Weekend gardening: Growing mushrooms

Weekend gardening: Growing mushrooms
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Would you like to have your favourite mushrooms on hand to give their delicious fresh flavour to your stir-fries, soups and sauces? Find a little corner, choose your substrate and get growing!

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Why bother growing mushrooms? Well, I love mushrooms! I love watching them grow, eating them, making dyes and artefacts with them, even making tea from them.

As any good gardener knows, fresh home-grown produce tastes much better than anything you can buy from a supermarket. In Australia, most of the gourmet mushrooms for sale, such as shiitake, oyster, enoki etc, are imported from Asia. They are not fresh and they are usually not organically grown.

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When you grow your own mushrooms, you can choose the substrates to grow them on, such as logs or straw or even coffee grounds and tea bags. You can also pick them fresh as you need to use them.

People have been growing and harvesting mushrooms for centuries. The delicious pioppino (Agrocybe aegerita) was cultivated by the Greeks and Romans on black poplar (Populus nigra) while, in Asia, similar methods were used to grow shiitake (Lentinula edodes) on oak and shii trees (Castanopsis cuspidata).

 

Log on

A traditional way to grow them is by simply gathering limbs with the desired mushrooms already growing on them, then stacking fresh limbs so they are in direct contact with the mushroom-infected limbs so the new limbs eventually start to grow mushrooms of their own.

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These days, though, you don’t need to find a log with mushrooms already growing on it. You can use various forms of spawn, such as wood dowels or grain spawn, which have already been inoculated with mycelium from your desired mushroom species, and introduce them to your log.

Mushrooms are the fruiting bodies of various fungi, but much of the organism is made up of mycelium, fine threads — often white — which are very easy to catch and grow.

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Usually, you drill a hole into your log, then insert the spawn and seal the hole with wax. I mainly use eucalyptus species, but many other hardwoods (flowering trees) will also work. Mushrooms will start to form usually within six to 12 months when the conditions are suitable, which in nature tends to coincide with rain.

Mushrooms are 90 per cent water, so you do need to hydrate your log. A simple way is place one end of the log in water. Logs that are looked after can continue to produce mushrooms for many years.

 

Log alternatives

What if you can’t find suitable logs, or don’t want to wait up to a year for your first harvest? No problem. Many species of mushroom can be grown on other substrates, such as straw, sawdust, woodchips, paper, cardboard, even teabags and coffee grinds.

The easiest species to grow would have to be the oyster mushroom (Pleurotus species). They grow quickly, can tolerate a wide variety of substrates and come in a range of colours. In Tasmania, we get to enjoy golden oyster (P. citrinopileatus) in summer, while the blue (P. pulmonarius), white and grey varieties (P. ostreatus) fruit throughout the year.

 

Growing

Very few organisms are capable of digesting wood, but the gourmet mushrooms I grow are wood lovers. When using wood-based substrates, there is very little risk of contamination. When we use substrates such as straw or coffee grounds, however, many other organisms are already in the substrate, ready to compete with our mushrooms. To give our mushrooms a head start, we need to kill off most of those other organisms, usually with heat.

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Hot water — between 60°C and 75°C — is sufficient to “pasteurise” our substrate, killing most insects and competitor fungi. A simple method for home cultivators is to place your straw in a bucket, then cover with hot water at 75°C. After two hours, drain off the water and, when cool, add your spawn — usually grain spawn.

Your inoculated substrate can now be placed in a cardboard box, plastic bucket or special filter patch bag. You will want to protect your substrate as much as possible from insects, which is one advantage of filter patch bags, as you can seal the bags. Fruiting starts within two weeks and can last several months.

Another popular method of growing some species of wood lovers, such as king stropharia (Stropharia rugosoannulata), is to soak woodchips in water for at least a week, which hydrates and conditions the woodchips. This method is good for outdoors as the water creates an anaerobic environment, which can get a bit smelly.

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Choose a place in your garden, such as under a tree, and then lay down a few sheets of newspaper and/or cardboard. Tip your bucket of soaked woodchips on top and mix in some spawn. You can add a top layer of more woodchips, or sand, gravel, sawdust etc, which will deter birds and rodents from eating your spawn. The mycelium will rapidly turn the woodchips into mushrooms, leaving behind a rich, porous soil.

Home-grown mushrooms are delicious, easy to grow and full of protein, vitamins and minerals — so why wouldn’t you bother to grow them? Forest Fungi (forestfungi.com.au) runs courses on how to grow your own mushrooms and also sells equipment and supplies for home mushroom cultivation.

 

Health benefits

Mushrooms are not vegies or fruit. They’re not even plants — they’re macrofungi. However, they offer many health benefits that make them complementary to fruit and vegies in the diet; in fact, you could replace one of your five serves of vegies with a serve of mushrooms.

Mushrooms produce vitamin D when exposed to sunlight, converting their abundant ergosterol to ergocalciferol (vitamin D2). Commercially grown crops aren’t generally exposed to the sun, but you can give your own home-grown mushrooms a blast of sunshine after harvesting to make them rich in this important vitamin.

Shiitake on sawdust

They also contain beneficial amounts of the vitamins B2, B3, B5 and folate, as well as significant amounts of the minerals chromium selenium, copper, phosphorus and potassium.

These little powerhouses help fight cancer, help keep blood sugar and blood pressure levels normal, are good for heart health and are among the highest-antioxidant food, thereby boosting the immune system. On top of all that, the biotin content makes them good for skin and hair and, being low in kilojoules, they are excellent for weight management. So they taste good, are good for you and help make you look good! What more could you ask for?

 

Words & photos by Will Borowski of Forest Fungi

Originally from Good Organic Gardening magazine, Volume 6 Issue 1

Publish at: , last modify at: 14/05/2015

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