5 Simple, Low-Tech Methods For Growing Edible Mushrooms Outdoors - a Step-By-Step Guide
- Fat Fox Mushrooms
- 7 days ago
- 13 min read
Growing your own food can be such a rewarding activity - not only do you get to try unusual varieties that you can't buy in the shop, but you also get to watch the entire process. Then when the time comes, you can harvest the fruits of your labour yourself and enjoy cooking with ingredients that are as fresh as they come! Growing edible mushrooms is a very different process to growing plants, but don't let that put you off. With the right methods it can be just as easy, if not more so. In our blog post, we outline 5 simple methods to grow mushrooms in your outdoor space.
Jump to section
Super low-effort method: bury a block of mushroom sawdust spawn
Looking for the lowest effort option that doesn't require much space? You can simply dig a hole in a suitably shady spot and bury the entire block of mushroom spawn and get results!
Though this method will yield less mushrooms that other methods, you'll get mushrooms more quickly and it's perfect if you don't have a lot of space. Don't have space in the ground or a raised bed to work with? No problem - you can even do this method in a large pot!
You will need:
A bag of mushroom sawdust spawn. This method will work for a range of species, but those that are naturally top fruiters are a good choice. We recommend blue oyster for beginners since it is a faster grower and tolerant of a range of conditions, but king oyster, king stropharia, or poplar fieldcap can also work well. If you're interested in growing medicinal mushrooms, reishi can also be grown this way.
Some brown cardboard
Some hardwood sawdust, fresh hardwood chips or chopped cereal straw (optional)
Method:
Choose your location: somewhere that is sheltered and stays in the shade works best
Dig a hole where the mushroom block is to be buried: dig a hole that is slightly larger than your block of mushroom spawn. You want it to be large enough to accommodate the block of spawn plus a little extra and it should be a bit deeper as well since you'll be covering the block with a layer of soil and mulch.. You can check the size by placing the bag of spawn in the hole.
Line the hole: use ripped up pieces of cardboard to line the hole. At this stage, you can also choose to add a little additional substrate if you have it (straw, wood chip, sawdust)
Bury your mushroom block: take the mushroom block out of its bag and place it within the hole. Fill the rest of the hole back in with the soil that you dug out and firm it in place. Cover the top of the block with around 5cm of soil.
Cover with additional mulch: Add another layer of organic material as a mulch to help with insulation/moisture retention. You can use wood chip, straw or leaf litter here. This is optional but recommended.
Water your buried mushroom spawn: keep your mushroom block watered, especially during dry spells or when the top looks dry.
Over time, the mycelium will spread throughout the additional growing medium. Once outdoor conditions become favourable, mushrooms will begin to fruit naturally. Depending on the planting time and conditions, they’ll be ready to harvest in 1 to 6 months.When mushrooms begin to sprout, keep them moist by gently watering with a sprinkle-head watering can or mister.
Growing mushrooms in your mulch on veg beds and paths
If you're already growing vegetables in beds or have pathways in your garden or allotment which have been mulched with organic material such as straw and wood chip, you can take advantage of this and grow edible mushrooms in this underutilised space!
The main consideration when growing mushrooms outdoors is that they grow best in a location which is relatively shaded and sheltered - they won't grow if conditions are too dry. If you're growing tall veg plants, they will naturally provide some shade to the spaces in-between which creates an ideal environment for mushrooms to grow.
In return, the substrate you'll be growing your mushrooms on will act as an insulating mulch layer which will help with moisture retention and temperature regulation. As the fungi break down the organic matter, nutrients are released in forms that can be absorbed by plants. This decomposition process also improves soil structure over time, increasing its ability to retain water and air. Additionally, the mycelium (the underground body of the fungus made up of "root-like" structures called hyphae) can help bind soil particles together, reducing erosion and supporting a thriving community of beneficial microbes. Altogether, growing mushrooms in mulch not only recycles organic material but also enhances soil fertility, resilience, and long-term health.
