How to Grow Hexagonal Polypore (Neofavolus americanus)

• 1 lb dry wheat berries or rye berries (per bag)
• Water for soaking and simmering
• 1 polypropylene grain bag with 0.2-micron filter patch
• Pressure cooker capable of 15 PSI

Scale-up: 3 lb dry grain → 3 bags | 5 lb dry grain → 5 bags

Rinse the grain and soak it in clean water for 12 hours. Drain, then simmer in fresh water for 15–20 minutes until kernels are fully swollen and tender but not splitting. Drain thoroughly in a colander and spread on a clean surface until the exteriors feel dry to the touch — moist inside, no surface moisture outside. Load into the grain bag, fold and seal the top tightly with the bag's seal strip or impulse sealer, and sterilize at 15 PSI for 90–120 minutes. Allow grain to cool completely to room temperature before inoculating — warm grain kills liquid culture.

Out-Grow carries sterilized grain spawn bags ready to inoculate if you want to skip this step.

• Hexagonal Polypore liquid culture syringe — 3–5 cc per 1 lb bag
• 70% isopropyl alcohol and clean paper towels
• Still-air box or laminar flow hood
• Cooled, sterilized grain bag from Step 1

Work inside a still-air box or in front of a laminar flow hood. Wipe the injection port of the grain bag with 70% isopropyl alcohol and allow it to dry for 30 seconds. Shake the liquid culture syringe to distribute mycelium evenly, then inject 3–5 cc of Neofavolus americanus liquid culture through the self-healing injection port. Withdraw the needle, wipe the port again, and set the bag upright in your incubation area. Out-Grow sells Hexagonal Polypore (Neofavolus americanus) liquid culture ready to inject: Hexagonal Polypore Neofavolus americanus Liquid Culture.

• Inoculated grain bag from Step 2
• Dark incubation space held at 70–77°F
• Thermometer to confirm temperature

Place the bag in a clean, dark area at 70–77°F. Do not disturb the bag for the first 5–7 days; early agitation disrupts mycelial establishment. After visible white mycelium covers roughly half the bag, gently knead the outside of the bag to break up and redistribute colonized grain — this accelerates even colonization. Continue incubating without opening until grain is fully white throughout. Expect 14–21 days for a 1 lb bag; slower colonization is normal for Neofavolus americanus compared to faster-growing species. Discard any bag showing green, black, or grey patches, a sour smell, or slimy kernels.

• 4 lbs hardwood fuel pellets or hardwood sawdust (oak or mixed hardwood)
• ¾ lb wheat bran
• ¼ lb gypsum
• 5½ cups water (add gradually — substrate is at field capacity when a firm squeeze yields a few drops, not a stream)
• Large polypropylene substrate bag with filter patch
• Pressure cooker at 15 PSI

Scale-up: 3 blocks — multiply all amounts by 3 | 5 blocks — multiply all amounts by 5

If using fuel pellets, combine pellets with water first and allow them to hydrate and break apart completely into fine sawdust before adding bran and gypsum. Mix all dry and wet ingredients thoroughly until evenly blended with no dry pockets. Load into substrate bags and sterilize at 15 PSI for 90–120 minutes. Allow to cool completely before inoculating — never inoculate warm mushroom substrate.

Out-Grow also carries ready-to-use hardwood substrate bags if you want to skip mixing and sterilizing from scratch.

• 1 lb fully colonized grain spawn (from Step 3)
• 1 cooled 5 lb mushroom substrate bag (from Step 4)
• Still-air box or laminar flow hood
• 70% isopropyl alcohol

Spawn rate: ~15–20% colonized grain by wet weight. One 1 lb spawn bag inoculates one 5 lb substrate block.

Before opening, squeeze and knead the colonized grain bag until all clumps of grain separate completely — do not open the bag with large intact clumps still inside. Work in a still-air box with freshly sanitized surfaces and gloves. Open both the spawn bag and the substrate bag. Pour the broken-up grain spawn onto the top of the substrate and distribute it evenly across the full surface before mixing down. Mix thoroughly until no visible clumps of grain remain isolated from the mushroom substrate — the grain should be evenly distributed throughout. Seal or fold the top of the substrate bag closed.

