How to Grow Mushrooms in a Greenhouse

8 November 2022 | Matt

Today we’ll be discussing thoroughly how to grow mushrooms inside greenhouses.

What is a mushroom and how do they grow?

A mushroom is a reproductive structure that is created by fungi. You can think of it like the fruit of the plant. The seeds of the mushroom are millions of microscopic sports that are present under the cap of the mushroom. These spores (seeds) are blown away by the wind to spread.

Mushrooms are one of the many types of fungi (molds, crusts, etc..). They are considered one of the more developed types due to them having a stalk and cap. What is the difference between fungi and plants? For one, fungi do not have chlorophyll, which is the green pigment that allows plants to produce sugar using the sun’s energy. Fungi also are different from plants as they absorb food from their surroundings.

Mushrooms, like a lot of plants, can be grown inside greenhouses. On the contrary to most plants, mushrooms do not need sunlight to grow. They grow better in cool and light deprived areas. So, if you have a dark free space in your greenhouse, why not use it to grow mushrooms?

Equipment You Need To Grow Mushrooms in Your Greenhouse

If you’re interested about growing mushrooms in your greenhouse, these are the equipment you will need:

A four-tier Greenhouse - This is a great way of controlling the environment for the mushrooms. In addition, it saves a lot of space and can be used indoors. Moreover, it can house a number of trays or blocks. A humidifier can be added as well. A big advantage of the 4-tier greenhouse, is that it can be automated, so you will save a lot of time and effort from spraying manually multiple times per day.
Humidifiers - You can have a humidifier installed inside your green house to control the level of humidity inside. If your humidifier does not have a fan, loosen the cover several times daily to allow fresh air inside. However, it would be better if your humidifier had a fan. Since the fan pushes moist and fresh air to the chamber. Ultrasonic humidifiers tend to show a noticeable vapor stream. Cool mist humidifiers and I don’t recommend them. Just remember to wash your humidifiers regularly to prevent impurities from growing and risking contamination.
Hygrometer - Using humidifiers can sometimes lead to too much moisture, which it is why vital to have a hygrometer. The hygrometer allows you to keep track of the humidity level inside of your greenhouse.
Filter Patch Bags - To be able to grow mushrooms, you’ll need some serious disinfection. You can prevent impurities getting into the sterilized substrate by using the filter patch bags. These patch bags allow you to manage high nutrient filled medium and to adjust the high output from exotic mushrooms. Filter patch bags can also endure steaming (atmospheric & sanitizing) to guarantee the essential degree of sterility is reached.
Grow Lights - Grow lights provide the specific light condition that your mushrooms require. Just make sure that it does not generate too much heat.
The condition of the greenhouse - Although mushrooms grow best in the dark, a small amount of light will not hurt them. So if you don’t have a dark/dim area in your green house, you can perform some modifications to block the light from a certain area. You can also make sure that the temperature in that area is in a range between 12 and 19 degrees Celsius. You can use a thermometer to monitor the temperature. Strong drafts inside the greenhouse can be fatal to mushrooms, so make sure you prevent strong drafts in that area.
Mushroom Logs/Trays - Trays and logs are two of the most common methods to grow mushrooms. Mushroom trays and usually 2 feet long and around 10 to 12 inches deep. These trays can be prefabricated or build from scrap wood. You fill the trays with a growing medium, then treat with mushroom spawn. If you’re looking to grow a small number of mushrooms, you should use the log instead. Logs are usually 4 to 6 inches in dimeter and around 40 inches long and are usually cut from an oak tree. To use the log to grow mushrooms, simply drill several holes in the log and fill the holes with mushroom spawn.

mushrooms growing on ground

Planting Mushrooms in Your Greenhouse, Step by Step

First, start by setting up trays inside your greenhouse. These trays should be around 8 inches deep and around 6 to 8 inches long.
Fill 6 out of 8 inches with peat moss, compost and mushroom spores.
Cover the trays with newspaper so it can maintain its moisture and prevent light from reaching it. Keep the newspaper on until whitish mycelium appears on the surface of the compost.
After the whitish mycelium appears, fill the remaining 2 inches with damp peat moss and then cover with newspaper again.
Leave it for two weeks, then remove the newspaper once you notice little whiteheads coming out of the compost.

Best Compost for Mushrooms

Unlike plants which grow in soil, mushrooms demand a different growing medium. Horse manure combined with straw offers an excellent medium for growing mushrooms as it is rich in nutrients and moistened. It is also possible to use compost that is made from straw, corn hay, water and peat moss.

