How to Cultivate Black Fungus at Home

So the purpose of growing Black Fungus is to:

• Establish a healthy companion culture on hardwood substrate.
• Combine a small amount of it with a much larger amount of Snow Fungus culture.
• Use the completed dual culture to produce Snow Fungus fruiting bodies.

Commercial and research systems use both organisms together because A. archeri strongly stimulates Snow Fungus mycelial development and fruiting.

Black Fungus grows on woody material and should be cultivated on a sterilized sawdust-based substrate. For most home growers we recommend hardwood sawdust or hardwood fuel pellets, rice bran or wheat bran, gypsum, filter-patch bags or filtered cultivation bottles, and your Black Fungus liquid culture. Unlike many gourmet mushrooms, there's little benefit to running this culture through several large grain bags first — it can be inoculated directly into properly prepared hardwood substrate.

Research-tested substrate formula

78% sawdust · 20% rice/wheat bran · 1% gypsum or ag lime · 1% sucrose · ~60% total moisture. (Used for mixed T. fuciformis + A. archeri cultivation.)

Simpler home formula

8 parts hardwood sawdust : 2 parts wheat/rice bran + a small amount of gypsum, with enough water to reach ~60–65% moisture. The substrate should feel evenly hydrated but release no more than a few drops when squeezed firmly.

Pro Tip

• Use fine hardwood sawdust or hydrated hardwood fuel pellets — not fresh aromatic softwood.
• Don't use ordinary potting soil, manure compost, coco coir, or an unsupplemented grain-only substrate as the final medium.
• Black Fungus is vigorous, but the bran-rich substrate also attracts molds and bacteria — proper sterilization is essential.
• Bottles are handy for small companion-spawn batches: you can watch the culture without opening the container.

Pro Tip

• Never inject liquid culture into warm substrate — letting containers cool overnight is safest.
• Avoid packing the substrate extremely tightly; Black Fungus benefits from an evenly hydrated but aerated medium.
• Using a premade sterilized hardwood bag? Follow the substrate manufacturer's inoculation instructions.

Coverage & caution

One 10 cc syringe generally inoculates two larger companion-spawn containers (~5 cc each) or several smaller experimental bottles (~2–3 cc each).

More liquid culture doesn't necessarily mean faster growth — excess liquid can create wet pockets that encourage bacterial contamination.

Keep the inoculated substrate at:

• Temperature: 72–75°F (acceptable ~68–77°F)
• Light: darkness or normal indirect room light
• External humidity: not critical while the container stays sealed
• Fresh air: filtered gas exchange only
• Expected colonization: ~2–4 weeks

In mixed-culture research the sawdust-and-bran substrate was incubated at 22–24°C (72–75°F) until the mycelium filled the container.

Healthy A. archeri may appear:

• White when growth first begins
• Pale gray as the colony develops
• Grayish or light gray-brown when mature
• Fine and spreading at the leading edge; denser and more consolidated with age

Gray is normal here. Research describes A. archeri cultures as grayish, while Snow Fungus cultures are more distinctly whitish. Don't expect a bright-white oyster-style block — gray coloration can be perfectly normal for this species.

A gentle break and shake can be done once if you're expanding the culture by itself. Wait until roughly 30–40% of the substrate shows healthy growth, then gently break apart the colonized areas, distribute them through the container, return it to 72–75°F, and leave it undisturbed until fully colonized.

Don't repeatedly shake the container — excessive disturbance slows recovery and makes contamination harder to spot. And once Black Fungus has been combined with Snow Fungus, avoid aggressive break-and-shake cycles: keeping the correct balance between the two organisms matters more than forcefully distributing them like ordinary grain spawn.

The companion spawn is ready when:

• Growth has spread throughout the substrate.
• No uncolonized wet pockets remain.
• The substrate appears firmly held together.
• The culture has recovered fully from any mixing.
• There are no green, black, pink, or brightly colored contaminant colonies.
• There's no sour smell or excessive liquid accumulation.

The most important part of this whole process: maintain a much larger proportion of Snow Fungus than Black Fungus. A. archeri grows considerably faster than T. fuciformis, so equal amounts can let the Black Fungus dominate the container before the Snow Fungus establishes.

Do NOT use a 50:50 mixture.

