consumers Should Know)

Medicinal mushrooms are mysterious little creatures–neither plant nor animal, but so incredibly necessary and useful for our ecosystem. In the wild, mushrooms grow in complex, webbed patterns beneath the forest floor and sends signals to surrounding plants, helping them exchange nutrients and water. In captivity, mushrooms make for nutritious food and powerful medicinal supplements.

As unique as the mushroom kingdom is–so are the stages of mushroom growth. Whether you want to grow mushrooms on your own or just understand a bit more about these magical little creatures, you’ll want to understand the stages of a mushrooms' life cycle.

Here, we’ll break down everything you need to know about the mushroom life cycle and mushroom growth stages, from spore to the reproductive mushroom body, as well as how the growing cycles affects mushroom foods and supplements. 

Let’s get started:

When most people think “mushroom,” they think about the stem and cap portion of the fungi body, and they would be correct. A mushroom or toadstool refers to the fleshy, spore-bearing body of a fungus. The mushroom functions as the “fruiting body” of the larger organism–the fungus–which grows deeper beneath the surface in a tangled web of root-like, fibrous tissues. 

Many people relate the growth pattern of a mushroom to that of a plant since they often spring from the ground or from the sides of trees, but mushrooms and plants are much different. 

Mushrooms are heterotrophs, which means they rely on surrounding food sources for their nutrients, like decaying plant matter and animal waste. This is one thing that separates mushrooms from plants, which are autotrophic, meaning they can create their own food. 

Mushrooms have cell walls just like plants, but the composition is different. Plants have cell walls composed of cellulose. 

Mushrooms, on the other hand, have cell walls composed from glucan and chitin. Chitin is the material that makes up most insects’ exoskeleton, and is the material responsible for protecting the mushroom from predators and environmental harms. 

As you can see, mushrooms are unlike plants in many ways, taking some characteristics from the animal kingdom as well. But, they are neither plant nor animal, and they have their own unique mushroom life cycle that varies from any other plant or animal on earth. 

There are five basic mushroom growth stages in the mushroom life cycle:

1. Spore
2. Germ
3. Hyphae
4. Mycelium
5. Mushroom Fruiting Body

However, the process is a bit more in-depth than this five-step explanation. There are many sub-steps within these four steps that make up the entire mushroom life cycle. We’ll break it down below:

The first of the mushroom growth stages is the spore stage.

Every mushroom starts as a spore–a microscopic reproductive “seed” of sorts. These single-celled reproductive units are dualistic, existing as both the beginning and end of a mushroom’s life.

Mature mushrooms release spores into the air, which can be carried by the wind or water until they make contact with a suitable growing medium. Once a mature mushroom has released spored, it has fulfilled its purpose and will soon die.

Grower’s view: Because spores are microscopic, you cannot see them with the naked eye. They are usually sold attached to another medium, like paper or fabric, or they may be intermingled with a growing substrate. An advanced mushroom farmer may collect their own spores from mushrooms. 

The germ phase has nothing to do with germs–rather it refers to the germination of the spore into a “germ tube.” From the single-celled spore grows this first multi-cellular shoot of tissue. It grows via mitosis, a growth pattern in which cells split into two identical, same-sex cells. 

Grower’s view: As the germ tube grows, it may become visible to the naked eye, but you won’t usually see these among the growing medium. This growing phase is quick, so look out for hyphae soon. 

Next, the germ tube grows into a fully-formed hyphae. These are think, long strands of tissue that spread throughout the growing medium. 

Unlike the germ tube, the hyphae is capable of releasing digestive enzymes that break down food and turn it into an energy source. As the hyphae collect food and turn it to energy, they grow even longer and begin to intermingle with the surrounding hyphae that have sprouted from other spores. 

Growers view: Hyphae are thin white strands that are on their own or lightly mingled with other strands. You cannot always see these strands from the outside of the growing medium at first, but they will continue to expand and grow. 

As the hyphae intermingles, it begins a process called anastomosis. This is the most common form of gene exchange between fungi colonies. This allows the hyphae to form a larger colony of hyphae, which is known as the mycelium.  

Mycelium are essentially the “roots” of the mushroom, although they have more complex functionality than a plant’s roots. Just like the hyphae, the mycelium continues to grow and spread in search of energy sources. 

Mycelium grows beneath the surface, either in the soil or in the bark of trees or other broken down plant materials. The mycelium will work to consume all of the organic material available in its surrounding area. 

Mycelium can grow to be very large. In fact, the largest known organism on Earth today is a honey mushroom mycelium that covers 2.5 square miles. 

