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Storing mushroom plugs correctly is all about keeping the mycelium alive and vigorous until you’re ready to inoculate your logs or stumps.
If you’ve just received a shipment of plugs or you’re planning to use them over several weekends, you need to know how to store mushroom plugs to maintain their viability.
The short answer is that you’ll want to mimic the cool, humid conditions of a forest floor, and you’ll need to balance airflow with moisture retention.
In this post, we’ll break down the best methods for short-term and long-term storage, what temperature and humidity levels to aim for, and common pitfalls that can ruin your plugs.
Let’s dig into the details so your hard work pays off with a bountiful flush of mushrooms.
Why Proper Mushroom Plug Storage Matters
Proper mushroom plug storage matters because it directly impacts the success rate of your inoculation project.
Mushroom plugs are essentially little dowels infused with living mycelium, which is the vegetative part of the fungus.
If you don’t store mushroom plugs correctly, the mycelium can dry out, overheat, or become contaminated.
A dried-out plug is dead, and a dead plug will never produce mushrooms.
Similarly, if the plugs get too warm, the mycelium may become stressed and lose its vigor.
When you properly store mushroom plugs, you’re essentially putting the mycelium into a state of dormancy, like hibernation.
This allows you to delay inoculation for weeks or even months without sacrificing quality.
Understanding these basic principles will save you from wasting money and time on a failed growing attempt.
1. Temperature Is the Most Critical Factor
The absolute most critical factor in how to store mushroom plugs is temperature.
You want to keep the plugs cold, ideally between 33°F and 40°F (1°C to 4°C).
This is the temperature range of a standard refrigerator, which is perfect for slowing down the mycelium’s metabolism.
If you can store mushroom plugs in a fridge, you’ll keep them dormant and healthy for several months.
Avoid storing plugs in a freezer, as freezing can cause ice crystals to form and rupture the delicate mycelial cells.
A consistent, cold temperature is your best defense against premature aging and contamination.
2. Maintain Optimal Humidity Levels
Maintaining the right humidity is the second pillar of proper mushroom plug storage.
The plugs themselves should feel slightly moist but not soaking wet or bone dry.
Most commercially produced plugs come in a plastic bag with a filter patch, which helps regulate gas exchange.
If you’re storing them in this original packaging, you generally don’t need to add any extra moisture for the first few weeks.
However, if the plugs look dry or the bag has lost moisture, you can add a tiny bit of sterile water or mist the inside of the bag.
Just be careful, too much moisture can lead to bacterial growth or mold, which is the enemy of your mycelium.
How to Store Mushroom Plugs In the Refrigerator
How to store mushroom plugs in the refrigerator is the most common question we get, and the process is pretty straightforward.
The fridge is your best friend for short-term and medium-term storage, and it’s the method we recommend for most home growers.
The key is to use the crisper drawer, which tends to have more stable humidity than the main compartment.
You’ll also want to keep them away from ripening fruits, as these release ethylene gas which can negatively affect mycelium.
Here’s how to do it step by step.
1. Keep Them in Their Original Breathable Bag
The best way to store mushroom plugs for most people is to keep them in the bag they came in.
These bags are specifically designed with a microporous filter that allows for oxygen exchange while preventing contaminants from getting in.
If you’ve already opened the bag, simply press out the excess air and seal it tightly.
You can use a clip or a rubber band to close it securely.
Keeping them in this bag provides the ideal balance of humidity and airflow that we discussed earlier.
2. Use a Secondary Container for Extra Protection
For long-term storage, it’s a good idea to place the original bag inside a larger, airtight container.
This could be a Tupperware box or a large Ziploc bag.
This secondary container protects the plugs from any temperature fluctuations when you open the fridge door.
It also protects them from absorbing any odors from other food in your fridge.
Just make sure not to seal the inner bag completely airtight if it doesn’t have a filter patch.
