Can you really grow mushrooms from an off the shelf Uncle Ben’s Ready Rice package?

According to many online cultivation forums, not only can you, but it’s even easier than you think.

Spawning mycelium to a store-bought rice bag?

… sounds too good to be true. And if it is true, what will we do with all of the time saved preparing grain, packing jars and pressure cooking???


Let the learning begin. 


According to various mushroom cultivation forums online, the basic process for cultivating mushrooms using Ready Rice is:

  • Purchase Uncle Ben’s Ready Rice from your local grocer
  • Prep surfaces and utensils
  • Cut a small hole in the prepared bag
  • Inject 1CC of spore solution from the spore syringe of the variety of your choice
  • Cover the slit with micropore tape to allow airflow
  • Set aside in a dark place inspecting the bags after 5-7 days for mycelium growth and/or contamination
  • Break up the mycelium chunks to spread mycelium covered grain evenly throughout the bag and return the bags to the dark spawning area
  • Once the bag is fully colonized (12-30 days) you may either place into fruiting condition or prepare your spawn for a bulk grow

Although contamination was a worry of ours, we thought this tek was too good to pass up. And so we give it a go.


This is our process post and will be updating it along our journey.

What you will need: 

  • Uncle Ben’s Ready Rice – Plain brown or white rice (no flavor added)
  • Spore Syringe
  • Xacto knife
  • Rubbing alcohol
  • Lighter
  • Latex gloves
  • Micropore tape
  • Paper towels

Day 1

Our first step is to prep our working surfaces and wiping down all bags and utensils with rubbing alcohol. This is an important practice in the inoculation process which will reduce the chances of contamination.

A best practice is to perform the inoculation process in front of a flow hood or in a still air box. But for this tek we wanted to see if we can accomplish good results on a budget.

Step two is to sterilize our knife and cut into our Uncle Ben’s rice package.

Wipe down your bag with rubbing alcohol and make a small slit in the corner or center of the bag. Try not to make it too large of a hole or you may lose too much moisture during the spawning process. 

Once we’ve cut our hole, we will then sterilize our spore syringe and inject our spores.


  1. Hold the tip of your syringe over a flame until it is red hot. Allow to cool and wipe off using an alcohol-soaked paper towel.
  2. Insert your syringe into the hole you cut and inject 1-2cc’s of spore solution. Try to distribute the solution around the bag by moving your needle around. 

Lastly, we cover our hole with micropore tape and set the bag aside. 


Repeat this process making sure to wipe down all utensils, bags, and flame sterilize your needle and knife with every bag.

Then find a dark and warm place to set your bags to colonize. The ideal temperature is around 78° F.

Check your bags every couple of days for signs of contamination.

A contaminated bag may show signs of mold or put off a foul smell. 

After 5 to 7 days you should see mycelium beginning to form through the clear window at the bottom of the bag.

That is all for this post. Check back in the next couple of days for an update on this project!

UPDATE: Day 13

At this point we will be preparing to introduce in to fruiting conditions.

We pulled out our bags to check on their progress and found that they were roughly 80% colonized!

While only a little bit of mycelium is visible from the window at the bottom of the bag, the bags feel dense which indicates that the mycelium network has taken hold of the rice. Additionally, the bags smell wonderful! No signs of contamination!

Now its time to massage the bags to break up the mycelium chunk to evenly distribute and help speed up the colonization.

Based on the rate of our colonization, we could have done this around day 10. Almost time to put into fruiting! Stay tuned.

we will now beUPDATE: Day 19

The recent Covid madness has had us all pretty pre-occupied, so our bags were sitting longer than we would have liked. However, today we opened our bags to check progress and get ready for fruiting!

As you can see, the Uncle Ben’s rice bags are now fully colonized and have a wonderful mushroom smell to them.

We will be testing two methods to fruit these mushrooms. The first is a bulk colonization technique using a simple coco choir substrate. And for the second we will be fruiting directly from the Uncle Ben’s rice bag.

Bulk Cultivation

For our bulk grow we added a liner (black trashbag) to our fruiting chamber and then layered the substrate and colonized rice. A top substrate layer was used to cover the exposed rice. We then cut back the trash bag and closed the container.

In this tutorial, we will be using a beginner-friendly simple coco coir substrate recipe – adopted from Bods Bucket Tek.


Edit: For our fruiting chamber we used a 56 quart Sterilite container with 1.5 inch holes drilled about 5 inches up on the sides (2), then one 1.5 inch hole on either end, near the top of the container. These holes were then lightly stuffed with polyfil.

Day 21

Our spawn has taken to our coir substrate nicely. A week or so longer until we should see some pins!

Day 27

And we have mushrooms folks!

Looks like Uncle Ben’s Ready Rice is an off the shelf alternative to the traditional spawn prep methods. Out of the 10 bags we used, all produced white, fluffy, and healthy mycelium growth, with no signs of contamination. 

We will continue to update the blog with our progress photos. But so far it seems that old Uncle Ben has not let us down.  

Fruiting directly from the bag.

To produce fruits directly from the bag we first re-hydrated the cake by filling the bag up with distilled water and allowing the cake for absorb moisture for 12 hours.

Then we created our fruiting chamber using a 23-L Sterilite tub and utilized moistened perlite and ventilation whole stuffed with polyfill.

Our goal here is to keep optimal conditions between airflow, temperature and humidity for our mushrooms to flourish.

Day 5

After 5 days in the fruiting chamber you can see the mycelium has turned to a fluffy white and should begin fruiting any day now. 

Setback After Setback

Just prior to the Covid pandemic, this tub was transported to another location. Consequently, during this time the bag was kept in sub-optimal conditions and neglected, which halted its progress. This set us back about twenty days and required some delicate care to bring it back to life. 


Nursing our Uncle Ben’s bag to good health has finally paid off!

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