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Long term mycelium storage on Agar Slants

Agar slants for long term mycelium storage
Agar slants and tips on mycelium long term storage

Agar Slants and tips on how to store mushroom mycelium for longer

What are agar slants

Most cultivators store their mushroom culture collection long term in test tubes known as Agar Slants.

Agar slants are formed by using sterile agar media in a test tube and setting it at an angle. This allows for more surface area for mycelial growth than if the agar were allowed to solidify vertically.

What agar media to choose for agar slants

One more important note: use low-nutrient media for agar slants (storage agar media), e.g. 1% of nutrients for your choice. It can be any general purpose agar media with 1% of nutrients (no more than 2% of nutrients). For instance Potato Dextrose Agar (PDA), Malt Extract Agar (MEA) or low nutrient Oatmeal agar (OA), Cornmeal Agar (CMA) etc.

🟠 Check out: List of Agar Recipes for mushroom cultivation

What are the benefits of using low-nutrient agar media for mycelium storage:

  1. It slows down mycelium growth, which helps to extend the storage life of the culture.
  2. It preserves the viability of the mycelium for longer periods of time.
  3. When the mycelium is transferred to fresh, more nutrient-rich agar media, it experiences a boost in growth.

Overall, using low-nutrient agar media for long-term storage of mycelium is a good practice that can help to ensure the viability of your cultures.

To inoculate the test tube, cut a small piece of agar culture from your petri dish and place it on top of the agar in the tube. Seal agar slants with parafilm or close the test tube. Let mycelium completely colonize the agar on top for several days.

❗️For inoculation process (agar to agar transfer in this case) use Still Air Box or Laminar Flow Hood! Remember to sterilize the tool you use for agar inoculation (scalpel blade or inoculation needle) before inoculating each test tube!

How and how long to store agar slants

❓Question: I need a way to store mushroom cultures on agar slants long term. Do you think they'd survive long term in a basement, 3ft (~1m) underground? Temperature should remain about 48-50F (9–10°C)

Recommended temperature range for agar slants for long-term storage is 36–41°F (2–5°C) in the refrigerator or cold dark room. I assume 48–50°F (9–10°C) would also work, but the higher the temperature, the more active the mycelium growth and the shorter the storage time will be.

❗️It is essential to reduce the metabolic activity in order to prevent rapid exhaustion of the medium.

Recommended storage time for agar slants is 1 year. Actually they can be stored for several years. The exact storage time will depend on the mushroom species, the nutrient content of the agar media, and the temperature at which the slants are stored. Magic mushroom species such as P. Cubensis, P. Natalensis, sclerotia species P. Tampanensis, P. Mexicana or P. Galindoii can be stored on agar slants successfully for about 2 years. Panaeolus species - for 1-2 years. Some mushroom species, such as Oysters and Shiitake - for up to 3 years. Other mushroom species, such as morels, may only be storable for a few months.

Once I accidentally stored Lion's Mane petri dish in a fridge for 2 years, while recommended storage time is 6-12 month. Agar was wet enough and mycelium survived

It is important to check your agar slants regularly for contamination. If you notice any signs of contamination (discoloration, slime, mold growth), discard the slants immediately.

For newbie cultivators I suggest to prepare at least 5 test tubes of each mushroom culture you'd like to store!

Agar Slants with wooden sticks

Check your test tubes regularly, because the agar and mycelium might dry out, even if the test tubes are sealed/closed tightly.

❗️Drying it out is one more important factor in determining shelf life of agar slants. Check agar slants for condensation from time to time. Condensation means there is a heat source driving out water from the agar, which will dry it out quickly

For additional source of moisture, wooden coffee stirrer sticks soaked in water can be added to the test tubes with agar.

Why is it beneficial? If the agar dries out, these wooden sticks maintain water and save the mycelium further. To revive mycelium you can put the stick on agar and wait for its growth. This method especially beneficial for wood-loving mushroom species and any other species.

How to make agar slants with wooden sticks
How to make agar slants with wooden sticks
Agar slants with wooden sticks
  1. Soak wooden sticks in water for 24 hours or simmer them in water for 30 minutes before adding to test tubs and pouring agar media. Cut them to fit the size of test tubes
  2. Use heat resistant autoclavable 5PP centrifuge test tubes with screw caps, the volume between 15-50 ml.
  3. Add wooden sticks in each test tube.
  4. Pour prepared agar media in each test tube (about 1/2-2/3 of the volume).
  5. Close the lids of test tubes, but not completely tight!
  6. Place test tubes on a wire rack or just cover them all together in aluminium foil.
  7. Sterilize in PC for 30 mins.
  8. Open the PC in 30 minutes after depressurization.
  9. Let the agar to cool down horizontally or setting it at an angle 20-30°.
  10. When agar slants cool down to room temperature they are ready for inoculation.
  11. Inoculate agar slants (agar to agar transfer). Cut the agar piece the size of a grain.
  12. Close the test tubes with plastic lids.
  13. Let them colonize for a few days.
  14. Seal test tubes additionally with lab film (parafilm) to ensure sterility during storage.

    💡 No pour agar and sterilization right in test tubes reduce the risk of contamination

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Agar Slants with mineral oil or liquid paraffin

Never tried this method, but I know mycologists and experienced mushroom cultivators cover the agar slants (after agar colonization) with sterile mineral oil or medical liquid paraffin. Mineral oil or pharmaceutical grade liquid paraffin is cheap and available in any pharmacy.

The entire slope should be covered. Then the culture is stored at low temperature. This creates a protection layer that keeps moisture and protect mycelium in test tubes for up to 3 years.

To use this culture further, just pour out the mineral oil (liquid paraffin). Cut a sample of the culture and inoculate a new fresh agar plate.


Agar slants are a good way to store mushroom mycelium, because they provide a sterile environment and prevent the cultures from drying out for years. This is your backup for any unexpected cases.

Enjoy your home mycology!

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Peace, Shroomok ❤️

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