If you are looking to grow a large number of mushrooms, then creating your own medium will not be effective. It is better to buy readily made mushroom kits that have a growing medium and mushroom spawn included.

Types of Mushrooms You Can Grow in a Greenhouse

These are some of the mushroom types grown in greenhouses:

Cordyceps mushrooms
Champignon mushrooms
Morel
Culinary mushrooms
Oyster mushrooms
Lion’s mane
Shiitake
Portobello
Wine cap mushroom
Reishi mushrooms
Chaga mushrooms

mushrooms harvested in basket

Preparing compost substrate:

First, you need to get about 45 pounds of well-rotted fertilizer per 100g of spawn. I’d recommend horse manure as a compost for mushrooms which is easily collected from stables. Start by preparing a composite pile in an open shelter or shield it by some sort of wrapping. A thick layer of polythene will do the trick and will ensure that your composite is worm free and free of invertebrates, which can consume your mushroom spawn. The compost will be clean as long as you apply the proper composting temperature ranges.

Make sure your compost is properly soaked. Then begin forking into the pile of compost and press down. Within a few hours, the temperature in the center will increase significantly. Continue to shift the heap every couple of days for two to three weeks by forking the external cooler compost into the middle and moistening it every time. You’ll know that your compost is ready when it shows a dark brown color and has a sugary smell.

Mushroom Spawn

Mushroom spawns come in various forms; they type you need will depends on the growing method you choose. The most common forms of mushroom spawn are flakes and bricks. To use bricks, break them into golf ball sized pieces and plant them 1~2 inches deep into your chosen growing medium and leave a space of 6 inches between each piece. For flakes spawn, mix it into the growing medium at a rate of 1quat/15 feet of growing space. Mycelium will start to show after a couple of weeks, which is the system used by mushrooms to receive nutrients from the medium.

Watering for Mushrooms

Mushrooms need a lot of water to grow, so make sure you water your mushroom trays from 5 to 7 inches every 2 days. However, make sure that the substrate is dump and not extremely wet. Also, you’ll need a good kind of water for your mushrooms. I don’t recommend using chlorine water at it is not suitable for mushrooms.

You should regularly water your mushrooms during cropping season. Most of the water is wasted throughout transpiration and evaporation. Mushrooms take the water towards their cells and it is restored after watering the casing sheet. The weight of the mushroom greatly depends on the uptake of water taken from casing and the fertilizer.

Lighting Conditions for mushrooms grown in greenhouses

Mushroom do not need any light to grow as they don’t get their nutrients and strength from the sun like most plants. Make sure the area used for growing mushrooms is as dark as possible and sheltered from sunlight. If light reaches growing mushrooms, they will grow brown caps and you do not want that!! However, when they are starting to form heads, they’ll require dim light. So, during that phase, a fluorescent lamp will do the trick if you can’t get indirect sunlight in that area.

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Caring for mushrooms

After planting the mushroom spawn by several weeks, the growing area will be covered by white mycelium. To increase growth in this phase, adjust the temperature of the greenhouse to around 12~18 degrees Celsius. Watering is very important in this phase to keep the spawn moist. You’ll need to water them twice per day for the optimum result. Once the mycelium fully forms, adjust the temperature to 18 degrees Celsius and cover the logs/trays with a very thin layer of damp newspaper. You’ll notice tiny mushroom heads appearing after a few weeks.

Harvesting Mushrooms

You can either harvest mushrooms when they are small (button stage) or wait until they grow to maturity. You’ll need a sharp knife for the harvesting process. Simple cut the stem of the mushroom at the base.

Critical phases in mushroom growing

Implementing the best fruiting condition is considered one of the most critical phases in mushroom growing. You’ll need to maintain a specific moisture, airflow and temperature or else your mushrooms will be dehydrated and won’t bear any fruit.

It can be really challenging to supply sufficient airflow as well as maintaining high humidity at the same time. There are various types of mushrooms and each of them have their own environmental demands, so customize your growing area accordingly.

Some kinds of mushrooms can’t develop in total darkness and might need some adjustments in your growing area to allow some indirect lighting.

Conclusion

We hope you enjoyed our article on how to grow mushrooms in a greenhouse.

If you have any questions, leave them in the comments, or email info@swgreenhouses.co.uk.