How to Do a Grain-to-Grain Transfer (G2G) – Multiply Your Grow Easily

When I first got into growing mushrooms, a couple things instantly hooked me — flushes and grain-to-grain transfers. Coming from growing plants and microgreens, I was blown away by how easy mushrooms make it to multiply your grow.

With plants, you usually have to start from seed again. With mushrooms?
If you have one clean jar of colonized grain, you can easily turn it into five or more with a simple grain-to-grain transfer (G2G). It felt like unlocking a cheat code — same genetics, faster colonization, and a huge jump in production for almost no extra cost.

In this post, I’ll walk you through how I personally do G2G, the gear you need, tips I’ve learned, and a few things to avoid (including one issue I ran into early on with jars that were too compact to break up).

What Is Grain-to-Grain Transfer?

A grain-to-grain transfer (often called “G2G”) is when you take colonized grain from one jar and transfer it into new, sterile jars of uncolonized grain.

Your fully-colonized jar acts as the mother jar.

Why it's so effective:

• You’re expanding the exact same genetics

• Colonization is MUCH faster

• You skip spores and liquid culture

• You take one jar and turn it into many

If you’re looking to scale your grow or just get more out of each culture, G2G is one of the best methods.

Why I Loved G2G When I Started

The thing that fascinated me early on was how easy it was to multiply your grow without needing fancy tech.

I remember being used to microgreens where you start over every tray. So when I realized:

“Wait… one jar can become five jars?”

My mind was blown.

Mushrooms feel like they have built-in “expansion moves,” and G2G is one of the most efficient.

What You Need

Here’s what I personally use:

• A still-air box (SAB) or a flow hood

• Alcohol wipes / 70% iso

• Sterile grain jars

• A fully colonized mother jar

• Flame sterilizer (for tools)

• Gloves + mask

• A small spoon optional

• A jar scraper or mason jar ring optional

Step-by-Step: How I Do Grain-to-Grain Transfers

1. Prep Your Workspace

Wipe down your SAB or flow hood.
Wipe down jars, gloves, tools — keep everything clean.

Good prep = fewer headaches.

2. Break Up Your Mother Jar

This is where personal experience matters.

Sometimes jars are super easy to break up.
Other strains?
If you let them go too long, they get dense, almost like a brick.

Here’s what’s worked for me:

• Smacking the bottom of the jar with your palm

• Rolling the jar on a towel

• Using a mason jar screw ring as a “knuckle guard” to hit it harder

• And yes — using a sterile metal spoon inside the SAB actually does work

If the jar is too compact, using a spoon is 100% a legit method as long as:

• You sterilize the spoon

• Only open the jar inside the SAB

• Keep movements slow and controlled

Just don’t scrape the grains aggressively — you’re just loosening them.

3. Open Your Jars in the SAB

Once your grains are broken up, open your jars one at a time inside the SAB.

Keep your hands steady.
Keep the jars as still as possible.
Angle the openings away from each other.

4. Transfer the Grain

Use the “tap and pour” method:

• Tilt your mother jar

• Let a spoonful of colonized grain fall into each new jar

• Close each jar immediately

I usually aim for around 1 tablespoon per jar.
Too much isn’t harmful — it’s just unnecessary.

5. Shake the Receiving Jars

Once you’ve added the colonized grain:

• Close the jar

• Shake gently

• Let the grains distribute evenly

This speeds up colonization BIG TIME.

6. Incubate

Place the new jars back on a shelf at room temperature.

You’ll see mycelium jump off the colonized grains fast.
Usually within 24–48 hours.

Most jars finish in 5–10 days depending on temperature and genetics.

Tips I Learned the Hard Way

Here are some things I wish I knew earlier:

Tip 1: Don’t let your mother jar over-colonize

If you wait too long, the jar gets compact and hard to break up.

G2G works best when:

• 100% colonized

• But still fluffy and easy to shake

Tip 2: Spoon method is legit

If you need a spoon, use it.
I’ve seen growers call it “sketchy,” but honestly — it works fine if:

• You flame sterilize

• You work in a SAB

• You move slow

Tip 3: Only use CLEAN jars

If the mother jar is slightly contaminated, G2G will multiply that contamination into every new jar.

It’s like cloning the good and the bad.

Tip 4: Shake too early = stalled jar

Let the mycelium grab onto the new grain for a day or two before shaking aggressively.

Why G2G Is Worth It

Grain-to-grain transfers are one of the easiest ways to:

• Expand your operation

• Save money

• Speed up colonization

• Multiply a clean culture

• Grow more mushrooms using the same genetics

If you’re looking to scale your grow or just get more out of your jars, this is one of the most important skills you can learn early on.

Final Thoughts

Honestly, G2G was one of the things that pulled me deeper into mushroom growing.
The fact you can take one clean jar and turn it into five or more — all with the same strain, same genetics, and super fast colonization — just felt like magic the first time I did it.

Once you get comfortable doing them in a SAB, it becomes second nature.