Growing Edible Mushrooms at Home – First Tentative with Oyster Mushrooms

This fascinating experience begun as simply a challenge almost a game: is it really possible to grow mushrooms at home?

After checking some articles and buying some grey oyster mushrooms (Pleurotus ostreatus also called blue oyster mushrooms), I knew I would try this adventure!

I started oyster mushrooms as are easy to get from a good store and start with. I did not know a lot and it was a learning by doing.

Finally I have to say that growing oyster mushrooms is quite easy, and will continue to work on this great project and make some experiments.  I enjoyed very much watching the quick growth of the fruiting bodies, take a few photos to compare the growing status (size) and I can’t wait for the coming harvests!

I understood that there are many different ways to grow Pleurotus ostreatus at home and I’m sure I have a still a lot to learn about this, so that I will make it easier and getter better results.

Note: each oyster mushroom species has its specific “best” requirements for temperature, humidity, light, and nutrition.

1.         Starting from tissue of oysters mushrooms without a kit

The goal of this step is cloning a piece of oyster mushroom (your starting material) and preparing coffee ground spawn for the inoculation of your culture block.

In this step some oxygen is needed, for this reason do not close or seal the jars and the box, best once or twice a day open the cover of the box!


  • Coffee ground (after brewing), enough to fill 2/3 of the jars
  • Bowl
  • Water
  • Jars ( I made 3 of them in order to have some backups)
  • Empty tea bags or coffee filters
  • Rubber
  • Pressure cooker, microwave or canning pot
  • Sharp knife
  • Spoon
  • Kitchen gas burner
  • Fresh oyster mushrooms
  • Plastic box at least 10 times bigger than the volume of all jars together.
  • 1 layer of stones (or other material) about 2-4 cm high.


  • Place your used coffee ground in a bowl, add some water and stir until well moist but not too wet.
  • Fresh brewed coffee ground is almost pasteurized, but for this step, you need more than a small portion and you have to prevent contaminations. Fill your jars with the moistened coffee ground (about 2/3 of the volume). I used jars of about 400 ml as well as plastic bags for some more ready to use coffee ground. Place the coffee filters over the opening and fix it with the rubber so that only filtered air has access to the content. Another option is to use plastic bags with a pies of sponge as filter loosely closed with the rubber. Second alternative: pasteurize the jars with the content, the filter and the cover in the canning pot.
  • Sterilize the jars in the pressure cooker for about 30 minutes. First alternative: Place the coffee ground in plastic bags add little more water (about 10 ml water / 100 ml coffee ground) and place in the microwave at medium power for about 10 minutes (start taking the time from the moment that steam is coming out of the bag, then take out of the oven close the bag immediately.
  • Now you need to do is harvest a piece of tissue from a mushroom fruit-body (your store-bought oyster mushrooms).
  • Clean your working surface, wash your hands and rub them with some disinfectant. Open the jar carefully, keeping the inner part of the filter side up (should not touch your fingers or the working surface) For this step sterilize your knife with the flame, keep the knife shortly in the hand (do not lay it down on an unsterilized surface) until cooled down, cut the mushroom stem butt in half vertically and cut out a piece of tissue. With the point of the knife take the tissue and place it into the jar. Close the jar and tight the borders with the rubber again. Repeat with the other jars.
  • Prepare the box with the stones and add about 1 cm water.
  • Place the jars over the stones and cover loosely the box. At this point allow the mycelium to grow until you your will see that it is full colonized. From time to time check the humidity. Temperature: 22-24°C, Humidity: 85-95%, 2-3 weeks, no light.

2.         Inoculation of your substrate (Spawn run)

I used about 3 l of straw as substrate and inoculated it with 300 ml of coffee spawn.

For a bigger quantity of substrate you should increase the quantity of spawn for example inoculating your coffee spawn and an additional quantity of pasteurized coffee or layers of wet cardboard (same conditions as above) and wait until it is fully colonized. For the straw, a too long colonization, would increase the risk of contamination.

It would be easier to grow oyster mushrooms outside in a humid place, but now in winter, we have to do in indoor.

To sterilize the substrate outdoor, it would be possible to do it by fermentation under water (10 days), but for an easy a quick start, the best is to pasteurize the straw.

In this step some oxygen is needed, for this reason do not forget to make cuts into the bag and do not close the box tightly, best once or twice a day open the cover of the box!


