Oyster Mushroom Cultivation In Plastic Bottles

This time I tried something new. I had a large soda bottle (3 liter) and decided to use it for growing oyster mushrooms. Because of it's rather small opening it's difficult to fill the bottle with wheat straw. So I choose a mixture of coffee grounds and small pieces of wood. About 1 part coffee grounds to 3 parts wood.

I chopped up the wood myself, what was quite some work. In future I will try out some barbeque wood chips. Barbeque wood chips should be made of food quality wood and should not contain any harmful additives. Wood fuel pellets are another alternative but some companies  put additives in the pellets to make them burn cleaner. Before using them I must be sure they contain nothing else but sawdust. 

Hydrating small pieces of hardwood isn't as easy as when using wheat straw. It takes a couple of days before they are fully hydrated. I filled the wood pieces into jars, filled the jars with boiling water and put their lids on immediately afterwards.

Cooling off creates a subpressure in the jars and you hear a loud "click-like" sound when the lids are pulled inwards. It's best to pepare the jars 1-2 weeks before usage. This way one can be sure the wood is fully hydrated. Originally the jars were filled to the rim with boiling water. The empty space on top is a result from the air in the wood that was replaced by water. 

Preparing the jars 1-2 weeks before usage also serves another purpose than just completely hydrating the wood. If the wood wasn't fullt sterilized by the boiling water, contaminants will grow and will produce gases. This gases will produce an overpressure in the jars and will bend the lids outwards. As long as there is subpressure in the jars the wood should be sterile. If not pour off the water, rinse the wood under clean tap water, fill it back into the jar(s) and fill the jar(s) with boiling water again. This should kill all contaminants. To be sure leave the jar(s) for another week.

After filling the bottle with wood and coffee ground it took about 6 weeks until primordia formation. Unfortunately the the lower part of the bottle wasn't fully colonized at this point. 

Originally I intended to make a few holes in the bottle so that a few oyster mushrooms clusters would grow at the same time. The first primordia appeared at the surface, at the opening of the bottle. So I decided to just go for this cluster. Hopefully the bottle will fully colonize after my first harvest and I can proceed with my original plan.

First pins. For better fruiting I layed the bottle on it's side.

Four days later. I harvested them at this time.

Overal conclusion: Empty soda bottles are suitable for oyster mushroom cultivation and provide free growing containers for heavy soda consumers. One could prepare a number of bottles at the same time and use a wine rack to place them behind a window. For a more evenly colonization it may be better to let the bottles colonize in two steps. First the lower halfs and, after their colonization, the remainig upper halfs of the bottles.

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.

Oyster mushrooms on coffee grounds-Little experiment

In my opinion coffee grounds are perfect for making oyster spawn when using non-sterile techniques. However, in my experience, using them as a fruiting substrate never produced satisfactory results. They didn't fruit at all or produced nothing but crippled mushrooms. Usually the mycelium starts pinning but only produces some strange clumps that never develop into mushrooms.

Wheat straw however always works like a charm. Wheat straw works quick and provides perfectly normal fruits. Its only disadvantage is that it's very light. Meaning, by weight, one cannot get much substrate into small containers. So I decided to start a small experiment using coffee grounds as the major fruiting substrate, but topping it with a thin layer (about 1 inch thick) of wheat straw. The idea was that the wheat straw would produce normal oyster pins that then could profit from the heavier and nutrient rich coffee grounds. For fast results I used a relatively small jar with a capacity of only 500 ml. To compare the yields I also used a larger jar with a capacity of 1500 ml.

1st: Small jar experiment.

In order to get a evenly formed surface I only used the finer particles of my straw.

About 3 weeks later the first primordia appeared. Although still not perfect, part of the clump showed normal primordia.

2nd day:

3rd day: The majority of the pins have aborted. Only 4 of them had survived. Probably due to the small amount of substrate used.

4th day:

5th day: At this point the mushrooms were ready to harvest.The yield was rather disappointing. For a substantial amount of mushrooms one needs to make a lot of these jars.

2nd flush: The jars second flush. This time only 2 but larger and more healthy looking mushrooms.

3rd flush: Even though this flush started with more than 10 pins only 2 mushrooms made it to maturity. Obviously this small amount of substrate cannot support more than two mushrooms at a time.

2nd: Large jar experiment

This jar has a capacity of 1500 ml (still a rather low amount of substrate for growing oyster mushrooms) and isn't only wider but also a lot deeper. To provide the mycelium with enough air I applied three thin layers of wheat straw.

With this jar I used less spawn (about 20% of the substrate) and it took nearly 5 weeks for the first primordia to appear.

1st day:

2nd day:

3rd day:

4th day:

At this point I harvested the mushrooms. On the one part to prevent them from dropping spores and on the other part because it's winter and, as a result of the heating, the air in the room is rather dry. Resulting in cracked edges on the larger mushrooms. Nevertheless, in relation, this jar produced a higher yield, meaning that larger amounts of substrate always work better.

 

Conclusion: Although still not perfect, topping the coffee grounds with wheat straw produced quite normal mushrooms and can be a viable alternative for using wheat straw only. Nevertheless, as a fruiting substrate, I still prefer wheat straw. Wheat straw is more airy, holds more water and, in comparison, contains more lignin and cellulose, resulting in larger and better looking mushrooms. Although with straw it's better to use larger containers, it produces better results, causes less problems and is, especially for beginners, a better and fool proof alternative for coffee grounds or even sawdust.

It all depends on your goals. For sheer yields and ease of cultivation straw is always the better choice. But there are also people with a green lifestyle that want to recycle their coffee waste. No matter what the yields are. Adding a little wheat straw on top and into the substrate can prevent the problems occuring when using coffee grounds only.