Mushrooms

Edible mushrooms are increasingly popular as a food source. They mainly grow on waste materials which makes them ideal for use on recycling products such as straw, wood and compost.

Cultivation is known about over a thousand years ago. Growers in olden times gathered turf and logs from fields and woods and then inoculated these with spores or added them to other materials where the spores in the collected materials infected others. We can now source over 30 different species.

Cultivation

The spawn (spores) from cultivated species are produced in cultures of fungal material known as mycelium. These are usually grown on cereals like wheat and rye or produced on sawdust. The mycelia can be inoculated into freshly cut hardwood logs, hardwood dust and chips, coffee grounds, straw, paper and even toilet rolls. I have seen fermentation medium growing within pantyhose and nylons, plastic bags etc. When starting out with growing, choose an established brand usually via a kit because this contains the spores and the substrate on which to grow the mushrooms. 

Innoculation

When the spores are added to the substrate, allow to settle then grow on within the substrate. The substrate is often kept in plastic bags because this retains moisture which is always needed for mushrooms to grow well. Moisture and a slight musty smell will develop but this is OK given that mushrooms are growing rapidly. The mushrooms will develop from the mycelia which always develop first. Keep the bags in the warmth and dark. High levels of carbon dioxide form within the bags and should accelerate growth.

For growing mushrooms like oyster mushrooms in logs, use dowels full of fungal material and insert into preformed holes in the log. Allow for a period of incubation so that the fungi penetrate the wood cellulose and develops a mycelial system. Given wood is extremely durable and resistant even to fungal attack, it will be a few months before any developments occur.

Cropping

One the substrate is permeated with the fungal mycelia, place the log or substrate in a slightly cooler place with more air because this stimulates the growth of the desirable fruiting bodies. Cropping is always highly irregular because of the nature of growth but it is possible to see very heavy crop production. A continuous production requires careful planning but it is a little erratic at times.

Suitable Varieties

There are 30 varieties worth choosing.

Try Shiitake which comes from East Asia and is grown on logs. The mushroom has a mild flavour with a firm texture and is widely used in Asian cuisine especially stir-fries.

Oyster mushrooms also live on wood but can be raised on sawdust, toilet rolls and logs. There are many different types including pearl oyster, yellow oyster and Indian oyster. All have a mild flavour.

Issues And Problems

Sometimes other fungi can hitch a ride in the fermentation medium which can compete for resources. Always clean all equipment and keep substrates separate from other materials. If possible, heat treat the substrate to kill spores already contained. This can take the form of pasteurisation which normally kills pathogens and other spoilage organisms – the term means to reduce the level of pathogens to an acceptable level. Otherwise, full sterilisation of the media is needed.