How to Store Your Cultures

Whether you're holding onto a favorite genetic for a few weeks or archiving it for years, how you store your cultures matters just as much as how you isolate them. Here's a rundown of the three most common storage formats and how to keep each one viable for as long as possible.

Liquid Culture (LC)

Short-Term (weeks to a few months):

• store at room temperature, out of direct light.
• keep syringes capped tightly (luer cap on) to prevent contamination and evaporation.
• Give it a swirl every couple of weeks to keep mycelium suspended and aerated.
• use within 2-3 months for best vigor as LC degrades faster than other storage methods.

Long-Term (6+ months):

• refrigerate at 34-38°F (1-3°C). This slows metabolic activity significantly.
• avoid freezing. Ice crystals will rupture cell walls and kill the culture.
• store syringes the same direction consistently (needle-down helps prevent any settled mycelium from clogging the tip).
• check periodically for contamination (discoloration, off smells, unusual textures) and watch for the plunger drying out or sticking.
• LC isn't a great long-term archival format. 6-12 months refrigerated is a safe estimate, but after a year viability starts to drop. I have successfully used 3-year-old LC, but not at a very high rate. For anything you want to keep for years, use tubes/slants.

Agar Plates

Short-Term (2-3 months):

• store sealed (parafilm or tape around the edge) at room temperature in a dark space.
• stack petri dishes upside-down (agar side up) to prevent condensation from dripping onto the mycelium.
• fine for active use — pulling wedges for transfers, LC inoculation, etc.

Long-Term (not recommended past a few months):

• plates dry out and are prone to contamination issues over time.
• if you must hold a plate longer, refrigeration (34-38°F) can extend viability to 4-6 months, but growth will slow and eventually stall.
• plates are best treated as a working/transfer format, not an archive.

Slants/Castellani Tubes

This is your best long-term storage option — designed specifically for it. My preferred method is Castellani tubes as opposed to slants, but that’s a topic for another day.

Long-Term (1-5+ years):

• refrigerate in sterile water at around 36°F.
• reduced surface-area-to-volume ratio in a tube (vs. a plate) slows dehydration and degradation dramatically.
• label with strain, date, and filial generation…you'll thank yourself later (ask me how I know).
• re-culture and refresh (transfer to a new tube or slant) every 2 years even in cold storage as a hedge against contamination and senescence.

Golden rule: never freeze any live culture and always keep at least two backups of any genetic you care about, ideally in two different formats.