Low Tech Oyster Mushroom Cultivation in Jars

This is a very low tech method for growing oyster mushrooms indoor. Ideal for small scale growers and absolute beginners.

What we need (per jar):

1 canning jar (1500ml)
250ml oyster spawn
1 small bottle (100ml) or something similar shaped
Straw (any straw-wheat, barley, rice etc.)

1st step: Fill the jar with straw and put the small bottle (I used an empty bottle of rubbing alcohol) in middle of the straw. Keep the lid on the bottle to prevent it from running full of water in a later step.

The straw stalks should be about 2-5 inch long. Squeeze the straw in really hard. You want to get as much straw into the jar as possible. Don't worry, even when squeezed hard, with straw this size there will still be enough air in the substrate. There shouldn't be any air pockets in the substrate. Now and then I also added a table spoon of dried coffee between the straw. Fill the jar with straw to about 1 1/2 inch below the rim.

Now select a small amount of small straw particles and fill them into a small canning jar. I use these to get an even/flat surface on the substrate.

2nd step: Pour boiling water in both jars, filling them to the rim. Put the lids on both jars and let them cool off to room temperature. Depending on room temperature this can take up to two hours or longer. The temperature should'nt exceed 77F/25C. Higher temperatures can harm the spawn later on. Don't use lids with a build-in air filter at this stage.

Large jar:

Small jar:

3rd step: Once the jars have cooled down to room temperature pour off the water, close them with their lids again and put them upside down on your working table. This allows the water to completely drip off.

4th step: Once the water has dripped off open the lid (while still holding the jar upside down) and let the water above the lid run off. Now put the jar upright again and pull the small bottle out of the substrate.

5th step: Now fill the hole with your oyster spawn. In this example I used home made oyster spwan on coffee grounds. Also cover the whole surface of the substrate with a thin layer of spawn. Don't squeeze the spawn too hard into the hole. Just sprinkle it in with a spoon.

Now cover the surface with the small straw particles to about 1/2 inch below the rim. 

Close the jar with a lid with a build-in air filter (coffee filter, polyfill, tyvek or whatever filter material you have at your disposal) and put it in a safe place without direct sunlight or too much air flow.

After about a week you will see the first mycelium strains appear.

3-4 weeks later the jar should be fully colonized.

Once the substrate is completely white it's time to open the lid once a day to catch the moment the first primordia appear. When you notice the first primordial grow set the jar on your windowsill and spray it's surface lightly with water. It should be moist, but not soaking wet. Just enough to prevent it from drying out.

In most cases the first primordia will abort. Probably because, without the lid, the substrate receives more air and gets a new growing impulse. But don't worry, this isn't a problem. Just keep spraying the surface and wait for the next primordia. This can take 7-10 days.

Day 41: The first surviving primordia have appeared and reached a stage at which they will no longer abort.

Day 43: The mushrooms got a lot larger by now.

Day 45: The mushrooms reached their final stage. At least i harvested them at this point. The weight was about 50 grams. Not that much, but of course you aren't restricted to make only 1 jar.

From the other side:

2nd flush: The first flush seems to have used up most of the jars nutrients. It took a couple of weeks for the next flush to appear and it produced only two mushrooms.

 

Although the yields aren't that great with this method jars like this fit on every windowsill and are ideal for small scale growers. It's also ideal for beginners to fully understand the growing proces of oyster mushrooms so, if they wish, they can use larger containers for future grows.