Straw Mushrooms: A Guide to Cultivation and Harvesting

The method of growing straw mushrooms is very simple, and taking care of them is not difficult at all. Fresh straw mushrooms are delicious, nutritious, easy to grow, quick to harvest, and there is a vast market for them. If the correct techniques for growing straw mushrooms are applied, they can be harvested quickly, yielding high economic returns.

Straw mushrooms are quite familiar to our people. These mushrooms typically grow on a common substrate, which is straw, hence the name straw mushroom (Volvariella volvacea).

For every ton of straw used to grow mushrooms, after deducting costs over a period of 15 to 20 days, you can profit between 500,000 to 700,000 VND. The waste after mushroom cultivation can be processed into high-quality organic fertilizer. Additionally, mushroom waste can be used to feed earthworms, which in turn can be used to feed poultry, livestock, and fish.

How to Grow Straw Mushrooms

Growing Season

Straw mushrooms can be cultivated year-round. During the Winter-Spring season, especially close to the Lunar New Year when cold winds prevail, it is necessary to block the wind, maintain warmth, and make larger mushroom beds. In the rainy season, a thicker roof or straw cover should be prepared to reduce humidity, and the beds should be raised to avoid flooding. In windy areas, strong winds require windbreaks, and the mushroom beds should be arranged perpendicular to the wind direction.

Site Preparation

Select a location that avoids direct sunlight to prevent adverse effects on the mushrooms; it should be cool and clean to avoid pathogens.

Straw can be placed in various locations such as around the house, in orchards, on tiled or concrete surfaces, or on shelves, in plastic bags, etc. The site must be flat and dry to prevent flooding during the rainy season, and being close to a water source is preferable for irrigation and care, making your straw mushroom cultivation more effective and quicker.

Materials for Growing Mushrooms

Various materials can be used to grow straw mushrooms, including straw, bagasse, banana stems and leaves, water hyacinth, and cotton. However, straw is commonly used. The straw can be fresh and green or dry, provided it is not rotten (which has turned brown to black), as this will result in lower yields.

Choosing the right mushroom spawn is also crucial, as the spawn will determine the success or failure of your home mushroom cultivation. The spawn should be free from diseases, not too old or too young, and have a pleasant aroma. The spawn bag should have a distinct smell of straw mushrooms, be free of spots, and the mycelium should cover the bottom of the bag.

Straw Fermentation Method

Method of fermenting straw into piles. This method can be applied to both fresh and dry straw. The steps are as follows:

The straw is stacked into piles, with a width of 1.5-2m and a length of 4-8m. When stacking, each layer of straw should be 20-30cm high, watered evenly, and compacted with feet. Continue stacking layers until the pile reaches a height of 1.3-1.5m. Then cover with plastic, dry straw, or banana leaves to retain moisture and heat. A few days after fermentation, the temperature in the pile rises to about 60-70°C, killing off wild mushroom spores and partly decomposing the organic matter in the straw, making it easier for the straw mushrooms to absorb nutrients and grow well later on.

Main material in straw mushroom cultivation is fermented straw

After fermenting for 10-12 days, the straw pile will settle down to about 0.8-1.0m high. At this stage, the straw can be taken out and arranged into beds.

How to treat lime water before fermentation. This method is applied to dry straw. The straw is dipped in lime water, mixed at a ratio of 3 kg of lime to 100 liters of water. The straw should be submerged just enough. The purpose is to kill off unwanted fungi and remove impurities in the straw.

The soaking time in lime water is from 20-30 minutes, after which it is taken out, drained, and stacked into a pile with a width of 1.5-2m and a length of 4-8m. Lightly compact it, and cover with plastic, straw, or banana leaves to retain moisture and heat.

Fermentation duration of 5-6 days: In the first few days, after stacking for 2-3 days, turn the straw once. If the straw is too wet, reduce the covering. If the straw is dry, additional lime water mixed at a ratio of 3 kg of lime to 100 liters of water should be added and watered just enough.

On days 5-6, check the straw pile again. The straw should be adequately moist; when squeezing a handful, a few drops of water should ooze out.

The straw must meet the following conditions for mushroom cultivation:

• The straw should be completely soft.
• It should have a bright yellow color.
• It should emit the characteristic aroma of fermented straw.

Selecting Mushroom Spawn

This stage is critical as it greatly affects the yield of mushroom cultivation. Choosing good quality spawn, at the right age, and free from contamination will result in high yields and good quality mushrooms.

