Outdoor Mushroom Bed Instructions
For all outdoor sawdust spawn kits
This method of growing mushrooms outdoors will work for our blue oyster, phoenix oyster and poplar fieldcap sawdust spawn kits. All of the outdoor kits use UK-native strains isolated from wild fruiting bodies.
Each species of mushroom is a different growing experience. Even if you have grown mushrooms before, please read the instructions for your kit carefully before proceeding. If you run into any problems please see our FAQ.
Step 1: Finding an Ideal Location
Mushrooms grow best outdoors in moist, but not waterlogged, soil that is out of direct sunlight and shielded from the wind.
When growing mushroom outdoors, you have the choice of creating a bed in a designated area of the ground, using an existing raised bed cleared of weeds, or setting up a large planter that can accomodate the sawdust spawn an the additional substrate you'll be adding.
If you'll be using a container, it's important that it has drainage holes so that the substrate doesn't become waterlogged, which will suffocate the mycelium!
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Find a spot in your garden/allotment or place your planter in a place that is shady and sheltered.
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If you cannot find a spot with enough shade, you may use a tarp to act as a sun and wind shield.
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It's worth bearing in mind that other creatures enjoy mushrooms as much as you do. Slugs can be a particular problem when the weather is very wet. If this is a problem in your garden or allotment, we recommend using organic, non-toxic means such as copper tape, sheep wool pellets or barrier methods to protect your mushrooms.
Step 2: Preparing Your Additional Growing Medium (Substrate)
In nature, fungi break down organic matter such as dead trees and leaves. We can imitate this process by using commonly found organic materials such as sawdust, straw and cardboard as additional growing medium (substrate) to increase the yield of your kit.
Choosing your additional substrate:
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Sawdust and wood chips: this must come from hardwood trees. Softwood from coniferous trees is tougher for fungi to break down, one of the reasons being it contains compounds that inhibit fungal growth. Phoenix oyster is an exception in that it can feed on coniferous wood, but it will still perform better on hardwood such as oak, beech, birch, sycamore etc.
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Straw: oyster mushrooms in particular do very well on straw. The large surface area means that your cultivated fungi can spread into it quickly. Clean, untreated straw such as that sold for animal bedding is ideal.
It's important to use straw rather than hay - hay comes from cut grass with the leaves and sometimes seed heads still attached, meaning it is much higher in nitrogen and can attract competing growth from moulds and bacteria.
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Cardboard: this should be plain brown cardboard that isn't coloured and coated in anything that makes it shiny.
Planning to plant in winter?
It’s best not to plant your mycelium when the ground is frozen, as the spawn won’t establish well. In winter, mycelium will grow more slowly or go dormant due to the cold. Therefore, if planting during cold seasons, we recommend not breaking up the spawn. Instead, bury the whole block in a hole lined with cardboard, add moist straw or wood chips on top, then cover with soil. This method means you’ll get mushrooms faster, but you’ll get fewer mushrooms overall. You can try boosting yields later by adding more material once the weather warms up (see “Initiating The Next Flush” step at the bottom of the page).
Otherwise, for setting up a larger mushroom patch, follow the steps below to prepare your additional substrate for planting:
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Use ripped up cardboard, straw and/or sawdust and fresh hardwood chips as additional substrate for the mycelium to consume. You can use up to 2 times the weight of your mycelium block (1.8kg) in additional organic materials.
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The cardboard box and the brown tape used to package your kit are completely biodegradable, so that's usually a good place to start!
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Gather your additional substrate in a large bucket. Cover with water and leave to soak for no more than 12 hours. Drain off any excess water.
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You will also need to collect some pieces of plain brown cardboard to line the hole in the ground.
Step 3: Planting The Mycelium
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Dig a hole in your chosen location big enough to accommodate your mycelium block and additional substrate.
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Wash or sanitise your hands.
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Line the hole with sheets of brown cardboard.
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Thoroughly break up your mycelium block inside the bag so that it will be easy to sprinkle evenly with no large lumps.
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Now it's time to fill the hole with layers of substrate and the broken-up mushroom spawn. Build it up with a lasagna by alternating layers of substrate and your spawn, aiming for around 1-2 inches for each layer of substrate and a thin, even layer of mushroom spawn over the top of each substrate layer.
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Once filled to the top, cover over your hole with a 5cm layer of soil. You can optionally apply a thin layer of mulch.
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Generously water your new mushroom patch.
For more outdoor growing methods, check out our guide to growing mushrooms outdoors.
Important: You cannot mix sawdust spawn of different species together in the same bed, as different species will compete with each other. Make sure to use blocks of the same species.
Step 4: Maintenance
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Thoroughly water your mushroom patch during dry spells or when the soil looks dry.
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Over time the mycelium will colonise the additional substrate, and when outside conditions become favourable mushrooms will begin to grow.
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Your mushrooms will likely grow in spring, summer or autumn months depending on the time of planting. They will not generally fruit in winter, but it is fine to plant your kit any time of year and simply wait for a change in seasons. Depending on when you plant, your mushrooms will be ready to harvest in 2- 6 months.
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When your mushrooms begin to sprout, make sure to keep their bodies moist by using the sprinkle head on a watering can.
Step 5: When to Harvest
Let your mushrooms grow to the desired size, but harvest before the edges have started to fray. Your mushrooms may grow in one large cluster, or in several clusters across a larger area.
A cluster of mature blue oyster mushrooms
Several clusters of blue oyster mushrooms still growing.
Step 6: Harvest
To harvest, simply twist an entire bunch from the ground. Do not cut the mushrooms off at the base, as any leaving any bits of mushroom may attract slugs, bugs or animals that are keen to eat your mushrooms.
Clean your mushrooms of and dirt or debris. You can store you oyster mushrooms in the fridge for up to a week
Step 7: Initiating The Next Flush
After harvest, water your mushroom patch well to promote more mushrooms. Your next flush could sprout in as little as a few weeks, however they are most likely to sprout again when the season changes. You should expect two to three crops of mushrooms before the growing medium is spent and you are left with your bed of mushroom compost.
Tips:
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You can try refreshing your mushroom patch by gently raking the top and adding fresh, hydrated organic materials on top after 6-12 months.
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Once your patch has matured (12+ months), check that there is still healthy white mycelium growing by gently digging down to inspect the lower layers. Material with healthy white mycelium growing on it can be used to start another mushroom patch!
Step 9: Mushroom Compost
Did you know that fungi play a key role in storing carbon? Trees and plants remove carbon from the atmosphere and fungi break down plant waste to create new carbon-rich soil. Clean air, healthy soil and delicious mushrooms: just one of the many ways fungi are incredible!
Mushroom compost is a valuable resource in the garden due to its high moisture holding capabilities. It is best used as a base layer for planting to help protect plants against drought. You can dig up and transplant your mushroom compost into the garden, hanging baskets or pots.
We hope you've enjoyed growing your mushrooms!
We're passionate about sharing the diversity of the fungi kingdom & making more of its edible & medicinal delights easy to grow. Want to try another strain or learn how to cultivate mushrooms? See our full range of mushroom growing kits and cultivation workshops!