Published methods established Snow Fungus first (until its colony reached ~1–2 cm), then added only ~0.1–1% Black Fungus hyphae — or used a liquid-culture ratio of about 95% Snow Fungus : 5% Black Fungus. Successful fruiting was reported with the 95:5 liquid ratio.

Practical starting ratio (per 10 cc combined inoculum)

Precise: 9.5 cc Snow Fungus + 0.5 cc Black Fungus.
Easier home measure: 9 cc Snow Fungus + 1 cc Black Fungus.

Note: the 9:1 measure contains more Black Fungus than the published 95:5 — so watch carefully for overly rapid gray companion growth and adjust toward 95:5 if it races ahead.

Pro Tip

• Shake each culture syringe separately before measuring.
• Use separate sterile needles whenever possible.
• Don't inject one used needle directly into the other culture syringe.
• Combining on agar first gives more control, but direct substrate inoculation is more practical for many home growers.
• The ideal ratio varies by culture vigor — the published figure is a starting point, not a guarantee.

Method 1 — Combine Before Inoculation

Measure ~95% Snow Fungus + ~5% Black Fungus, inoculate into a small sterilized sawdust-and-bran bottle, and incubate at 72–75°F. Watch for interaction between the white Snow Fungus growth and grayish Black Fungus growth. Allow the combined spawn to establish for ~10–14 days before transferring into production substrate.

Research comparing spawn ages found 10–14 days outperformed younger or older spawn, with the 14-day culture giving the highest average fresh and dry yield.

Method 2 — Establish Snow Fungus First

Inoculate the substrate or agar with Snow Fungus, let its colony begin developing, then introduce a very small quantity of Black Fungus at a separate point and let the organisms grow toward one another. Transfer the successful combined culture into the final production substrate. This gives the slower Snow Fungus a head start and reduces the chance that Black Fungus immediately dominates.

What a healthy dual culture looks like

Fine white Snow Fungus growth, grayish Black Fungus mycelium, increasingly dense white areas where they interact, small white mycelial globules near the surface, and limited yellowish-brown exudate. White globules and yellowish-brown exudate were reported as important indicators preceding Snow Fungus primordium formation. A little amber/yellow-brown liquid is normal; large pools should be drained or corrected before they saturate the culture.

Production substrate (same approximate formula)

78 parts sawdust · 20 parts rice/wheat bran · 1 part gypsum or lime · 1 part sucrose · ~60–65% moisture.

Black Fungus by itself isn't normally cultivated for a conventional flush — there's no reliable home method for producing standalone A. archeri stromata. Its value here is the vigorous mycelium it develops in the substrate and the nutritional support it gives Snow Fungus.

The visible fruiting bodies from the completed dual culture are the white, translucent, jelly-like structures of Tremella fuciformis — not a typical Black Fungus mushroom. For that reason, the full fruiting process is covered in the separate Snow Fungus grow guide.

For the combined culture, research found:

• Primordium formation performed best at 72–75°F.
• White mycelial globules formed before primordia.
• Fruiting development required light, humidity, ventilation, and stable temperature.
• Mature Snow Fungus fruiting bodies formed ~30–40 days after inoculation under the studied conditions.

Mycelium is gray instead of white. Gray or gray-brown can be normal for A. archeri. It should still look organized, even, and firmly associated with the substrate.

It grew much faster than the Snow Fungus. Too much Black Fungus was likely used. Snow Fungus should be the overwhelming majority — begin near 95:5, not equal amounts.

Black Fungus colonized, but no mushrooms formed. Expected when grown alone. Its purpose is companion spawn for Snow Fungus, not a standalone indoor crop.

Heavy yellow or brown liquid in the substrate. A little exudate is normal in dual-culture development. Heavy pooling may mean excess moisture, stress, poor gas exchange, or bacterial contamination.

Green growth appeared. Not a normal stage — isolate and discard the contaminated container without opening it indoors.

Sour or fermented smell. Healthy cultures smell earthy or woody. Sour, sweet-fermented, rotten, or strongly unpleasant odors usually mean bacterial or yeast contamination.

The culture stopped after being shaken. Return it to 72–75°F and leave it undisturbed. Black Fungus usually recovers well, though compacted or overly wet substrate may prevent even regrowth.

Snow Fungus never developed in the mixed container. Possible causes: too much Black Fungus, weak or aged Snow Fungus culture, combining at the wrong stage, excess moisture, temperatures outside range, contamination, or poor interaction between the specific isolates.