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How to grow oyster mushrooms

There is no doubt oyster mushrooms are number one choice for new growers and small scale farmers. One that is marketable, potential even for small scale growers and has the possibility of being grown profitably on small scale farm. Once you learn how oyster mushrooms are grown, you can use those skills to foray all other areas of mycology and mushroom cultivation. Oster mushroom growers get to choose between a wide variety of different types of oysters.

Some are heat tolerant and can be grown in tropical areas. Some are cold tolerant and can be grown in more temperate climates. While some are resistant to high levels of C02 and can be grown in small grow rooms. Basically, no matter where you live and the conditions you are facing, there is likely a strain of oyster mushroom that will work for you.

Let’s get started!

Substrate preparation

There are several techniques to prepare the substrate for Oyster mushroom cultivation: sterilization, pasteurization, chemical treatment, immersion in hot water, soaking in hot water e.t.c.

The overall goal of substrate treatment

Straw softening and other structural changes;
Modification of plant materials so that nutrients are made available for mushroom growth and development;
Building up of appropriate biomass and a variety of microbial products( some of these can serve as nutrient sources for the mushroom);
Establishment of selectivity, i.e. the compost promotes the growth of the mushroom over competitor organisms;
Modification of compost structure so that it holds more water; and
Building up compost moisture content to serve as a water reservoir for the mushroom crop.

In DeKUT, we use the method of soaking in water. Wheat, rice, maize, beans, or other cereal straw is treated with hot water (60–70°C) for 10min to 1h. Water is heated in tanks by firewood; the excess water is drained off and discarded. After cooling, the substrate is spawned and bagged.

Oyster Mushrooms growth stages

Step 1: Materials

Raw materials for mushroom substrate:

Chia stalks, any kind of straw, banana leaf, dry grass (any), coffee husk/pulp and other agricultural residues.

Other materials:

Spawn
Firewood
Water
Plastic net sheet
Disinfectants

Equipment:

Straw cutter
Drum for hot water
Mixing bowl (big)
Buckets (20 liters)
Gloves

Step 2: Mix Straw and Bag

The mushrooms require a medium to grow in. In our case we will be using straw. The straw should be cut in small pieces with a straw cutter, approximately 5-10cm (2-4 inches). Placing the straw in drums with tight lids, submerge the straw in water for 24 hours for pasteurising. Rinse and drain thoroughly, then bag in buckets (20 litres).

Submerge in drum in water (boiled)

Step 3: Pasteurise

Put your drums on the heat source (we used firewood), pour around 40 litres of water into the drum. Heat the drum, the water should be (60-70 degrees) for 10 min to 1 h. Insert your bagged substrate into the drum and close with a tight lid. After 24hrs, the excess water is drained off and discarded. Leave to cool, by removing the bags and transferring them to incubation room.

Step 4: Prepare Incubation room

The incubation room should be dark or dimly lit. Plastic sheeting can be used to seal off an area to help retain humidity and reduce other unwanted moulds and insects. To prepare the room spray solution of bleach or peroxide along walls and corners (areas where mould might grow). Optimum spawn running temperatures in the substrate are 25-28c. Substrate temperatures below 20 c slow down mycelial growth and above 32 c can cause the mycelium to overheat. It is very important to monitor the temperatures in the middle of the blocks and not just the air temperature. Keep the room temperature in between 22-24 c.

Step 5: Inoculate buckets/bags

Before inoculating the bags make sure you have showered and wearing clean clothes. Clean and sanitize your hands with antibacterial soap or wear sterile gloves. A face mask will help reduce contamination.

Use a big bowl to mix your spawn and substrate evenly. As a general rule, the more spawn you add the faster your substrate will colonise (with 1 kilogram of spawn we inoculate 6 buckets – you can inoculate more).

Fill the substrate in the bucket and compress fully to reduce air circulation and close tighly with a lid. Incubation lasts 2-3 weeks depending on climatic conditions and spawning rate. S pawn running is carried out entirely in the dark to prevent the premature development of the fruit bodies.

