Grow your own mushrooms outdoors

Growing fungi at home can provide you with fresh mushrooms or other fruiting bodies, such as puffballs or brackets, to consume for their nutritional value or their health benefits. Growing native

A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since. fungi also make gardens more supportive for wildlife as they create food and habitats for other organisms.

Fungi fit into unused areas, such as in among the plants of a vegetable bed, effectively doubling the available growing space. Plus, fungi add an extra layer of intrigue and beauty to gardens, contributing new colours, textures and shapes, particularly in the colder months when plant displays fade.

Recycler fungi that rot down and feed on dead plant material can be propagated and grown at home to produce fruiting bodies like mushrooms.

There are three steps to the process of cultivating fungi. First, you add a starter culture of a fungus to a fresh batch of dead plant material. Then the fungus needs time and the right conditions to establish within the material as it feeds and expands its culture. Lastly, once the fungus receives the right environmental cues, it will start to form its fruiting bodies, which it makes to spread spores and reproduce.

Fungal starter cultures come in many forms, such as growing on

Transferring young plants from one container to a slightly larger one, where they will have more room to grow and fresh potting compost. This encourages continuous, healthy growth. grain or wooden dowels. If you purchase a liquid fungal culture and bag of sterilised grain you can create your own fungus starter culture by injecting the liquid fungus into the grain.

Methods for outdoor mushroom growing are being improved all the time as the popularity of home-growing is rising, so stay up to date and read around to increase your understanding. Be aware that the methods or species that works in other countries may not be suitable in the UK.

What can you grow mushrooms on?

Different fungi grow best on different materials, so research your chosen species to select suitable materials. Many species grow well on straw, others need wood of certain sizes, such as logs, chippings or sawdust. Many fungi that can be grown at home prefer hardwood over softwood, and some fungi can only grow on a narrow range of wood species. Other materials like spent coffee grains, bran or cardboard can also be incorporated into growing projects, each providing different ratios of carbon and nitrogen to fulfil the preferences of different fungi.

Mushroom growing project ideas

Grow bags – The easiest way to grow mushrooms at home is using a pre-prepared bag containing a fungal culture already established on straw or sawdust. Select native

A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since. UK or Western European strains that are suitable for outdoor growing. Improve the look of your growbags by cloaking it in more attractive materials like a hessian cloak, woven willow cage or a macrame hanger. Make your own growbags by adding a fungal starter culture to some pasteurised materials such as a mixture of straw or sawdust and bran in a sterile growbag (a plastic bag with a filter patch). To minimise the risk of contamination by other air-borne fungi or bacteria, work quickly in a clean environment with minimal air movement.

Fungi logs – These are fun to assemble, but sourcing the fresh logs can be difficult for most gardeners, especially in urban areas. Purchase native UK fungi dowels, drill

A miniature furrow typically 1–5cm deep, made with a stick, hoe or rake. It is used for planting seeds or bulbs, and ensures they are positioned at the correct depth and spacing. holes matching the width and depth of the dowels into the log so they are well-spaced out. Hammer the dowels into the holes until level with the bark

Bark is the outermost layer of woody plants (trees, shrubs and woody climbers). It is several cells thick and provides protection against physical damage, disease and environmental stresses. Bark comes in a wide variety of colours and patterns, and these can help gardeners when identifying plants. The fissures and crevices of bark on older plants also creates valuable habitat for many garden creatures as well as lichens and small plants. , melt beeswax over a camping stove and paint the molten wax over the holes to seal them against contamination. 

Mushroom mulch

Mulch is a layer of material, at least 5cm (2in) thick, applied to the soil surface in late autumn to late winter (Nov-Feb). It is used to provide frost protection, improve plant growth by adding nutrients or increasing organic matter content, reducing water loss from the soil, for decorative purposes and suppressing weeds. Examples include well-rotted garden compost and manure, chipped bark, gravel, grit and slate chippings. – Either create a dedicated mushroom bed or top-dress areas that would benefit from straw or woodchip mulch with fungal cultures mixed into the mulch. The easiest method is to buy in a large volume of UK native fungal starter material, spread it out in between two layers of fresh mulch material. To bulk up the volume of your fungal starter culture before adding it to the garden, drill air holes into a clean bucket or barrel then fill it with alternating layers of fresh mulch and fungal starter culture, ending on mulch at the top. Pasteurising the mulch first will reduce the competition by other fungi and microbes.

Integrated design ideas – combine different project types into the design of your garden to get the best benefits for your plants and wildlife. For example, use fungi logs to build a raised bed to grow plants in and incorporate fungal culture material into a mulch covering over the soil. For expert help, consult a sustainable fungi gardening advisor.

Choose a space that suits your growing project and install them during cooler months of the year. Give them plenty of time to develop and meanwhile make sure they don’t dry out to keep the fungi alive. For any pre-prepared kits, follow the manufacturer's instructions.

Maintenance and protection

Fungi need moisture and indirect light to grow well. Grow your mushrooms in sheltered and shaded places to protect them from drying out. However, fungi-infused materials retain moisture better than plain materials do, so larger designs can work even in exposed positions and will help preserve moisture there.