If you’re using a homemade bag without a filter, you’ll need to “burp” the bag every couple of weeks to let in fresh oxygen and release any CO2 buildup.
3. Label and Date Your Plugs
It’s easy to forget which strain of oyster or shiitake you have sitting in the fridge.
So, always label the bag with the mushroom species and the date you received or stored them.
This simple habit helps you track the age of your plugs and ensures you use the oldest ones first.
While you can store mushroom plugs for up to six months in the fridge, it’s best to use them within three months for optimal vigor.
The longer they sit, the more energy the mycelium uses, and the slower they’ll colonize your logs.
Proper Storage Without Refrigeration
Proper storage without refrigeration is a bit trickier, but it’s possible for very short periods.
If you don’t have access to a fridge, you can still store mushroom plugs for a few days to a week.
The goal is to find a cool, dark, and well-ventilated spot in your home.
A basement, a root cellar, or a cool closet are all good options.
The critical thing is to keep the temperature as low as possible, ideally below 60°F (15°C).
This is why it’s best to plan your inoculation project so you can use the plugs soon after receiving them if you can’t refrigerate them.
1. Avoid Direct Sunlight and Heat Sources
UV rays from the sun can damage the mycelium, and heat will cause it to dry out rapidly.
Keep your plug bag away from windows, radiators, stoves, and other heat-generating appliances.
Place the bag in a cardboard box to add an extra layer of insulation and darkness.
This simple method can keep plugs viable for about a week, depending on your ambient room temperature.
2. Check and Rehydrate as Needed
In a warm, dry environment, the plugs are more likely to lose moisture.
You’ll need to check on them every few days to ensure the wood dowels haven’t dried out.
If they feel squeaky or look lighter in color, they are too dry.
To rehydrate, you can mist the inside of the bag with a spray bottle filled with distilled water.
Don’t soak the plugs, just moisten the surface and the paper bag or packing material inside.
This should perk them up for another few days until you’re ready to use them.
Common Mistakes to Avoid When Storing Mushroom Plugs
Avoiding common mistakes is just as important as knowing the correct steps.
Even with the best intentions, a small error can compromise your entire batch of plugs.
We see a few recurring issues with new growers that are easy to prevent.
Let’s make sure you don’t fall into these traps.
1. Storing Them in an Airtight Container Without Air
Mycelium needs oxygen to survive, just like we do.
If you store mushroom plugs in a sealed Mason jar with no airflow, the mycelium will suffocate.
It will consume the available oxygen and then produce carbon dioxide, which will eventually kill it.
If you must use an airtight container, make sure you open it daily to let in fresh air.
Or, better yet, use a container with a filter patch or just poke a few tiny holes in the lid and cover them with micropore tape.
2. Letting Them Freeze
We touched on this earlier, but it’s worth repeating: do not freeze your mushroom plugs.
While some growers have had success storing certain species in a freezer, it’s too risky for most.
The expansion of water during freezing can rupture the cell walls of the mycelium.
This leads to a watery, dead mess when the plugs thaw.
Unless you have specific guidance for your particular mushroom species, stick to the fridge, not the freezer.
3. Waiting Too Long to Use Them
Even with perfect storage, mycelium loses vitality over time.
A fresh plug will colonize a log much faster than a six-month-old plug.
For the best results, plan your storage to be as short as possible.
Try to inoculate your logs within a month of receiving your plugs.
If you’ve stored mushroom plugs for several months, expect a slower, less vigorous colonization rate.
So, How Should You Store Mushroom Plugs?
So, how should you store mushroom plugs to get the best results?
You should store mushroom plugs in their original breathable bag inside your refrigerator’s crisper drawer, which will keep the mycelium dormant for several months.
Remember to keep them cold, dark, and slightly moist, and always avoid freezing them.
Whether you’re storing them for a few days or a few months, these methods will keep your mycelium healthy and ready to grow.
Happy growing, and enjoy the fruits of your labor.