The best species to grow with this method are king stropharia AKA winecap mushrooms and blue oyster mushrooms. Both of these species are hardy and vigorous growers, which means that they are forgiving in an unsterile outdoors environment where they will have to outcompete molds and bacteria to grow successfully.
To start growing mushrooms in existing beds or mulched paths, you will need the following:
Mushroom spawn. As mentioned above, we recommend king stropharia or blue oyster. You can choose either grain spawn or sawdust spawn, but we suggest going with sawdust spawn since grains will be at risk of being eaten by critters when growing outdoors.
Substrate (organic materials that the mushroom mycelium will grow on and break down for energy). A mixture of straw and hardwood chips/hardwood sawdust work well and it's best to use fresh wood chips so that there is less chance of competition from other fungi that will have started to grow. We recommend using 2 times the weight of your sawdust spawn. You can sometimes source fresh woodchips for free from your local tree surgeon. In the case of straw, wheat, rye, oat or barley straw all work well and should be chopped down so that pieces are around 3 inches long for best results, or you can use straw pellets.
A large bucket or tub for soaking your substrate
Prepare the substrate: Place your chosen substrate in a large bucket, cover it with water, and let it soak for 12 hours to hydrate. After soaking, drain off all excess water thoroughly. The substrate should feel like a damp, squeezed-out sponge - moist but not dripping wet.
Break up the spawn: Without opening the bag, gently break up your king stropharia or oyster mushroom sawdust spawn until it has a loose, crumbly texture with no large clumps.
Layer the substrate and spawn:
Spread a 1-inch-deep layer of the hydrated substrate over the area where you want to grow mushrooms.
Sprinkle a thin, even layer of mushroom spawn over the top.
Add another 1-inch layer of substrate, followed by more spawn.
Continue alternating layers of substrate and spawn until you’ve used up the spawn or filled your growing area. When applying mulch around existing plants, keep the total depth no more than 4 inches. Be sure to leave a gap of at least 1-inch around the base of each plant.
Finish with a final layer of substrate to fully cover the spawn and protect it from drying out.
Water thoroughly: Water the mulch well after setting it up. Keep it consistently moist while the mycelium colonises (ie. growing into and breaking down) the substrate.
The great thing about doing this on established veg beds is that you can water your mulch at the same time as your plants!
Once your mushroom mulch has been set up, the fungus will need some time to colonise the substrate. Over several months, it will gather energy by breaking down the material. Then it's a waiting game - often environmental changes such as rainfall or a drop in temperature will be a trigger to the mycelium to fruit. With this method it can take anywhere between 6 months to a year to see your first flush of mushrooms.
Starting a dedicated mushroom bed
By applying the same principle as growing in woodchip-mulched areas, you can create a dedicated mushroom bed for a larger mushroom harvest.
A mushroom bed is a great way of using an area that is in deep shade which would not be suitable for growing vegetable crops. We recommend using one 1.8kg bag of sawdust spawn for an area of no more than 4x4 feet for best results. The aforementioned king stropharia and blue oyster work well for this method. You can also do this with other species such as king oyster but will have a better chance of success with double the amount of spawn since it is slower growing and will be more susceptible to contamination or competition from other fungi in outdoor conditions.
Use the same materials as outlined in the mulch growing method previously.
Choose a suitable area to start your bed: Make sure it's somewhere shaded and with good drainage - you don't want it in a waterlogged area.
Prepare the bed: Weed the area to prevent any interference from unwanted plants. Once you've weeded the area, you can place down some pieces of soaked cardboard as an initial weed suppressing layer before adding your layers of substrate and spawn. The cardboard will also act as a barrier against competition from bacteria and fungi in the soil whilst your mushroom mycelium grows.
Layer your substrate and spawn: As with the previous method, alternate layers of substrate and your spawn, but this time you can be more generous with the depth of the substrate layers at around 2 inches of each layer of substrate. You can choose to hydrate beforehand or water in to moisten after putting down each layer. Aim for 4 layers of substrate with 1/4 of your total amount of spawn between each layer. Break up the spawn inside of the bag it came in first so that it is crumbly and easy to sprinkle fairly evenly.
