Top of The Crops - Mushroom

Growing Mushrooms in a Polytunnel

Mushrooms are the fruiting bodies of fungi. These are healthy dietary additions and though foraging for these in the natural environment is something we should do only when absolutely certain of identification, anyone can grow 'safe' edible mushrooms at home. 

Fungi are amazing. We rely on them and work with them in so many diverse ways. They form key conduits in the wood-wide web, tie ecosystems together in complex communication networks, are crucial components in the soil ecosystem upon which we depend, play vital roles in decomposition, and even make us who we are, forming a part of the complex ecosystem of the human body. 

Of course, only a relatively small number of the many mushrooms and fungal communities out there are edible to us. But from that number we can easily find one or more that we can grow at home as an addition to our home-grown diets. 

The Preferred Conditions for Mushrooms

If you are interested in growing mushrooms at home then you will, of course, need to consider what the fungi needs to grow successfully. Different mushrooms will form and thrive in different settings, and it is important to understand the basic needs and preferred conditions of those you would like to grow. 

Usually, the things that we need to think about when determining what specific mushrooms need are temperature, light levels, and moisture levels. 

Most mushrooms typically grown at home will need moderately cool temperatures, dark/ shaded conditions, and plenty of moisture, though needs will vary depending on which mushrooms you have chosen to grow. 

Mushrooms will also require a suitable substrate, or growing medium through which the fungal mycelium can spread before the fruiting bodies that we refer to as mushrooms appear. 

How to Grow Mushrooms

The key to growing mushrooms successfully is understanding their needs and meeting those needs as closely as possible. For this reason, it is usually easier to grow mushrooms indoors or under cover in a more controlled and controllable environment. 

That said, it is also possible to grow mushrooms outdoors successfully as long as the basic needs of that particular mushroom variety have been met. 

One easy way to get started growing mushrooms is to purchase a mushroom growing kit. There are many such kits on the market that are readily available for home growers who wish to get started on a small scale. 

You can also purchase mushroom spawn and take a DIY approach. This may sometimes come with instructions as to the desired growing medium, conditions required etc... but you will often need to make more decisions on you own if you take this route. 

You may also purchase wooden dowels or plugs that have been inoculated with mushroom spawn to place into holes that you drill into freshly cut logs of a suitable type for the species in question. Or even simply purchase pre-made mushroom logs to place in a suitable location. 

Where to Grow Mushrooms

Where you will grow mushrooms will largely depend on the specific species that you wish to grow, and of course on the method for growth that you have chosen. 

You may grow mushrooms:

  • In a raised bed or box filled with a suitable organic-matter-rich growing medium in a shade polytunnel, shed, garage or other undercover area. 

  • In mulch materials or soil in a garden growing area. 

  • On a suitable substrate on a small scale inside your home. 

  • On logs either outside or in an undercover growing area. 

Growing Mushrooms in Beds or Boxes

If you are growing mushrooms in raised beds or boxes then of course the primary concern is to choose a suitable growing medium to fill those beds or boxes. 

One traditional option commonly used is a well-composted horse manure. But many other composts, and other growing media such as leaf mould or straw/bracken based substrates, can also often be used and can work well for certain species. 

It is important to make sure that the growing medium is suited to the specific mushrooms that you have chosen to grow and that it is sufficiently moist. 

The mushroom spawn will typically be spread across the surface of the growing medium and mixed in to around 5cm depth. It should then be covered with damp newspaper or a mulch. 

After several weeks, white strands of mycelium should be visible throughout the substrate. Once this occurs, the damp newspaper is removed and a half and half mix of soil/ compost and lime is traditionally added as a 2-3cm thick layer on top. 

With regular watering, mushrooms should begin to appear through this layer after a few weeks. Several flushes of fruiting bodies should occur through the growing season. 

Inoculating Mushrooms in Your Garden

Another option is to inoculate a specific area in your garden with mushroom spores. You might lift an area of turf and spread mushroom spawn below it before firming it back into place. 

Or you might inoculate a mulch with a specific type of fungi before spreading this mulch around a specific part of your garden – below a fruit tree, or in a shady spot, for example. Some mushrooms grow well in a wood chip mulch in a woodland or forest type environment, for example. 

Of course, when looking to grow mushrooms outside you will have a less controlled environment and this can make it more difficult to grow mushrooms successfully. Things can be less predictable and you also need to look out for interloping fungi and ensure that any mushrooms you eat have been identified with 100% certainty. 

