If you want to try growing mushrooms at home, start with Oyster mushrooms. Their growing medium – usually straw – is easy to come by, and the only other materials you need are a plastic bag to put everything in, and the spawn itself. Oyster mushrooms have a wonderful ‘horn of plenty’ shape, and a delicate and distinctive flavour.
What you need
Wheat straw works perfectly well and is the easiest to find, but any type of agricultural straw will do. Don’t use dried lawn clippings – this is not the same! They’ll have a far less substantial structure than straw and you’ll probably end up with a slimy, aerobic mess.
Straw, on the other hand, is nutritious and easy for the mycelium to break down. You can often buy it from garden centres and feed stores, but a drive into the countryside may get you a whole bale for between £3 and £8, depending on how generous the farmer is feeling. Most farms use straw, and if you only want a half bale – more than enough to grow your first mushrooms – they will probably be happy to split one for you.
Growing Oyster mushrooms – getting started
The straw must be sterilised before the spawn is mixed in, otherwise you risk contamination from other moulds and fungi.
Use the biggest pot that will fit onto your stove-top. Stuff it with as much straw as you can, and then fill it almost to the top with hot water. If you have a big wire basket of some kind, great – as the straw can be lifted out of the water when it’s sterilised. Otherwise you’ll be tipping the water out instead. If you do this, be careful. Make sure everyone – especially family pets and small children – are all out of the way when you do this.
The pot should be heated until the water is between 70-75 degrees Celsius. Keep it at that temperature for about an hour. You may need to top up the water, and all the straw should be kept below the surface.
Once you’ve either tipped out the water or pulled out the straw, lay it out on a plastic sheet to drain and cool. Again, be careful. Wet straw is heavy, and difficult to deal with.
Adding the spawn
Fresh Oyster mushroom spawn can be bought in wooden plug form from Suttons Seeds. While these are intended to be put into holes drilled into logs, as with shiitake mushrooms, you can also use them to innoculate straw. It just takes a little longer for the mycelium to get going. However, the best way to innoculate straw is with the spawn supplied with one of Suttons’ oyster mushroom kits. The kits may look a bit pricey in terms of the expected harvest, but the spawn provided is not in dowel form. Rather than adding it to the small amount of straw that arrives with the kit, you can add it to a much larger quantity that you’ve prepared yourself for a much bigger return.
Don’t mix the spawn into the straw until the temperature has fallen below 35ºC, or you will kill it. Break up the spawn and sprinkle it onto the straw, and mix it in a bit. Then put the straw/spawn mix into black plastic bags and squeeze most of the air out before tying them shut.
If the bag is then left in a dark place at room temperature the mycelium will develop without any further intervention. After a couple of weeks, cut some slits here and there on the upper surface of the bag. This is where the mushrooms will appear. Their growth is triggered by light, but not direct sunlight – that’s too strong. If the straw dries out below the slits, spray with a mister to keep things damp – but not dripping wet.
Eventually, between three weeks and a couple of months later, you should get your first mushrooms. After the first flush, add a little water to the straw and they will probably go on to produce a second round. Eventually the bag will stop producing, and you will need to do it all again.