Finish with a final topping of mulch: Make sure you finish with a final layer of organic material (wood chip, straw, leaf litter, or a mixture) to help the bed retain moisture and protect it from the elements.
Protect from disturbance from animals: As a final step, you may want to add some protection from animals that may want to dig up your newly made mushroom bed and nibbling. Using physical barriers such as shade cloth and netting or using pruned bramble branches can help deters pests.
Maintaining Your Edible Mushroom Bed
Once established, a mushroom bed of this depth can produce harvests for up to 3 years.
Add new organic material (woodchips and straw) to the bed each year to feed the mycelium keep it productive. To do this, simply top it up with another 3-4 inch layer of material, give it a light mix and water in.
Hot tip: colonised material from an established mushroom bed can be used to start another bed. It'll likely take around 6 months for your bed to be at this stage, but you can check by digging down into the bed - lots of visible white threads of mycelium growing on the wood chip/straw means that it can be used just like the sawdust spawn in the original process.
Growing in straw bales
Oyster mushrooms grow readily on plain straw, making it an easy and accessible option if you have a spare straw bale. This method tends to produce mushrooms faster than growing on wood chips, as straw breaks down more quickly. However, because it’s depleted sooner, you'll typically get fewer flushes overall. If you're eager for a quicker harvest, straw is a great way to get started with mushroom cultivation. For this method, we recommend using blue oyster mushroom spawn.
Instead of a straw bale, you can also make your own 'straw tower' by using chicken wire fencing to hold the straw together. Take a length of chicken wire mesh fencing, form it into a circle and clip it together, then fill the centre with straw, making sure to pack it down so that there aren't large air gaps.
Soak the bale: hydrate the straw by soaking in clean water overnight and then draining thoroughly.
Inoculate with your oyster mushroom spawn: break up your mushroom spawn in the bag. Next, make some gaps into the bale (using a garden fork or spade can help here) and push some handfuls of spawn into the straw to distribute it throughout the entire bale.
Water your bale to keep it moist: make sure you regularly give the bale a light water - if it dries out, the mycelium won't be able to grow. After a couple of weeks, you should be able to see some white threads of mycelial growth in the straw.
Keep the bale cool and sheltered: store the bale somewhere shaded so that it doesn't dry out too quickly or get too hot for the mycelium to thrive. It's a good idea to keep it raised off the ground using wooden slats or bricks to provide airflow at the bottom and prevent moisture from pooling.
You should have your first flush of mushrooms within just a few weeks!
Grow mushrooms on logs
If you are able to get your hands on some freshly cut logs, you can use them to grow mushrooms. They will need to be hardwood logs which come from deciduous trees. Usual choices are oak, beech, birch, maple, or chestnut.
It is possible to use sawdust spawn to grow mushrooms on logs, but it's far more convenient to use wooden dowels which have been inoculated with mycelium since these are easy to insert into a log. You can take a look at Fat Fox Mushroom's full range of mushroom dowel spawn for growing mushrooms on logs here.
How to choose a suitable log:
For the best chance of success, the logs need to be used no more than 6 weeks after being cut. As more time passes other fungi in the environment will have a chance to grow and colonise the wood, competing for resources from the fungi that you intend to grow.
Choose undamaged logs that have been harvested from disease-free trees. Logs with large cracks, patches of discolouration in the cross section, and loose bark should be avoided.
Go for a log that is 50cm-100cm length, and 8cm - 25cm in diameter. Any larger and the logs will be difficult to handle.
How to inoculate your log with wooden plug/dowel spawn and aftercare
Drill holes into your log: you want the holes to be in staggered pattern and approximately 15cm apart all over the surface of the log. Make sure the holes are the correct depth and width for your dowels to fit.
Insert the dowels into your log: place the dowels into the drilled holes immediately after drilling. Use a mallet to tap them in so the tops sit just below the bark surface.
