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One of the most common methods for starting a bulk mushroom grow is to use Rye Berries or other grain as a medium to spawn your mushroom spores. Rye berries are ideal for this purpose in providing the necessary moisture, nutrients, and are readily available online or at your local feed store.
This method will make approximately 7 quarts of spawn, which will produce upwards of 2-5 tubs depending on the size of the tub you will be using for your bulk grow. See our full guide on tub sizes and substrate to spawn ratio here.
For this Tek you will need the following materials:
- 2 quarts of Rye Berries, just under 3 lbs. Best price here
- 7, one-quart wide-mouth mason jars
- Lids with air exchange and injection ports – see our DIY or buy these premade here
- Mushroom spore syringes
- Large Spoon
- Gypsum powder
- Large cooking pot
- Large pressure cooker. See our recommendations for best value and best quality.
- Heating element – stove or otherwise
The first step in the process is to clean the grains to remove dirt and any impurities in our rye berries.
For this, we will wash them using hot water either in a pot or with the use of a strainer. I prefer the strainer, but you can use any container. Make sure to rinse the berries multiple times until the water runs clear.
Once clean you will put your rye berries in a large cooking pot. Fill the pot with warm water until the berries are fully submerged by 2-3 inches of water.
Next, you will add one tablespoon of gypsum powder to the rye and water pot. This is done to prevent the rye from sticking together. Mixing is not necessary as the gypsum powder will naturally suspend in the liquid.
At this point, we will cover the pot and let sit for 12-24 hours. This necessary step pre-hydrates the grains which helps prevent burst and also hydrates endospores which will make them easier to kill during the pasteurisation (sterilization) process.
After soaking for 12-24 hours you will place the pot on the stove at a high temperature. Dial the temperature back once boiling and allow the berries to simmer for 10-12 minutes.
Strain the berries from the water and allow to dry for 30-45 minutes. You can tell they are ready when they stop steaming.
Once dry it is time to fill our jars with the rye. Use your spoon to scoop the dry rye berries in your jars up to around the 600 ml mark; roughly ¾ full. You may have some excess grains remaining after filling up 7 jars.
Put on the modified lids and gently shake the jars. Your berries should not stick together, but rather move around in the jar freely.
Before sterilization, we will be wrapping the top of the jars with tinfoil. This is done to avoid additional moisture from seeping in through the holes in the lids.
Now its time to sterilize
Fill your pressure cooker with at least one gallon of water, secure the lid tightly, and place on your heating element. You will want to bring the pressure up to 15 PSI. Once there put a timer on for 90 minutes.
Once the timer has gone off, remove from the heating element and allow the pressure cooker to cool off. This will take a few hours depending on the surrounding environment.
Remove the jars, taking off the tin foil, and you are good to inoculate with the spores of your choice!