A lab in the dark

Foraging for mushrooms can be perilous, but a sustainable food production venture has launched growing kits to help you harvest oyster mushrooms at home

 Oyster mushrooms being grown by Andrew Douglas of Dublin’s Urban Farm and Mushroom City in Dublin. Photograph: Richard Johnston

Oyster mushrooms being grown by Andrew Douglas of Dublin’s Urban Farm and Mushroom City in Dublin. Photograph: Richard Johnston


If you’ve ever gone foraging for wild mushrooms, then you might agree with me when I say that it’s an experience loaded with more than just the occasional frisson of danger. Surely I’m not the only craven person who, faced with the chances of confusing a tasty edible variety with one that’s hallucinogenic or deadly poisonous, soon comes to the conclusion that acute liver failure is, ahem, perhaps a risk not worth taking. Growing your own mushrooms, on the other hand, sounds a far safer bet.

If a new venture on the part of Andrew Douglas, the brains behind the Urban Farm roof garden project in the heart of Dublin city centre, comes to fruit, then that’s exactly what many of the nation’s gardeners will be doing this autumn. High up above the city, in the upper storeys of the building known as the Chocolate Factory, is Douglas’s make-shift but futuristic-looking laboratory where for the last year or so he has been experimenting with different food growing projects as part of his interest in sustainable urban food production.

Next to the trays of leafy greens growing under artificial lights and the bubbling fish tanks filled with trout and goldfish (all part of the Urban Farm’s trial aquaponic systems where the nitrogen-rich water from the fish tanks feeds hydroponically-grown plants), is what looks like a rather swanky, silver tent. A self-confessed science boffin, Douglas jokingly calls this his “mushroom inoculation chamber” but in fact it’s what’s known as a grow tent, of the type particularly popular with “purveyors of illegal drugs”. Except that there are no cannabis plants inside this one, but instead some small plastic wrapped bricks out of which oyster mushrooms are growing, their golden, shell-like caps gracefully erupting from small slits in the packaging.

Closer examination reveals that the bricks are made of tightly-packed coffee grinds mixed with a little damp cardboard or paper pulp, which Douglas says is the perfect growing medium for these fungi (other suitable materials include sawdust or even a dampened loo roll, or paperback book). Once inoculated with the mushroom spawn, covered with plastic, and kept in a warm place, the grinds gradually become colonised with the fungal mycelium (the pale-thread-like precursor to the actual mushroom). These mycelium are eventually followed by the ‘pins’ or baby mushrooms, which within a few days will grow to full size.

As a relatively safe and easy way to grow a food crop, it makes a lot of sense. All the more so when you consider the cost of oyster mushrooms (anywhere from €12-€24/kg) in shops and the food miles embedded in them. Add to that the fact that coffee grinds are a by-product of the catering industry – every year, the world produces an estimated 12 million tons as a waste product – and you can understand why Douglas is enthusiastic about the possibilities of home mushroom-growing as a sustainable food crop.

“It’s a very productive and imaginative way of upcycling organic waste to produce a tasty, low-cost and highly nutritious food. Not only are they delicious but studies suggest that oyster mushrooms are rich in natural statins, which help lower cholesterol levels.”

Douglas hopes that the project might develop into a more permanent business, one that could eventually produce a range of delicious, locally-grown mushrooms for Dublin’s restaurants while simultaneously reducing their waste disposal costs. “The average yearly consumption of mushrooms per Irish person is tiny in comparison to somewhere like Hong Kong, where it’s 17kg.”

Which brings us back to the launch of Mushroom City, the new non-profit pop-up farm project (October 14th-December 14th). Using 2,000kg of coffee grinds collected from eight city centre coffee-shops, Douglas is planning to create what he calls mini oyster farms; a handy mushroom-growing kit comprised of 1kg of coffee-grinds inoculated with oyster mushroom spores, which comes with its own miniature water mister and which can be posted out to customers. “As long as the inoculated mix is kept at the right temperature (in a well-lit, warm but not hot room, out of direct sunshine and cold drafts), and regularly misted with a water spray, customers should see the first signs of mushrooms within a week and be able to start harvesting within a fortnight.” He expects each kit to produce two to three flushes of mushrooms over a period of several weeks.

The Mushroom City Project is only one of several sustainable urban food projects that Douglas has on the boil. Next in his sights is an edible insect farm, where the dead, dried insects will be made into a sort of protein powder/flour. “Cricket crackers … it has quite a ring to it, don’t you think?”

For details of the Mushroom City Project, see mushroomcity.ie. For online stockists of a range of mushroom spawn suitable for home-growing, see mushroombox.co.uk

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