During dry weather, water projects with fresh water from a water butt or the mains supply. Stack logs into piles to preserve moisture. Tightly stacked piles lack room for mushrooms to grow, so either stack them in an open arrangement like a crib stack or rearrange them as they start to fruit. You can also move fungi logs into a garage or unheated greenhouse during winter to protect against hard frosts.

Producing mushrooms

Projects containing fungi of different species, strains and sizes will grow and produce mushrooms at different rates. Grow bags are the fastest growing, and a pre-prepared bag may flush with mushrooms within a few days once you initiate fruiting by cutting it open and moving it outdoors. Fungi growing from logs or mulch

Mulch is a layer of material, at least 5cm (2in) thick, applied to the soil surface in late autumn to late winter (Nov-Feb). It is used to provide frost protection, improve plant growth by adding nutrients or increasing organic matter content, reducing water loss from the soil, for decorative purposes and suppressing weeds. Examples include well-rotted garden compost and manure, chipped bark, gravel, grit and slate chippings. will produce mushrooms according to the seasonality of the fungus used, often the following spring or autumn after they are installed. To encourage faster growth, consider keeping logs inside black plastic bags to raise their humidity

The concentration of water vapour in the atmosphere. This affects the rate at which plants transpire (lose water from their leaf pores), which in turn affects how much water their roots absorb from the soil. If air humidity is low, plants transpire quickly and become at risk of wilting if water is lost from the leaves faster than it can be absorbed by the roots. Different plants require different levels of humidity to thrive. Many tropical houseplants need high humidity and are best grown in a steamy bathroom, misted regularly or placed on a saucer of damp pebbles. In a greenhouse, humidity can be raised in hot weather by damping down (wetting) the floor or overhead misting. .

Harvesting

As mushrooms start to bud

A bud is a small, undeveloped shoot that contains the potential for new growth. Buds are typically found on stems, where they can be apical (found at the tip) or axillary (found between leaf axils) and may develop into leaves, shoots or flowers. , mist them with water each morning and evening until they are large enough to harvest, then pick them by twisting them off at the base. Once a flush of mushrooms has finished, the fungus should fruit again, possibly several more times depending on its size and condition. If growing mushrooms to eat, check that the produce matches the species you were trying to grow, as wild fungi may appear instead that may not be edible.

After the fungus stops producing mushrooms, keep the residues in the garden to feed wildlife and slowly rot away into the soil. Spent growbag cultures can be added to compost

Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own. heaps or mulch so long as you have used a native

A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since. fungus.

Only fungi which are native

A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since. to the UK or Western Europe should be grown outdoors in the UK as the fungal cultures and spores can spread into natural landscapes.

A variety of edible native oyster mushroom species suitable for home-growing, such as the blue-grey (Pleurotus ostreatus), tarragon (P. euosmus), branched (P. cornucopiae) and summer oysters (P. pulmonarius). Further native edible species include dryad’s saddle (Cerioporus squamosus), shaggy inkcap (Coprinus comatus), poplar fieldcap (Cyclocybe aegerita) and chicken of the woods (Laetiporus sulphureus). Turkey tail (Trametes versicolor) is excellent for supporting garden wildlife.

The following suppliers stock native fungi and display the provenance of their strains on their website:

• Fat Fox Mushrooms
• Jurassic Coast Mushrooms (Save 10% when using code RHS10)
• Spore Supplies
• Gourmet Woodland Mushrooms
• Kingdom Liquid Cultures

Most fungal culture suppliers sell fungal strains that are sourced from outside the UK and bred to be high-yielding for commercial mushroom production. Such fungi are very competitive in nature and are prone to becoming invasive

Invasive plants are those that grow vigorously, spread rapidly and can out-compete other plants. Native, non-native and cultivated plants can all be invasive. . Gardens are not suitable environments to grow such strains, instead look for reliable local strains of native

A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since. fungi.

Invasive golden oyster mushrooms on grow bag (Pleurotus citrinopileatus)

Never grow the golden oyster (Pleurotus citrinopileatus) anywhere in UK, Europe or the USA as it is highly invasive. It dominates the fungi in the natural landscape it has escaped into, causing severe damage to the communities of wild, native fungi.

Commercial lions mane mushrooms (Hericium erinaceus)

There is no ethical way to grow lion’s mane aka bearded tooth (Hericium erinaceus) outdoors in the UK as it is legally protected from being picked or sold. This means any strains available to grow at home are non-native or illegally collected. Non-native lion’s mane puts native lion’s mane populations at risk of being displaced or going extinct by hybridisation.

Some common non-native mushrooms like shiitake (Lentinula edodes) and wine caps (Stropharia rugosoannulata) have been grown outdoors in the UK for some time and have also escaped cultivation but appear to be spreading less aggressively than the golden oyster. It is still not worth the risk to native fungi to propagate these species any further. To grow non-native mushrooms, grow them indoors, filter exiting air for spores or use sporeless strains, and kill the fungal culture by baking it before adding it to the garden or compost

Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own. heap.