Mushroom Propagation Trials #2

The results of my most recent experiment with propagating the stem ends of store bought oyster mushrooms still remains inconclusive (you can read all about my initial success in Mushroom Propagation Trials #1). After the entire inside of the plastic bag was colonized, I transferred the heavy and healthy-looking mass of mycelium to a large clean mason jar. I saved up frozen coffee grinds from previous servings in a clean plastic tightly sealed container in the freezer until I had enough to fill the jar. First I filled the jar roughly halfway up using a sterilized spoon and then I dropped, right from the originally cultured plastic bag, the mycelial mass straight onto the grinds in the jar. I then promptly covered the mycelium in more coffee grinds right to the mouth of the jar and sealed it with a sterilized lid.

There might be something happening out of sight, which is what I hope, but there’s no way of knowing for now. If there is no activity in another week or so I will take a look inside the jar but will probably find that the transfer was not successful. Transferring and moving the mycelium around is always risky business unless you feel that your culture is growing quickly and particularly aggressive. It doesn’t hurt to baby them, and this is clearly one thing that I ought to work on a little bit more. Generally it’s just a good idea to culture and fruit your mushrooms in the same container, although this does have it’s own unique problems (such as the mycelium taking too long to colonize which leads to contamination issues). There is no single right way to do it, it’s just important to try and figure out what works best for you given your own observations and unique tools and equipment.

Recommended equipment for mushroom propagation
Recommended equipment for mushroom propagation

Anyhow, this is what I have gotten up to lately. Fearing my latest experiment may not have panned out, I went again and purchased some oyster mushrooms from my local grocery. In my last article I was quite indecisive about the species that I was purchasing to use in these experiments, but the batch that I purchased recently appear to be more akin to the blue or pacific oyster, Pleurotus columbinus, which is exciting. I have never worked with this species before, but I have read that it is just as adaptable as the more common Pleurotus ostreatus in terms of suitable substrates i.e. used coffee grinds and other largely cellulose or lignin based materials. Below I have written my materials & methods regarding the specifics of how I went about dividing and propagating the stem pieces. I’ll most definitely learn something from these trials, but what I am really hoping for is for a strong, successful colonization of a starter.

Over the course of March 13th & 14th, 4 different mason jars have been inoculated. Two contain just plain used organic coffee grinds, the other entirely used yerba mate, and the last a mixture of half and half coffee grinds and yerba mates leaves for a total of 4 starters. Yerba mate is a caffeinated herbal stimulant used as an alternative to coffee, although it contains additional stimulating compounds such as theobromine, which is also found in chocolate. It is made from the smoked, cured leaves of the tropical Ilex paraguariensis, a close relative of ornamental holly (that squat prickly bush with the shiny leaves and persistent red berries). I have taken quite a liking to yerba mate and have been drinking it every now and then for years. Since I use so much of it, I wanted to see if I could get oyster mushrooms to grow out of it. My thought is that the tea is pretty much all leaf material, which is high in cellulose, which oyster mushrooms love. Just a thought, so we’ll see what happens.

From left to right: two coffee starters, half and half yerba mate and coffee and one yerba mate starter
From left to right: two coffee starters, one yerba mate starter, and one half and half coffee and yerba mate starter


– smooth, clean surface
– rubbing (isopropyl) alcohol
– cotton ball
– small cup or shallow bowl
– 3 wide-mouthed mason jars with lids
– spoon
– tongs or tweezers
– scissors
– fresh oyster mushrooms in clusters
– coffee grinds – freshly brewed and cooled to room temperature or thawed from frozen
– freshly brewed yerba mate tea


1. Gather all of your necessary materials (obviously) and select your work area.

2. Pour some of the alcohol into your cup or saucer. Take a cotton ball and gently dab it into the pool of alcohol. Sterilize the work surface immediately in front of you using the cotton ball, as well as the insides of the mason jars, their lids, and all of the tools you will be using. It’s also a good idea to wash your hands and try to not touch anything that isn’t sterilized or reasonably clean. An alternative to using a cotton ball soaked in alcohol is to put the alcohol in a small spray bottle and spread it around/wipe off excess with a cloth. Your choice.

3. Open the container that holds your substrate and using your sterilized spoon gently break up the material and place them at the bottom of one of the jars.

4. Remove the oyster mushrooms from their container and select a piece at the base of the cluster to remove, preferably a piece that is white and fuzzy: evidence of healthy mycelium. Sever this piece using your sterilized scissors and then place it inside the jar on the bed of substrate with your tweezers or tongs.

5. Quickly but gently cover the transferred oyster mushroom stem piece with more substrate until it is just covered. Replace jar of lid.

6. Place jar in a cool, dark place with a consistent, slightly warm ambient temperature such as 70-75°F (20-26 °C). Open the jar briefly each day in order to allow the culture to breathe. Add more substrate to the jar as the mycelium invades and digests what is available. You don’t want to put in more than your mycelium can consume in a few days or you risk contamination, but do try and keep up with it. Definitely check on your new buddy everyday.

After 2 days of growth, one of the plain coffee starters already is showing some activity
After 2 days of growth, one of the plain coffee starters already is showing some activity

It’s also a good idea to work diligently, but still carefully, when you are adding substrate, your stem cutting and more substrate to cover it. The less amount of time that your culture and substrate is exposed to the open air, which is full of fungal and mold spores, the better. But of course you should still be careful to avoid knocking the jars or anything else over or spilling substrate all over the place and wasting it or introducing contaminants which could ruin your batch. I have read many different sources that advise using a glove box for all of the above open-air transfers but I am confident that isn’t necessary for Pleurotus species, since they are comparatively aggressive compared with a lot of other cultivated edible mushroom species. Stay tuned for updates in the coming weeks!