Growing Oyster Mushrooms

Why?

I’ve been wanting to grow mushrooms for a good while now and have finally got round to giving a go after my friend Gaetan gave me a massive bag of douglas fir shavings. After a bit of reading it seems the easiest mushroom to grow with a high chance of success is the Oyster mushroom!

Required Items

Buckets
I bought 2x 25L buckets with lids for £13.69 each. Traditionally mushrooms are grown in bags but I wanted to be as environmentally conscious as possible and reuse my growth container. Buckets it is then! I drilled 16mm holes in a alternating pattern for the mushrooms to grow out of.

Spawn
I bought 1L of spawn from Urban farm it for £15.99 but I should have bought their wholesale spawn here for £8.47. I don’t think there is any difference in the product…

Substrate
Mycelium can be grown in a variety of media: coffee grounds, straw, wood shavings, and more. I was given douglas fir shavings so i’ll use them.

Pasteurisation Chemical
In order for the mycelium to grow and not be out competed by bacteria, the substrate must be pasteurised. The method I have chosen is called cold water pasteurisation and involves the use of calcium hydroxide $(Ca(OH)_2)$ which raises the pH and kills the bacteria. I bought 1kg from here for £11.95

Preparing the buckets

I added 50g of calcium hydroxide to roughly 30L of water, mixed it in and then added the wood shavings until thick. I left it in the shed for 24 hours and then drained for an hour. The mulch is ready when the wood shavings are mostly dry but still slightly damp. The aim is to avoid rotting but still have moisture for the spawn to grow in.

In layers I started adding the substrate followed by the spawn which i crumbled in. The ratio of spawn to substrate should be 1:10. This meant that with my 1L of spawn I was only able to fill roughly half a buckets worth.

Inspection

After a week I inspected the bucket to see if the mycelium had taken and it had! This shouldn’t really be done due to contamination but I was curious…

A couple of days later.

Harvest

Three weeks have passed and it’s time for harvest (2nd December). All in all I managed to grow 620g of Oyster mushrooms in the first flush. The mushrooms should have been harvested a couple of days before but I was working away and wasn’t able to monitor their growth. Hopefully the second flush gives at least 60% of the first harvest.

Round 2

Alrighty then, It’s been waaay more than 3 weeks. It’s now 23rd of January. Some 7 weeks later and I finally have a second flush of mushrooms. Now, the weather has been cold, a couple of weeks below -5C, which isn’t good for growth. Grey oyster mushrooms like to climates between 10-20C… So, no wonder it’s taken so long. The yield was pretty terrible too. I was hoping for a third of the first flush but ended up with 132g.

Round 3

There was a 3rd flush but unfortunately I didn’t take any photos. From what I remember it was in the realm of 50g.

The End

For my first attempt, I was hoping for a higher yield per flush, but in hindsight it was very cold in the shed during this time. In preparation for the next attempt I threw the remains into the compost heap and had a look at the cross section of the mycelial block. I was surprised to see how little of the sawdust was impregnated with mycelium. I wonder if the substrate was too dense or the ratio of spawn to substrate was wrong.