A polytunnel may be customised to make the perfect environment for mushroom growing. If you wish to create a large scale or commercial mushroom growing venture then creating a dark polytunnel rather than purchasing an expensive garden building or shed could be the answer. Most polytunnels, however, will be too sunny, bright and dry for mushrooms to thrive with conventional covers, so a special cover that restricts light should be used. Mushrooms are best grown in a sheltered location – ideally a darker, damper corner of the garden, perhaps beneath a tree. Mushrooms can also be grown indoors in a dark spot, or in a garage or shed.
There are a number of different methods from growing mushrooms in the UK. The simplest is perhaps to create a mushroom patch, or mulch bed, into which you add mushroom spores or, for ease for beginners, dowels that have been inoculated with mushroom mycellium. Stropharia is one type of mushroom that can be grown in this way. Once you have inoculated the mulch, wood chip, bark, cardboard or straw of your mushroom patch, you should get fruits for a few years before you need to add new material and re-inoculate.
Another way to grow mushrooms is on a book or in a bag of mulch materials which can be kept in any damp and dark place. Putting a plastic covered book that has been soaked and spawned into the fridge will encourage it to fruit. Oyster mushrooms are one type that can be grown using this sort of method.
Another option is to inoculate logs with mushroom mycellium. You can either buy a hardwood log that has already been inoculated or you can do it yourself by drilling holes and inserting dowels that are covered with mushroom mycellium. It is important that fresh logs are used so that no other fungi has been able to colonise the log already. It is best not to use logs cut in spring in which the sap is rising. Once the mycellium has colonised the logs and they are mature, the logs can be plunged into freezing cold water up to four times a year for a couple of days, which will encourage fruiting. Oyster and shiitake mushrooms are examples of types that are grown in this way.
One of the good things about growing your own mushrooms in controlled conditions is that you can be sure that you will not eat the wrong sort of mushroom. Whether in your own garden or out foraging, it is important not to eat any mushrooms that you re not 100% sure that you have identified correctly. Inexperienced foragers should never eat mushrooms without checking with someone with more field experience.