Agar petri dishes is where the good work starts. It is used to clean spores and contaminated cultures, as well as, to clone and get copies from dried or fresh mushrooms, broadly speaking.
By transferring from one petri dish to another (T1, T2, T3…) you get to clean the culture and strengthen it to further make it into a liquid culture or to add to grains to make grain spawn.
A simple and efficient agar recipe is:
500ml of distilled water
10g of Agar Agar powder (found in Asian food shops)
10g of light malt extract powder – LME (found in brewery supply stores)
Mix ingredients in boiling water till everything gets fully dissolved.
20min in PC (pressure cooker) @ 15 PSI.Pour it before it solidifies (whilst still hot but not too hot).
PS: agar work demands a very clean environment, so I would recommend using a flow hood or at least a still air box (SAB).
After it cools down it will solidify and be ready to receive another agar piece, a liquid culture, spore print (though for spore print I would recommend water agar) or a tissue from your favorite mushroom.
There are two types of growth, either rhizomorphic or tomentose. The first is what you want if the idea is to grow mushroom from the culture, the latter is good to keep, store and to clean a culture. By reducing the amount of nutrients in the media you encourage rhizomorphic growth, in other words, because there is less nutrients the mycelium spreads faster to find food source.
You might use pre-sterilized petri dishes or glassware that needs further sterilization. Some people also use the no pour method where you pour the dishes and then sterilize them in the PC. I have never tried the no pour method myself but it seems to be more efficient in avoiding contamination if you do not have a flow hood.
Most people would use a scalpel to get slices of agar or mushroom tissue. Make sure you flame sterilize your scalpel every time you are making a new slice. In reality you may use any tool that can be sterilized.
It is normal to use food colouring in the mix to end up with colourful agar dishes. Some say it helps identifying contaminants and easy to keep track of number of transfers.
Once the culture is growing clean and strong you want to use it (cut a slice) and add to grains or a new dish. Try getting the strong looking part near the edges of the growth, looking for the ones that are expanding quicker. In order to save the dish for later use it is important to stall growth before the mycelium reaches the borders of the dish by refrigerating it (in case you are happy with the quality of your culture and want to store it).
Ideal incubation temperature for the mycelium to grow is 22 degrees Celsius. Refrigeration temperature (storage) somewhere in between 2 to 5 degrees Celsius.