If you’re just starting out on your mushroom growing journey (in the legal sense of course!), then you won’t find better than an Oyster mushroom grow kit.
Oyster mushrooms, with the Grey Oyster (Pleurotus ostreatus) the most common edible in this range, are by far and away the easiest edible mushroom to grow.
They’re not fussy, the mycelium is aggressive, and they grow on all kinds of substrate. To top it all off they’re very tasty and they’re good for you too!
Most oyster mushroom kits these days are based on using straw as a substrate, and the grow kit consists of a plastic bag stuffed with oyster and a sachet of spawn. You can grow oysters easily on straw and wood-based products - paper and cardboard are other popular choices for oysters.
The spawn (which is a bit like the seed used to grow the mushrooms) that come with these grow kits are usually grain based - rye grain is a popular choice of substrate for the spawn, but coffee grounds are another great one to use as they’re making use of what would be considered a waste product.
To start things off you simply have to soak the straw bag in warm water, drain then add in the sachet of spawn once broken up. Mix it all around and place it in a warm place (30 degrees) to allow the mycelium to colonise the straw - this is known as the incubation phase.
Once the straw gets covered in a white cottony substance (mycelium) you can then transfer to the next stage, known as the pinning phase. This is when you want to encourage the mycelium to start pinning - where tiny mushrooms will begin to form!
The grow bag should be moved somewhere far cooler (between 0 and 5 degrees) to “shock” the mushrooms out of their slumber. There should be some light present here - darkness should be avoided as oysters need the light to form.
Once you do see tiny pins forming (you need to look very closely!) you’re ready for the fruiting phase. Usually it will take about 10-15 days to reach this stage, depending on a few factors including the vigour of your spawn and the strain of oyster mushrooms you’re growing.
The fruiting phase needs a cool but not cold temperature (remember, oyster mushrooms are usually a cold-weather variety, although you do get warm weather varieties too) and will need lots of fresh air. Place them in a light garage where it’s a bit damp but where there’s fresh air flowing. Aiming for around 10 degrees would be good at this stage.
The fruiting phase is the last step where you’re actively encouraging the mushrooms to form so as well as having the right temperature you need to also provide the right humidity levels, which is often where most grows fail. Oyster mushrooms will want a humidity of around 80%.
Invest in a decent hygrometer to allow you to check this, and you’ll want to be monitoring this level constantly - otherwise your mushrooms might fail to form (disaster!).
Once they do begin to fruit it might be as quick as 3 or 4 days before the mushrooms are fully formed and ready for eating. You need to wait until the cap of the mushroom is just about unfurled, before they are releasing lots of spores into the air.
At that point you should cut the stem with a knife, trying not to cut too deep through the mycelium itself but keeping the cut flush with the grow bag. Keep in the fridge until you’re ready to eat.
Often with oysters they will produce a second flush, maybe a week or 2 later, so don’t throw the grow kit away afterwards. Give the bag another soak, in cold water this time, and repeat the process above - you may get lucky.
If you don’t get yourself a 2nd or even 3rd flush then don’t worry, the contents of the bag make an excellent compost for the garden. And did you know that you can create your own oyster mushroom spawn from the stem butts from old mushrooms? Or, for the more patient growers, you could even take a spore print from an oyster and turn those spores into your very own mushroom spawn?
