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.