The Pinbloomblog → working-mycology notes from a working mycologist.

The monotub went together on a Tuesday morning: a 60 L tote, four 6 cm holes drilled across the long sides, micropore tape over each, and a 4 cm casing layer of hydrated coir that I pasteurised the night before. Bulk substrate was hardwood pellets at a 1:1.5 spawn ratio; mycelium fully colonised the bag in eleven days before I broke it up and spawned.

Day one through four, the tub sat in darkness at 20°C with the lid closed — the spawn was still locking back into the casing and any FAE would have dried the pins before they set. Day five I started fanning twice a day and misted the chamber walls (never the surface) to bring humidity to ~92% RH. The first primordia showed as small white nodules on day eight, exactly where the casing had knitted tightest.

Contamination showed up on day ten as a small green patch in one corner. I cut it out with a sterile spoon, dusted the cavity with a thin layer of dry coir, and bumped FAE to four fans per day for 48 hours. The patch did not return — the casing sealed back over the wound within a day, and the surrounding pins kept pushing.

Day fourteen was the day the spines started to elongate. I held humidity at 90%, kept temperature at 17°C overnight and 20°C in the day (a 3°C swing that seems to keep the surface dry enough to discourage overlay), and resisted the urge to mist directly. The cluster grew as one dense pom by day seventeen.

I harvested by tearing at the base once the longest spines reached 1 cm, which is the rule we follow across every Lion’s Mane block in the lab — a wait-and-cut past that point turns the spines into yellowing threads and the flavour drops flat. The cluster weighed 240 g, clean smell, even colour, no bruising on the underside.

The takeaway: humidity and FAE set the timeline, patience decides the quality. The block that smells chalky and looks even on day seventeen is the one that went through fourteen days of restraint, not seven. If you want a strain that rewards slow attention, start with Lion’s Mane — the monotub rig above is the cleanest path we have found.

The lab protocol set up two parallel trials across eight quart jars. Trial A used the standard brown-rice recipe we have been running for a season: 75 g rice, 100 mL nutrient solution (1% peptone, 2% glucose), pressure-cooked 90 min at 15 psi. Trial B swapped the brown rice for a 50/50 blend of brown rice and millet, the hypothesis being that smaller grain gives more nucleation points and faster colonisation.

Each jar received a 2 mL liquid-culture inoculation from the same mother plate, sealed in front of a laminar flow hood, and incubated in darkness at 18°C until the mycelium covered the grain surface — eight days for Trial B, ten for Trial A. The millet blend colonised noticeably faster and produced a denser stroma, which matters because Cordyceps primordia form on the stroma, not on the grain itself.

Light cycles were the variable. Each trial split into three jars: one held in darkness, one on a 12/12 photoperiod under a 6500K LED at 800 lux, and one on a 16/8 photoperiod at the same intensity. Pins appeared first on the 12/12 jars — day 21 for Trial B, day 24 for Trial A — and the dark jars never pinned inside the 28-day window.

The 16/8 jars pinned two to three days later than the 12/12 jars, which suggests the longer photoperiod delayed the trigger but did not block it. Across both trials the millet blend outperformed on every metric we measured: faster colonisation, earlier pinning, denser primordia, and a tighter harvest window. We are keeping the millet blend as our standard recipe going forward.

Harvest at peak orange was day 32 for the 12/12 millet jars. We pulled the whole cluster at the substrate line, dried at 40°C overnight, and weighed the dried material. The millet blend yielded 18% more dried fruit body than the brown-rice-only jars at the same light cycle — meaningful enough that we have rebuilt the production protocol around it.

Light is the trigger, substrate is the yield. If you are working with Cordyceps militaris, hold the jars in 12-hour photoperiod after full colonisation and you will see primordia inside three weeks; skip the light and you will wait forever. The strain notes page below documents the recipe we now ship.

Two questions come up every week in the customer inbox: how long will a bag of colonised grain keep, and should it go in the fridge? The short answer is yes — a cold shock extends viable storage from roughly two weeks at room temperature to six weeks cold — but the longer answer depends on species and on what you plan to do with the bag next.

The cold-shock protocol we use is simple. Colonise the bag at room temperature to 100% coverage, then move it directly into a refrigerator at 4°C for a minimum of 12 hours. The cold sends the mycelium into a dormant state and pauses any continued growth that would otherwise consume the grain and starve the bag before use. Bags held cold store cleanly for six weeks; bags held at room temperature should be used within fourteen days.

Watch for the warning signs. A cold bag that develops condensation on the inside of the filter when warmed to room temperature is healthy; a bag that smells sour or shows any liquid pooling at the base is past the point of return. Rye holds cold storage longer than millet — the smaller grain dries out faster when warmed, so plan to use millet bags first.

Spawn-to-substrate ratio depends on which path you took. A fresh bag straight from colonisation wants a 1:1.5 ratio (spawn:substrate by weight) because the mycelium is at full vigour. A bag that has been cold-stored for four weeks or more wants a 1:1 ratio — the mycelium takes longer to recover and a higher spawn percentage buffers that lag.

Rotation cadence in our lab is weekly: incoming spawn bags get a date stamp and a species tag, oldest bags move to the front of the rack, and any bag older than six weeks goes to a monotub rather than a block (the bulk substrate forgives a weaker spawn, the block does not). The result is zero contamination events attributable to spawn storage across the last season.

If you want the cleanest path between an LC syringe and a fruiting block, start with sterilised grain spawn and treat it like a perishable food: date it, rotate it, and cold-shock it the moment colonisation completes. The product page below walks through the supply we ship and what to expect on arrival.