Mushrooms are a popular ingredient in cuisines found all over the world. From a porcini pasta entrée laced with black truffle, to a Beijing dumpling filled with shitakes and wood ear mushrooms, the rich, umami flavour of mushrooms elevates even the simplest dishes.
While you might think that mushrooms can only be grown in subterranean settings and dark, humid climes, it is remarkably easy to grow them in your own garden. A polytunnel can help you create a robust crop of mushrooms year after year.
A polytunnel is a long frame covered in polythene in order to create a controlled climate in which to grow seedlings and plants. They are not typically used for growing mushrooms, as they are often used to create a sunny and bright growing environment. However, polytunnels do not have to be made with transparent materials. You can easily create customised covers that will restrict the light that makes it down to the soil.
If you are planning to set up a mushroom polytunnel, you should select a sheltered,
damp, and dark corner of your garden. Many savvy gardeners choose to set up their polytunnels beneath a tree. Conversely, you might want to set up a planter indoors – people have great success growing mushrooms in garages and sheds.
Mushrooms are planted using a method called inoculation. Yes, you read that correctly – mushroom spores can come loaded in a syringe! However, for edible mushrooms, the most common way to purchase the spores (mycelium) is in a soaked dowel (for growing on logs), or in spawn form for spreading around lawns or compost.
Do you have a neglected patch of lawn you aren’t using to its full potential? Maybe you have space around your compost heap? These can both be ideal places to plant mushrooms.
In order to get started, you need to create a mulch bed (also called a mushroom patch) into which you will inject or plant your mushroom spores. These beds are made with wood chips, bark, cardboard, mulch or straw. Once you inoculate the bed, you should be able to harvest mushrooms for the next few years. At this point, you will likely have to refresh with new material and re-inoculate with spores.
Start by setting up and lifting 25cm (10 inch) squares of soil or turf up to a depth of 4cm. Leave at least 60 cm (24 inches) between each square. Carefully loosen the soil or turf beneath the squares with a trowel or garden fork. If your soil or mulch is poor in quality, add rotted manure or more compost to the area.
Thinly spread the mushroom spores/spawn across the surface of the soil, and mix it down to a level 1 cm deep. Add a layer of turf or mulch over top, and add enough water to keep moist (but not waterlogged).
Remember - chemical fertilisers are a bad idea. Mushrooms do not thrive with fertilisers, and they will simply not grow.
If you don’t have space for a dedicated mushroom bed (or even a garden at all), you can still grow mushrooms. Some people have had luck growing them on books or even in a bag of mulch. You can keep these materials in a closet, cellar or any damp, dark place. Place a book soaked in mycelium spores in plastic, and then pop it in the fridge – this will encourage fruiting, and after this time you can return it to a dark location out of the way. Oyster mushrooms in particular respond well to this method.
One of the most common methods for growing mushrooms is on a log. Many garden centres or suppliers sell hardwood logs that have already been inoculated with spores, or you can turn this into a ‘DIY’ project by drilling the holes yourself. Once you have drilled appropriate holes in a log, you insert mycelium soaked dowels.
Tempted to use a log that has been sitting on your property for some time? Don’t do it. It is important to always use a fresh log so that you can ensure that no other potentially harmful fungi have already colonised the surface. Approximately 4 times per year it is a good idea to plunge your log into icy cold water. This will encourage the log to fruit and you should see a big bloom 10 days later.
Sowing in Autumn: From September to October
Sowing in Spring: February (if in polytunnel); otherwise, from March to Early June
From autumn sowings: April to May
From spring sowings: May to September
When it comes to harvesting your mushrooms, you have 2 main choices: should you cut the fruit from its stem, or twist the mushroom to pull it from the mycelium? The debate rages on, but in reality, it doesn’t matter which method you prefer! The easiest way to tell that that your mushrooms are ready is that they will start to drop spores. These spores look like a fine white “dust” spread across the surface beneath the colony. When you see this, it is time to harvest your mushrooms.
One of the main reasons that you should consider growing your own mushrooms is that you can control the exact conditions and settings. This ensures that you will not accidentally eat toxic mushrooms (or even just mushrooms that do not taste nice!). Foraging mushrooms is a safe and fun hobby, providing you know what you are doing. If you are not 100% sure about the type of mushrooms you are harvesting from your garden or the wild, you should err on the side of caution. Do not eat any mushrooms that you cannot be certain about. When in doubt, consult an expert.