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Think like a Fungus: Using Observations of the Natural World and Evolution to Grow More Mushrooms

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When faced with the challenges of growing mushrooms, it can be helpful to look at natural habitat of the mushroom species to figure out what condition might be adversely effecting them. Simple observations of the natural world can be a powerful tool to understand what might be helpful in optimizing your growing parameters. Whether you are a professional grower or passionate hobbyist, it gives you a chance to geek out and really get down and know the élan vital of your mushrooms.

Let's use Pleurotis sp. Oyster mushrooms as an example:

  1. Almost all oyster mushrooms grow on logs, on or near to the the forest floor, with plenty of fresh air.
  2. Oysters often fruit after a precipitation event or a rapid change in temperature.
  3. They thrive in the low light conditions of the forest under normal diurnal light and temperature patterns.
  4. Oyster mushrooms grow all over the world, so as a genus they can live in a wide range of conditions but many have spectated to live in an narrow range of temperature and humidity conditions.
  5. Oysters often grow on logs that host other fungi, mostly hardwood trees, but not all.
  6. Like most fungi they don't live on cow paddies or other animal waste, just the humus and dead trees of the forest.
  7. Mushrooms are one of the ways fungi have evolved to spread their spores.

What can we learn from all this?

1) Oyster mushrooms need Carbon, Hydrogen, and Oxygen to sustain their life. In a mushroom log, these come in the form of cellulose, hemicellulose and a little bit of lignin. There is some protein and nitrogen present in the cells of a tree, but not a lot. Oysters don not need much fertilization to thrive and fruit. Adding fertilizers like nitrogen can help boost production but it is important to remember these are NOT plants. They respond best to small amounts of supplements in natural forms that they can break down like coffee grounds, grain or hair. In some situations fertilizers can be a detriment, because they attract and feed other fungi, bacteria, and insects.

2) On the forest floor, oyster mycelium can live happily and not be affected by a multitude of pathogens lurking in the soil. When mushroom mycelium is healthy, it can keep invaders at bay. Always take steps to insure mycelium can have a strong, fast run by observing optimal temperatures and humidity with plenty of fresh air. A fast run is your best defense against invading fungi or bacteria.

3) Mushrooms need fresh air, so you cannot shut them up in a room where they are breathing their own waste products (CO2) and expect them to do well. Mushrooms can fruit in a closed environment, but expect them to be small and thin.

Using plastic bags to grow mushrooms is an efficient, cost effective way to grow mushrooms. Really there is no other containment system besides logs that works better. Obviously, they aren't the ideal system as far as air exchange. The humidity tents included in our grow kits have plenty of air holes, and we suggest maintaining good ventilation in the room or area where the mushrooms are fruiting.

4) Like plant flowering, mushroom fruiting is actually a stress response. It is a last ditch effort to have genes survive in the form of spores under adverse conditions. Things that stress the mycelium enough to form fruits include: rapid change in temperature, an increase in moisture, a physical trauma (like dropping a log on the ground), or coming to the end of its food source (a bag or log full of mycelium).

The easiest way to induce fruiting is by imitating a natural rain event. Finding a happy medium for everyday growing with moisture and mushrooms can be a bit of a challenge. I recommend keeping the moisture low. After all, in nature you will have times when mycelium will survive during very low moisture conditions. When things are too wet it invites all kinds of invaders. Keeping the moisture and humidity low also allows for a big rain-like signal that will induce fruiting when you do add water. When you are ready for a flush get out the hose or, in the case of logs, soak in a bucket for 24 hours.

5) Mushrooms grow outside where there is plenty of light. They often stay on the shady side of the log or in a crevices. For fruiting it is necessary to expose mycelium to some light but keep it out of direct sunlight. They can take only small amounts of direct sunshine. If they are indoors in a room that has windows, use a light to mimic the natural day and night cycle.

6) Many people are surprised to find out things like mushrooms and bacteria can tell time. The fact is for the whole evolution of life on our planet there have been regular light and dark cycles. Given the Earth's volatile beginnings, it is pretty much the only environmental constant that early lifeforms could count on.

Oyster mushroom mycelium can be grown in the deep regions of a dark log so you can keep mushrooms in the dark during a spawn run. However, to initiate fruiting you will need normal light and dark cycles. If you are growing the mushrooms indoors without windows you will need a timer or manually turn lights on and off. Also, having the temperature lowered about 10°F at night will mimic normal temperature swings and get the mushrooms in the mood to fruit.

7) Blue and Pearl oysters are warm and cold weather varieties, respectively, but tend to be flexible with the range of temperatures in which they fruit. As with high CO2 levels, if oysters are grown outside optimal temperatures, expect flushes to be weaker and fruits to be smaller. Pictured here are Pearls and Blues that got too cold.

If a particular oyster strain doesn't do well for you in any given season, try another. The strain you are using might have evolved to a point where they can't be made happy with their environment. There is almost always a strain that will work for the temperatures, light, growing medium and humidity you can easily provide.

Many of our expert customers and farmers have developed a yearly cycle for what type of mushrooms they produce. Sometimes the spawn they order is exactly what you would expect- winter tree, pearl, and elm oyster for winter, pinks for summer, etc. Sometimes it is counter to what is read in many mushroom growing reference books. Many grow elms in the summer and blues in the winter. Mix it up and try a different strain or even species if you are having trouble growing in a particular season.

8) Oyster mushrooms grow fast and breakdown and eat the cellulose, hemicellulose, and a little bit of lignin. Other fungi, like woodear, are better at breaking down the fortified lignin walls allowing the fast-growing oysters to move in and enjoy the rest. So plant waste and materials made from plant cellulose that have little or no lignin (straw, paper, jute, agriculture wastes) are great for growing oyster.

When growing Oysters on logs, use young trees that have more light colored sapwood than the sturdy lignin fortified darker heartwood. “Softer hardwoods” like Maple, Poplar, Beech, Birch, Elm, work best for oysters.

9) Conifers contain resins that pine trees have evolved to fend off fungal and other invaders (think turpentine or cedar chips). Once these strong smelling compounds are gone fungi, like oysters, move in and have a feast on the nice soft pine wood.

Oysters that can grow on pine logs like Phoenix, only grow on less aromatic species like fir and hemlock. If you are using sawdust to grow oysters it is best to avoid all evergreens, especially cedar. Just a little bit of pine sawdust can inhibit oyster growth completely.

10) The myth that all mushrooms like to grow on horse pucky in basements is a notion we try to dispel here at EM. Almost all of the mushrooms we grow here live in the woods and grow on logs or from organic matter on the ground.

11) Like flower pollen and fruit seeds, mushrooms are a fungus's way of spreading their spores/genes around. Like seeds and pollen, mushrooms and spores can attract the animals and insects. Some mushrooms even glow in the dark to attract insects - like moths to a flame. If you are growing outside, anticipate that you might have some bug visitors. Take proactive measures to try to limit their access. Simple things like harvesting mushrooms as soon as they are ready will go a long way to keep a population from moving in and making a home.

Like many mushroom growers, my background is in plants. While a knowledge of growing plants is very helpful, fungi do grow very differently. If you are new to growing mushrooms take a moment to appreciate the time line of fungus growth. The mycelium run can take as long as a month in bags to several months on logs. Then fruits can appear suddenly. It takes some time to get accustomed to the idiosyncrasies of growing mushrooms. Much like growing plants, the more you appreciate, observe and understand the needs of the mushroom the better grower you will be. A green thumb can turn into a beige thumb in no time!