  • 5 l bucket
  • 3 l chopped straw
  • Water
  • laundry bag or similar
  • 5 l Plastic bag
  • Big cooking pot or canning pot
  • 300-500 ml coffee spawn (see above)
  • Spoon
  • Kitchen gas burner
  • Plastic box at least 10 times bigger than the volume of all jars together.
  • 1 layer of stones (or other material) about 2-4 cm high.


  • Place the straw into the bucket and cover with water. Let soak at least two hours.
  • Drain until no water comes out.
  • Place the Straw in pillow case, nylon mesh laundry bag or similar, submerged in water and heated 80°C degrees for 1 hour (for indoors on stove top or in canning pot). Let cool down.
  • Put one quarter of straw into the plastic bag, add one third of coffee spawn; pay attention to remove the coffee from your jar with a spoon sterilized over the flame. Repeat with the next quarter of straw, the next third of coffee spawn, quarter of straw, last third of coffee spawn and last portion of straw. Note: if you want to keep some coffee spawn for the next time, add some sterilized coffee to the jar, stir and cover with the filter (work as in written above in chapter 1.4.).
  • Press the content to compact a little bit, close the bag tight and make about 10 cuts of about 1 cm into the plastic bag. Place the bag over the stones (should not touch the water) and cover loosely the box At this point allow the mycelium to grow until you your will see that the bag is full colonized. From time to time check the humidity. Temperature: 22-24°C, Humidity: 85-95%, 3 weeks, no light.

3.         Inducing primordia formation

Once the mycelium has completely covered the straw, it should be ready to start pinning.

After about 4 weeks I still did not see primordial (mushroom pins), and only after researching I understood, that at this point I had to reduce the incubation temperature as well as light. Now you know! J


  • I opened the bag (not necessary cuts on the sides are enough) and placed it in a cool and well lit room (about 8h light per day are needed, no sunlight). The temperature for blue oyster mushrooms should be around 10-18°C. If the place is too dry cover with a big plastic bag, but mist with water and open remove shortly the plastic about 2 times per day. This is to reproduce the fall conditions! In this stage they need more oxygen.
  • Around one week later you may notice the formation of the primordia. They look like tiny pins. It’s time for fruiting!

4.         Fruiting

Our baby mushrooms (primordia) are ready to grow; they need now warmer conditions and in any case light, but avoid sunlight.

The produced CO2 content has to be removed, for this reason I wrote that high boxes are not the best option. So I placed them on a cardboard box with holes and newspaper. The CO2 will drain out of the holes of the bag.

Fruit flies as well as other insects may be a problem, in this case move the culture in another place.

If in the garden, watch for snails!

  • Place the bag on flat box or tray or ventilate with fresh air and mist 3 times per day. A temperature of 18-21°C should work well.
  • In a few days the mushrooms will be completely developed, when the caps are flattening at the top or just begin to turn upright, it’s time to harvest.
  • Pinch the base of your mushroom and twist firmly, or cut them with scissors.

5.         Inducing fruiting for a second or more times

Usually the substrate has enough nutrients to activate the mycelium and fruit 2 to 4 times. Try if you are lucky!

  • Water and drain the bag with fresh water.
  • Reduce temperature and induce primordial as described above.
  • At the end of the cycle dispose the used straw by composting or in the rubbish bin.

6.         Prepare spawn for next bugs/bucket.

Now we need more spawn for some more mushrooms.

I will grow some on bigger portions of mycelium coffee ground for bigger straw bags or I will use some material from the stem of the new mushrooms and grow it into layers of pasteurized cardboard. In alternative I will use some “clean” mycelium form the coffee cultures and grow it into pasteurized layers of cardboard or soaked/sterilized grains.

Table of growing conditions for Grey/Blue Oyster mushrooms (Pleurotus ostreatus)

Stage Temperature Time Air Light
Spawn Run 22-24°C 2-3 weeks little O2 no
Primordia inducing 10-18°C 3-5 days more O2 indirect light
Fruiting 16-21°C 4-7 days drain CO2 more O2 8h per day indirect light

Slideshow: Growing during the first 8 days from the moment I noticed the primordia

This slideshow requires JavaScript.

1 thought on “Growing Edible Mushrooms at Home – First Tentative with Oyster Mushrooms

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