Step 6: Monitor buckets/bags

It is important to monitor the bags for any sign of unwanted moulds and pests, while the substrate is in the buckets.The mycelium needs to colonize the substrate quickly in order to prevent the growth and development of competitor molds.The spawn run will be complete when the mycelium has spread entirely throughout the bucket (the straw is then fully colonised).
Once the substrate is completely colonized with mycelium, a sudden drop in temperature is usually required to initiate the so called “winter” strains.

Pleurotusostreatus (winter), 24°C (75°F) 2 to 3 weeks
Pleurotuspulmonarius (summer), 24°C to 30°C (75 to 85°F) 1 to 2weeks

Finally, as the bags become fully colonised, the initial stages of fruiting (or pinning) may be seen

Stage 7: Cropping

During this stage your mushrooms need12 hours of light per day with 100-50 lux on the surface is required after the incubation period for fruiting. The quantity of light can also influence the color of the mushrooms.During cropping, humidities of 80-90% should be maintained. Low moisture can lead to discoloration of the caps and some dying off. Misting/watering will prevent this but condensation on the pins should be avoided.

High levels of CO₂ during fruiting encourage larger stems and smaller caps. Levels of 500 ppm are ideal during spawn running. As the primordia are just beginning to develop in between each flush, the CO₂ can be increased to 1000-1500 ppm. Once the primordia start to develop, it is important to ventilate the room to prevent bacterial problems. To maintain good ventilation, 150 m²of air per tonne of the inoculated substrate at an air temperature of 12-15 C is suggested (high-temperature tolerating strains can grow on 20-25 C).

Stage 8: Harvesting

Remember to constantly monitor for pests, such as flies, as they can quickly ruin a crop.The first flush generally represents about 40% of total production. Growers usually harvest up to three flushes over an 8-10 week period. When harvesting, remove the mushroom completely, by twisting firmly at its base. If you find your mushrooms with long stalks and small caps, they may not be getting enough light, also high CO₂ levels can also lead to small deformities (allow for more fresh air). After the straw ceases to produce mushrooms, it can befed to livestock or composted.

Now, finally take your harvested mushrooms and have a mushroomful delicious day.

Growing Mushrooms from Old Mushroom Stem Butt

You can grow mushrooms from the stems of your harvested mushrooms.

Stem butts are the base of a stem, where the mushroom attaches to the ground; a good stem butt will have some substrate and mycelium still attached. When fresh they can grow mycelium onto a substrate that can be expanded and eventually turned into an outdoor patch and fruited.

The advantages of the stem butt method are that its cheap and easy technique to try at home. You don’t need access to expensive equipment and it’s not very time consuming or resource intensive.You can grow mushrooms from the stems of your harvested mushrooms.

There are several benefits to growing mushrooms in this way

Growing mushrooms from the stems is more sustainable it takes less time than growing them on straw and it also costs less.
Additionally, growing from stems gives you fresh mushrooms for longer periods of time
Stem tissue is the best substrate for growing mushrooms because it has ample water storage capacity
Also, there are few contaminants that affect stem tissue, which also makes it an ideal choice
Another benefit of growing mushrooms from stems is that it is easier to grow larger mushrooms

3 Basic Steps of growing stem butt mushrooms

1. Inoculation

The first step is inoculation. We added our stem butt mushroom grain spawn(think of it like seeds) to a suitable substrate (think of it like soil) which included:

Bean stock 50%
Rice straw 25%
Grass 25%

Grain spawn can be made at home like in our case with stem butt mushroom or bought pre-made. After sterilizing your substrate through soaking in water overnight and draining the water from the substrate, the spawn needs to be mixed thoroughly in order to get the most possible “inoculation points.”

2. Incubation(colonization) of mushroom substrate

Once the spawn is added to the substrate and compressed fully into the growing bag or bucket, it will start to expand and grow over, spreading out and devouring nutrients.

This process is known as “colonization”. After 2 weeks which is approximately 14 days the mycelium will have formed on the buckets or grow bags completely and it is said to be “fully colonized.”

3. Fruiting

Once the substrate is fully colonized, it will continue to get thicker until it’s fully consolidated. Eventually pin heads will start to form.

At this stage you move the grow buckets in the growing room where these pins will eventually turn into a fully formed mushroom “fruits” which if grown correctly you will one can harvest up to 4 flushes and enjoy.