Growers view: Once this happens, you’ll see the thin white strands begin to form thick, white masses. The mycelium will work to consume and overtake the entirety of the growing medium. 

Finally, we come to the last of the mushroom growth stages: the mushroom fruiting body.

Eventually, the mycelium will encounter enviornmental conditions that will trigger reproduction. This varies by mushroom species but usually includes specific levels of carbon dioxide, light, temperature, or humidity.

Then, the mycelium will produce mushroom fruiting bodies, scientifically known as basidiocarps–usually a stem and cap with gills, that grows above the surface. Once the mushroom fruiting body matures, it releases spores to restart the growing cycle and immediately begins to decompose.

Growers view: As the mycelium begins to produce fruiting bodies, it will first produce “hyphal knots” which appear as small dots on the ends of longer stems. This is the primordium phase of the mushroom fruiting body, or the earliest stage of development. The process of hyphal knot creation is commonly called “pinning”. 

The mushroom life cycle is mostly the same for all types of mushroom species, but the growing medium and length of the life cycle may vary. There are two main types of fungi: 

• Saprophytes are a fungi that grow on decaying matter like dying trees or composted organic matter in the soil. Parasites need a living host, like a plant or insect, to support its growth cycle. 
• Parasites infect living hosts, such as plants or insects.

Before the mushroom life cycle  can begin, mushroom spores must locate a good growing medium. Spores are carried by wind, water, and animals and, if lucky, will land in a medium suitable for it's growth. The best growing medium for each mushroom life cycle varies by mushroom type. 

Mushrooms that are classified as saprophytes, like portobello, lion’s mane, or tremella, may grow on the side of trees or from the ground. In a controlled environment, you may choose to grow them from sawdust or wood chips (good for shiitake or lion’s mane), composted manure (good for white button mushrooms), hay or straw (good for oyster mushrooms), or another medium, like grain blocks or coffee grounds.

Parasitic mushrooms, like the cordyceps mushroom, actually grow from a living organism. One particular species of cordyceps, known as Cordyceps Sinenses, grow from a specific species of caterpillars native to some mountainous areas with cool climates. These mushrooms are hard to reproduce, so new species (Cordyceps Militaris) have been created to make them easier to grow in a lab or farm setting.

The life cycle length of a mushroom varies by species. Some grow quickly, in as little a 3-4 weeks. Oyster mushrooms are a good example of a fast-growing mushroom. 

Others, like shiitakes, can take much longer, from several months to a year, to produce fruiting bodies. Some fungi, like exotic truffles, can take ten years or more to turn from spores to fruiting bodies.

You’ll need to research the specific mushroom you want to grow to find a more specific measure of its growing cycle.

When mushrooms are grown as a food source, usually the fruiting bodies are harested to be eaten. However, when the end product is a mushroom supplement, some manufacturers may use the mycelium portion of the mushroom body instead or in addition to the fruiting body. 

These products will be called “mycelial” supplements or may be referred to as “whole mushroom supplements.” Unfortunately, this isn’t the best way to go when trying to reap the benefits of a mushrooms bioactive compounds (the betaglucans and terpenoids). 

When products are made from the mushroom mycelium, the entire block of growing substrate (usually rice, oats, or another grain) is thrown into the blender and ground up with the mycelium. That means that the end result is incredibly degraded and contains lots of grains. 

Dilution aside, the mycelium already contains a much smaller concentration of beta glucans than the fruiting body. The mycelum is estimated to contain around 5% beta-glucans, while the fruiting body can contain 20% or more. 

Still, manufacturers continue to uses this trick to produce mushroom supplements because it’s cheaper. Since the product contains some mushroom material, it can be marketed as a mushroom product, and the label can be misleading to consumers. 

Understanding the stages of mushroom growth is imperative for anyone looking to grow or forage mushrooms, but it’s also just a helpful piece of information for anyone interested in functional fungi or learning more about how mushroom colonies support our ecosystems. 

To sum it up, mushrooms grow in 5 stages:

1. Spores are released from fruiting bodies. They disperse and begin to grow when they find suitable substrate and environmental conditions. 
2. Spores germinate into a germ tube, a long thread like structure. 
3. Germ tubes become hyphae, string-like structures that can excrete enzymes to break down food and turn it into an energy source. 
4. Hyphae mingle and then join together to form mycelium. The mycelium continues to eat and grow until proper environmental conditions are met. 
5. The mycelium begins to grow a fruiting body–the mushroom–which eventually releases spores to restart the cycle.