• Inoculated substrate bag from Step 5
• Dark incubation space at 70–77°F

Place the inoculated mushroom substrate bag in a dark area at 70–77°F. Do not open the bag during colonization. Expect colonization to take 21–35 days for a 5 lb block — Neofavolus americanus colonizes at a moderate pace compared to oysters or shiitake, so patience is important. Healthy mycelium will be uniformly white to off-white with a slightly cottony texture. Any green, black, or blue-green patches indicate mold contamination; discard those blocks without opening them indoors.

• Fully colonized block from Step 6
• Fruiting chamber or grow tent with humidity and FAE (fresh air exchange) control
• Hygrometer to measure relative humidity
• Diffuse light source (12 hours on / 12 hours off)

Open or cut the substrate bag at the top to expose the block surface. Move the block into your fruiting chamber and establish conditions of 90–95% relative humidity, 66–72°F, and 4–6 fresh-air exchanges per hour. Provide diffuse low-intensity light for approximately 12 hours per day — direct bright light is unnecessary and may dry surface moisture. Mist the walls of the chamber (not the block surface directly) to maintain humidity. These are experimental parameters extrapolated from closely related polypore species; Neofavolus americanus has no published indoor pinning data, so trial and adjustment are expected.

Monitor daily. Initial pins on hardwood polypores typically appear as small white or cream-colored disks on the block surface. If no pins appear after 3 weeks, adjust humidity upward toward 95% and increase FAE frequency before adjusting temperature.

• Clean, sharp knife or scissors
• Water for block rehydration between flushes

Harvest hexagonal polypore (Neofavolus americanus) brackets when caps have expanded to their typical fan shape, the pore surface is clearly hexagonal, and the upper cap surface is still slightly supple and retains some color — do not wait until caps have fully faded to pale white or become noticeably tough. Use a clean blade to cut brackets at the base of their attachment point; avoid twisting or pulling, which can tear away chunks of colonized mushroom substrate. After harvest, remove any remaining stub material from the block surface to reduce contamination risk.

To encourage a second flush, soak the spent block in clean cool water for 4–8 hours, then drain and return to fruiting conditions. Rest the block for 7–14 days at colonization temperature (70–77°F) before reintroducing fruiting conditions. Note that flush count and yield for Neofavolus americanus indoor cultivation have not been documented; one productive flush followed by uncertain secondary growth is the realistic expectation for experimental runs.

• Fully colonized grain spawn (from Step 3, Method 1)
• Freshly cut hardwood logs — 1 log per 1 lb colonized spawn
• Drill with 5/16-inch bit, wiped with 70% isopropyl alcohol
• Melted cheese wax or beeswax and brush

Drill inoculation holes in a diamond pattern across the log face and sides, spaced approximately 3–4 inches apart and 1.5 inches deep. Wipe the drill bit with 70% isopropyl alcohol between holes and before each new log. Break colonized grain down fully inside the bag before opening — squeeze and knead until all grain separates. Pack a pinch of colonized grain firmly into each hole, pressing in so grain contacts the moist wood. Seal each hole immediately with melted wax using a small brush or dauber — no inoculation site should be left unsealed. Place inoculated logs in a shaded outdoor location with good airflow and ambient ground moisture.

• Inoculated logs from Step 3 (Continued)
• Shaded outdoor area; natural precipitation or occasional supplemental watering in dry periods

Place logs horizontally in dappled shade — under a deciduous canopy or against a north-facing structure works well. Allow natural precipitation to maintain moisture; in dry spells exceeding 2–3 weeks, water logs thoroughly by soaking or extended hosing. Do not let logs dry out completely during colonization. Colonization of a 2-to-4-inch hardwood log typically takes 6–12 months. Natural fruiting will occur in spring or fall when ambient temperatures drop into the 50–68°F range and relative humidity rises with seasonal rainfall. No intervention is required to trigger fruiting — natural temperature and humidity shifts provide the conditions Neofavolus americanus needs.