Seal with wax: once all the holes have been filled with dowels, seal them with the wax. This will help prevent moisture loss as well as protect them from bugs and animals that may want to get to the mycelium. We recommend using soy wax or rapeseed wax, both of which are non-toxic and biodegradable.
Keep it somewhere shaded and sheltered: you will need to keep your log somewhere shaded from sunlight and sheltered from strong winds at all times so that it doesn’t dry out. When conditions are warm and dry, thoroughly water logs for 5–10 minutes once or twice a week. To help retain moisture you can cover them with breathable fabric like burlap, horticultural fleece, or shade cloth.
Six to nine months after inoculation, you should notice white mycelium appearing at the ends of the log, which is a sign that the plug spawn has successfully begun colonising it. If no mycelium is visible after 12 months, it may have been outcompeted by wild fungi.
It can take anywhere between 12-24 months for your first flush of mushrooms to appear. Whilst this method is the slowest to start producing mushrooms, once your log is colonised, it can produce mushrooms for several years!
For more in-depth information, go to our full step-by-step guide on outdoor mushroom cultivation on logs which includes further tips.
Growing mushrooms outdoors - common questions
What time of year is best to grow mushrooms outdoors?
You can start growing mushrooms at any time of year, but it's best to wait for a couple of weeks after the last frost or a couple of weeks before the first frost so that the mycelium doesn't get frozen before it has time to establish itself.
How do I know that I'm harvesting the right mushrooms?
Whilst rare, there is a slim chance that another species of wild fungus has grown and produced mushrooms from your log or mushroom bed; after all you are providing ideal conditions for fungi to grow. The likelihood of this happening is very low because by inoculating your substrate with grain or sawdust spawn that is already colonised with mycelium, your chosen fungi already has a head start over any wild fungal spores in the environment. Once your chosen mushroom species colonises the substrate, its mycelium takes over the physical and nutritional space and produces enzymes and metabolites that can inhibit the growth of competitors. The two species that we recommend growing are strong and aggressive colonisers (especially blue oyster), which means they are particularly good at outcompeting other fungi that may be present in the environment.
Tat said, it's always a good idea to carefully check your mushrooms against the species that you have intended to grow. To do this, pick a few mushrooms at different stages of development (remember, handling any mushroom, even ones which are toxic to consume, is safe) Examine the shape and colour of the caps, the spacing and attachment of the gills underneath, and cut the mushrooms in half to observe the cross-section (note the colour and whether the stem is solid or hollow for example). If you have a good nose, smell can be a great identifying feature for mushrooms. You can also take a spore print by placing a cap on foil or paper under a glass for several hours since spore colour is a helpful clue. Do as many of these tests as you can - it's good practice to get familiar with all of the characteristics of the mushrooms you are growing.
The good thing about king stropharia and blue oyster mushrooms species which we recommend in this article is not only are they easy to grow, but they are are both distinctive and relatively easy to identify.
How do I know when to harvest my mushrooms?
The best time to harvest your mushrooms will depend on the species that you are cultivating. With oyster mushrooms, you should harvest just as the caps of the largest mushrooms in the cluster are starting to flatten out. When the edges of the caps have started to flip upwards and darken and/or wrinkle, the mushrooms will be fully mature and starting to go past their best. Harvest entire clusters of oyster mushrooms at once by firmly twisting and pulling. You may notice some small, immature pins attached to the cluster but don't worry, it's normal for some of the smallest pins to not reach full maturity.
With king stropharia mushrooms, you can choose to harvest them whilst they are still in the button stage (the caps are still tightly curled in like a little ball on top of the stem, similar in shape to the button mushrooms you can buy in a shop), or you can wait for them to mature until the caps have opened up. If harvesting when mature, try to time it so that they have not dropped their spores yet, as they will become tougher after sporating. You will be able to see if it has already started to drop it spores by a purpley-brown coloured dust on the white stem.
Comentarios