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About Grains[edit | edit source]

What is the difference between grains and the PF tek?

Colonization Time:

The main difference between whole grain and PF style jars is that whole grain remains loose, and can be shaken, thus spreading the mycelium points and colonizing faster.

PF Jars are solid and cannot be shaken; however PF cakes can be used as spawn. If birthed and crumbled or grated they can become inoculation points for a bulk substrate and as such the cakes would be known as spawn. Ideally when using something as spawn it should not be consolidated. as soon as colonization reaches 100% you should use your spawn. When using cakes as cakes you allow them at least a week to consolidate before birthing.


The PF-tek substrate can be sufficiently sterilized even without a pressure cooker, while whole grain virtually requires a pressure cooker to sterilize effectively. It is possible to steam sterilize grain spawn like with the PF tek, but it needs 8 hours of steaming. With a pressure cooker/sterilizer/autoclave at 15psi it only takes 90-120 minutes for a quart jar and upwards of 3 hours for bags.


Grain can be inoculated with with a syringe (liquid culture recommended, not spore), agar wedges, or with more colonized grain, while the PF-jars are limited to a syringe.  To ensure clean spawn, the use of agar is essential.

Bulk Spawn Use:

This bulk substrate is typically 1-10 times the volume of the spawn grain and significantly increases yield per given volume of spawn. PF cakes are primarily a fruiting substrate but can be used as spawn for a bulk substrate, however they are not as effective as grain spawn.

How can I tell if my spawn is fully colonized?

Once all the grains are visibly covered with white mycelium, then the jar can be considered done. You can leave it to colonize a few more days to go sure.

What's the best way to prepare grain spawn?

The 3 most important aspects of grain preparation are to achieve an uniform, correct water content, to kill all contaminants and to get a shakeable substrate.

Choose a tek best suited for your choice of grain and follow it to a T.

Which kind of grain can I use?

You can use almost any grain as long as it's in it's whole form. Check the bottom of this page for detail on different types of grain.

When can I shake grain jars?

In general you want around 30% colonization before your first shake.

What is grain to grain and how is it done?

Grain to grain is a simple method of expanding grain spawn, it is done by using a colonized jar of grains and pouring that one jar into more jars of sterilized uninoculated jars of grain. 1qt is usually expanded into 10qts.

Rye[edit | edit source]

Rye grain can be prepared in the following manner:

  1. Rinse your grain. Fill a bucket with your rye and water, and either pour off the top, or into a bucket with holes drilled in the bottom. Repeat until your water runs clear.
  2. Soak in hot tap water for 4-24 hours, as hot as you can get. Beyond 24 hours is reaching into fermentation, which we do not want. Shorter soaks may perform better in grain bags, where we want a slightly drier prep due to the longer PC cycle.
  3. Add your soaked grain and cold water to a saucepan, or your pressure cooker if you are preparing a large amount. Lining your pressure cooker with a polyester brew bag makes removing the grains easier, and aids in drying. You can add a small amount of gypsum to your grains to help prevent clumping, though this is more of an issue when using bags versus jars.
  4. Add your saucepan or PC to the stove, and turn heat on high. The boiling time will vary dependant on the pot size. With a 23qt presto filled 1/2-3/4 with grain, and water a couple of inches from the top, heat can be killed after around 30 minutes. In a saucepan, it may be around 10 minutes. It will vary, but keep an eye on your grains whilst boiling - if you notice a couple of burst grains, time to kill the heat.
  5. While still boiling, carefully pour your contents directly into a strainer if using a saucepan. If using a PC lined with a brew bag, be extremely careful not to drop the bag back into the water. Having a bucket by the oven helps, lifting the bag over the bucket to catch the draining water and transporting to your drying location.
  6. After straining, you can lay grains out flat on a surface, or a drying rack if you have one. With a polyester brew bag, you can spread the bag out as wide as possible and dry directly in the bag. Drying overnight is a safe option, though not entirely necessary, use paper towel to see if your grains are dry on the outside.
  7. Load into your jars or bags, and pressure cook for 1.5-2 hours. See the Sterilization page for more information.

Wheat[edit | edit source]

Oats[edit | edit source]

Millet[edit | edit source]

Millet can be prepared in the following manner:

  1. Soak millet for 18 hours in cold water.
  2. Drain for 20 minutes or so, after a quick drain the millet is still pretty wet to the touch.
  3. Load into jars or bags and pressure cook. (2-2.5 hours for jars, 3.5-4 hours for bags)

The reason that millet (WBS, etc) can be loaded wet is because they're small, hard seeds, any excess surface moisture is going to be absorbed either during the cycle or within the first few days after inoculation; Seeds haven't had water already boiled into them in the same way that larger grains like wheat, rye, or oats do, This will happen in the pressure cooker.

Don't be concerned if your seed comes out of the PC damp, your jars/bags will sort themselves out by absorbing the excess moisture. Jars soak up moisture in a few days, bags are good to go after a good shake.

Wild Bird Seed[edit | edit source]