Criteria for good spawn bags: The mycelium should be clear white, and when the bag is opened, it should smell similar to straw mushrooms. The mycelium should grow uniformly throughout the inside of the spawn bag. (For some spawn types, when the mycelium matures, it may cluster into reddish-brown grains but still produce good yields). A standard spawn bag weighs about 120g and can be sown on a mushroom bed that is 0.5m wide, 0.4-0.5m high, and 4-5m long.

Note when selecting spawn: Do not choose bags with brown, black, or orange spots, as they are contaminated with wild fungi. Do not select bags that are wet, mushy, or have a sour smell at the bottom.

Arranging Beds & Spreading Spawn

Taking straw from the fermented pile: Remove the outer layer of straw from the pile. Take the inner straw to arrange the mushroom beds, trying to complete this task within the same day.

Forming the mushroom bed

Method 1: Spread a layer of fermented straw over the bed surface, then water it. Use your hands to compact it so that it is about 50cm wide and 20cm high. Spread the spawn along both sides of the bed, about 5-7cm from the edge. Repeat this process for the second, third layers, etc. If three layers are made, do not spread spawn on the top layer; just cover with 4-5cm of dry straw. Water and compact it again, smoothing the surface of the bed. An uneven surface may damage small mushroom buds during harvest, reducing yield.

Regular watering is necessary to maintain moisture for mushroom growth and prevent pests

Method 2: The fermented straw is rolled into bundles with a diameter of 15-20cm and a length of 45-50cm, stacked neatly in layers. After each layer of straw, spread spawn along both sides of the bed, maintaining a distance of 5-7cm from the edge, and continue stacking as before for the second and third layers. If only three layers are made, cover the top with 4-5cm of dry straw, water, and compact it, smoothing the surface.

Note: Depending on the season, adjust the thickness of the covering accordingly. In sunny seasons, use a thin layer of straw to release heat. In rainy or cold seasons, use a thicker layer to retain heat and prevent water from seeping in.

How to Care for Straw Mushrooms

Caring for the mushroom bed

For straw mushrooms, there is no need to use additional fertilizers, as the decomposing straw provides sufficient nutrients for mushroom growth.

Monitoring temperature and humidity is the most crucial step in the production process. Humidity is a key factor, as it facilitates the decomposition of straw, which creates the temperature within the mushroom bed. If there is excess moisture, the temperature will drop, and the mushroom bed will become cold. If humidity is insufficient, the bed will dry out, leading to increased temperature.

Maintaining appropriate humidity: When checking the mushroom bed, take a handful (about 15-20 strands) of straw from the middle of the bed, squeeze it tightly in your palm; if water slightly oozes between your fingers, it is just right.

If no water oozes, it is too dry, and watering is necessary. If water drips between your fingers, it is over-watered, and you should stop watering and remove the covering to allow water to evaporate. During the rainy season, a roof should be built after removing the covering.

Adjusting temperature by watering and covering the bed: When checking the mushroom bed, if the temperature rises and the straw is dry, use a watering can to moisten the bed. Avoid using a strong water hose, as it may damage the mycelium and small mushrooms. If the temperature rises without a lack of water, reduce the wet covering and replace it with dry straw to reduce heat and allow ventilation.

If the temperature decreases and the bed becomes cold: Stop watering, remove some of the covering, and allow sunlight to reach the bed. If it is the rainy season, use plastic or agricultural film (with the black side facing up) to help the mushroom bed retain heat and increase internal temperature.

Straw Mushroom Cultivation: After incubating the substrate for 5-8 days, remove the straw cover, fluff it up, and cover it back for mushroom growth. It is necessary to turn the substrate to prevent the mycelium from spreading outside, which can hinder mushroom production.

Straw mushrooms are a short-term crop, quick to harvest

Harvesting Straw Mushrooms

After incubating the straw for 10-14 days, harvesting can begin: the timing of the harvest depends on the type of spawn and the incubation method. Mushrooms typically peak in growth on days 12-15; after that, a second flush occurs 7-8 days later, with harvesting taking place over 3-4 days, completing the mushroom cultivation cycle (25-30 days).

Harvest Timing: Harvest twice daily. The first time should be early in the morning, before 6 am. The second harvest should be around 2-3 pm.

Selecting Quality Mushrooms for Harvest: Straw mushrooms grow continuously, and many can become entangled. It is essential to select those that are still budding and slightly pointed at the tip. To harvest, gently twist the mushroom and pull it away from the substrate. Avoid leaving any mushroom stems behind, as decaying stems can spoil nearby buds. After harvesting, carefully cover the substrate again.

The harvest period typically lasts 7-10 days, yielding an average of 1.5 kg of fresh mushrooms per meter of mushroom bed.

Freshly harvested mushrooms should be consumed within 2-3 hours. If they need to be kept for the following day, store them at a temperature of 10-15°C.