Growing Mushrooms Indoors

Growing mushrooms indoors means that you will have a lot more control over the environmental conditions and can be more confident that no other fungi are present and that any mushrooms that form are of the expected variety and are edible and safe. 

Oyster mushrooms are an easy variety and are commonly grown indoors on a small scale. They are often the mushrooms grown with mushroom growing kits. Button mushrooms can also be a popular choice, though there are also a number of other options to consider if you take this route. 

Growing Mushrooms on a Log

Last but not least, you can grow a range of different mushrooms on logs. You can as mentioned above purchase logs that have been inoculated already with mushroom spores, or you can purchase plugs or dowels that have been inoculated to place into logs of your own, or you can purchase the spawn and take a DIY approach. 

It is important to understand which logs will work for the variety of mushroom that you wish to grow. Typically, hardwood logs will be required and these must be freshly cut to avoid the potential that other fungi are already present within it. 

These logs can be incorporated into garden landscaping – used to create supporting walls, bed edging or terracing perhaps, in a suitably damp and shady spot. 

They can also be incorporated into a dedicated mushroom bed, or simply stacked somewhere – behind a garden shed or in a darker corner of your space, for example. 

Health Benefits of Mushrooms

While different mushrooms have different health benefits, there are a number of mushrooms considered to provide health benefits when included within a person's diet. 

Mushrooms are a nutritious meat-free food source, a source of vitamin D, B vitamins and selenium that support a healthy immune system, and more. They are low in sodium, low in cholesterol and they are prebiotics, which are good for gut health. 

Varieties of Mushrooms

  • Oyster mushrooms, Pleurotus ostreatus etc..

Oyster mushrooms are generally considered to be among the easiest mushrooms to grow. They are commonly cultivated indoors or under cover and are frequently the mushrooms cultivated in simple mushroom kits. There are a number of different oyster mushrooms in the Pleurotus genus that you might consider growing in your home, in a polytunnel, shed or other undercover growing area. 

  • White button mushrooms, chestnut mushrooms etc., Agaricus bisporus

Agaricus bisporus are also among the most common and easiest mushrooms to grow, whether you are using a kit or taking a more DIY approach. There are two main types, which have either white tops, or brown ones. Both can be easily grown at home and are readily available to purchase here in the UK. These mushrooms can be grown in a range of different ways. 

  • Shiitake mushrooms, Lentinula edodes

A popular gourmet mushroom variety to grow, shiitake mushrooms are prized for their meaty texture and strong, rich umami flavour. They are also prized for their medicinal properties. These are often grown in windowsill kits, and can also be grown on logs or in a number of different substrates with some success. 

  • Lion's mane mushrooms, Hericium erinaceus

Delicious when eaten in a range of different recipes, and when cooked in different ways, these mushrooms are also prized for their medicinal properties. These have been cultivated as an edible crop in China and Japan for centuries but have also increasingly become popular in the west. These can be grown in the garden and are often grown on mushroom logs. 

  • Wine cap mushrooms, Stropharia rugosoannulata

Wine cap mushrooms are easy to identify and can work well as a mushroom to cultivate in a wood chip mulch in a shady section of a forest garden or other edible planting scheme. 

Common Problems for Mushrooms

Many of the problems that arise when trying to grow mushrooms involve issues with the environmental conditions. While mushroom will occasionally be eaten before you can get to them, pests are not usually as much of an issue as environmental conditions not being quite right. 

When growing indoors, for example, temperatures may be too high or too low for the mushrooms to appear. Moisture can also be an issue – especially if the growing medium or substrate dries out or humidity drops too low. Too much light can cause wrinkling and cracking of the mushrooms, while too little can cause paleness and long, thin stems... CO2 levels being too high can also be an issue in a closed space – so good airflow/ ventilation is essential. 

Top Tips for Growing Mushrooms in a Polytunnel 

If you wish to grow mushrooms in a polytunnel, the most important thing to remember is that you will need to choose the right cover – one that provides shaded conditions and will not let too much light through or cause the area to overheat. 

Remember, ensuring the right environmental conditions is essential in order to obtain a good yield. 

It may also be possible to grow mushrooms in a shaded area below polytunnel staging, to make the most of every inch of space...


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Inspired Taste. (2020) No-Fail Method for How to Cook Mushrooms. [online] Available at: [accessed 25/01/24]

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growing mushrooms in a polytunnel