Making Spawn Jars

Making your own spawn jars

Making your own spawn jars is a great way to start growing your own mushrooms. While relatively simple, you will need a few things to get started.

While making spawn jars is relatively simple, it may be a little daunting for your first time. Splurging on a pressure cooker/canner might not be in the cards. If that's the case, check out this page for beginners.

Ready to move on? Making your own spawn jars opens up a wide variety of mushroom growing techniques!

There are 6 steps to making grain spawn jars:

Step 1 - Soaking the grain

The most important part of a grain spawn jar is the grain!

You can use a variety of grains with success, but the most popular is rye berries. It has a great water capacity and is pretty durable. For more info on what grains you can use, check out this great article from FreshCap. You want the grain to absorb as much water as possible without splitting open or turning to mush. You also don't want to have excess water inside the jar that might inhibit the mycellium growth. Perfectly cooked grains leave enough space for air and mycellium, while also providing the moisture and nutrients that mycellium need to grow.

Soaking the grain is pretty easy. If you purchased food grade rye berries, you can soak in any bowl or pot. If you buy grain in bulk from an animal supply store, you may want to use something less food grade as many other things can grow while it soaks.

Whichever route you take, you will cover with a few extra inches of water and leave soak overnight and up to 24 hours.

Step 2 - Cooking the grain

A simple method is to bring your pot to a boil and simmer for 15 minutes. It's generally better to undercook it a little (especially if you soaked the grain), than overcook. Overcooked grain can slow down growth and make it difficult for the mycellium to spread and consume the grain.

Once the grain is cooked, let strain for a few minutes and then spread across a surface in as thin of a layer as possible. Typically, I will spread the grain on multiple baking sheets.

This allows the water on the grain to evaporate leaving a hydrated and dry grain - perfect for mycellium!

While soaking and cooking is generally the recommended approach, you can find examples of people having success with all sorts of methods and grains. Some people swear that soaking is plenty, others skip the soak and go straight to the cooking stage. Some even add the water and grain together and pop it straight into the pressure cooker.

Step 3 - Filling the jars

Once your grain has dried off, start filling your jars. You want to leave enough space so that you can shake the jars and break the grain apart.

The most important part is the lid, you'll want specially made grain spawn lids. The have a self healing injection port and a filter sicker for air flow.

These lids can be purchased or easily made. Check out how here: article.

Once the jar has been filled and the lid added, it's ready for the pressure cooker.

Step 4 - Steralization

Steralizing the jars is a crucial step toward ensuring a successful colinization. Without this step you will likely have growth from contaminants in the air or grain that will compete with your mycellium.

The most common approach is putting your jars in a pressure cooker/canner or autoclave. Many people already have pressure cookers making this a popular option. They are not typically very large and won't hold very many or very large jars.

Pressure canners are another great option. They are relatively cheap and typically have a much larger volume.

It's generally recommended 60-90 minutes if your device goes to 15 psi. Many pressure cookers only go to 10 or 12 and may need 120-150 mins. The rate of contamination is pretty low and for the home grower, 90 minutes usually suffices.

You'll want to cover your jar/wrap the top with aluminum foil to keep water from pooling on top of the filter.

Step 5 - Innoculate

The easiest approach is to buy spore syringes from a reuptable source. You'll want to shake the syringe vigorously and then pierce the self-healing injection port with the syringe. Next, you'll want to inject 10-20 ml of spore solution. Ideally, you don't need very much because your jars are sterile and the spores don't have any contamination. Extra spore solution increases the spore load and may decrease the innoculation time, but only marginally.

Pull your syringe out and now all you need to do is wait!

Step 6 - Wait.. er Colinization!

Now your jars mostly need to sit. A dark place is generally recommended, but most will grow whever they are. Check the guide on the type of mushroom you're growing to learn what temperature they should colinize at. Typically the range is between 70-85 for colinzation.

Anywhere between 1-3 weeks and you should have a fully colonized jar. The jar should be pretty solid with mycellium and be difficult to see the grain. If there's any doubt, just wait longer - you want the mycellium to be as strong as possible before moving to your bulk container.

The jars can sit for a couple of months and still be viable. If you want to store them longer they can last up to a year in a refrigerator.

Final notes

Congrats on making your first spawn jars. There are tons of variations to this process, but the general structure is the same. Fill jars with some kind of hydrated grain, and put a special lid on. Steralize, innoculate, and be patient.

Next, you'll be utilizing that spawn jar for the final phase of growing mushrooms! Check that out here: