How to Grow Shiitake CW 40-60F (Lentinula edodes)

• 1 lb dry rye, wheat, or barley grain (single batch)
• Water for soaking and simmering
• Medium mushroom grow bag with 0.2-micron filter patch
• Pressure cooker capable of holding 15 PSI

Scale-up: 3 lbs grain → 3 spawn bags | 5 lbs grain → 5 spawn bags

Rinse the grain and soak it fully submerged in cool water for 12–18 hours at room temperature, then drain thoroughly. Transfer the soaked grain to a pot, cover with fresh water, and simmer for 15–20 minutes until kernels are fully hydrated but still intact — they should feel firm, not mushy. Drain completely in a colander and spread on a clean surface to surface-dry until kernels feel dry to the touch with no visible moisture on the outside, which takes 20–30 minutes. Load the dried grain into the grow bag, leaving several inches of headspace, and seal the bag by folding the top and securing it with a zip tie or impulse sealer. Place the loaded bags in your pressure cooker and sterilize at 15 PSI for 90–120 minutes, allowing the cooker to cool to room temperature entirely before opening. Once cooled, move bags to your still-air box or flow hood and inoculate with 3–5 cc of Shiitake CW 40-60F liquid culture per 1 lb bag, injecting through the filter patch or self-healing port. Out-Grow carries Shiitake CW 40-60F Lentinula edodes liquid culture ready to inject: Shiitake CW 40-60F Liquid Culture. Out-Grow also carries sterilized grain bags ready to inoculate if you want to skip this step: Sterilized Grain Spawn Bags.

• 4 lbs hardwood sawdust pellets (oak or mixed hardwood)
• ¾ lb wheat bran
• ¼ lb gypsum
• Approximately 5½ cups water (added gradually to reach field capacity)
• Large mushroom grow bag with 0.2-micron filter patch
• Pressure cooker capable of holding 15 PSI

Scale-up: For 3 blocks multiply each ingredient by 3. For 5 blocks multiply by 5.

Pour the hardwood sawdust pellets into a large mixing container and add the wheat bran and gypsum. Add water gradually while mixing until pellets fully break down into fine sawdust. Continue adding water and mixing until the mushroom substrate passes the squeeze test: when you squeeze a fistful firmly, only a few drops of water appear — not a steady stream. If water streams freely, the mushroom substrate is too wet; allow it to air out and mix again. Do not supplement with more than 20–25% bran by dry weight — higher supplement ratios above 45% substantially increase contamination risk for Lentinula edodes. Load the mixed mushroom substrate into the large grow bag, pressing to eliminate air pockets, and seal. Sterilize at 15 PSI for 90–120 minutes, then allow to cool completely to room temperature before inoculating. Out-Grow carries ready-to-use hardwood mushroom substrate bags if you want to skip this step: Wood-Based Inoculate and Wait Mushroom Substrates.

• 1 fully colonized grain bag (from Step 1)
• 1 cooled sterilized sawdust block (from Step 2)
• 70% isopropyl alcohol for surface wipe-down
• Still-air box or laminar flow hood

Work inside your still-air box or in front of a laminar flow hood. Wipe all exterior surfaces of both bags with 70% isopropyl alcohol. Before opening the grain bag, break the colonized grain down fully by squeezing and kneading the bag firmly until every grain separates and no clumps remain — the contents should move freely inside the bag. Open both bags in the clean work area, pour the broken grain spawn across the surface of the mushroom substrate evenly with no concentrated pockets, then fold down the tops and fold-and-knead the spawn throughout the mushroom substrate until grain is fully distributed with no isolated clusters visible. Seal the inoculated block bag and label it with the date. Never inoculate warm mushroom substrate — heat kills liquid culture and freshly grown grain spawn alike. Use a spawn rate of approximately 10% grain spawn by weight relative to the sawdust block.

• Inoculated sawdust block in sealed bag
• Warm, dark or low-light space holding 70–80°F
• Thermometer to monitor ambient temperature

Place the sealed blocks in a warm space that holds 70–80°F. Shiitake CW 40-60F (Lentinula edodes) colonizes slowly — full colonization and the browning stage combined take 60–90 days. Do not disturb bags during this period. In the first few weeks, mycelium appears bright white and cottony as it spreads through the mushroom substrate. Over the following weeks, Lentinula edodes forms a dense, thick outer skin that gradually turns tan and then a uniform brown — this is called dermalization, and it is a required maturation stage, not a sign of contamination. Do not move blocks to fruiting conditions until the entire surface has browned evenly and the block feels firm and solid throughout. Blocks introduced to cool fruiting conditions before full browning will produce weak or absent flushes. Maintain ambient humidity sufficient to prevent bag drying; no precise RH target is required during the spawn run itself while bags remain sealed.

• Fully colonized and browned Lentinula edodes block
• Refrigerator or space holding 35–40°F for 24–48 hours
• Fruiting environment: 40–60°F ambient, 80–95% RH, fresh air exchange (FAE) keeping CO₂ below 1,200 ppm
• Diffuse light source, 8–12 hours per day

Place the fully browned block in a refrigerator or cold space at 35–40°F for 24–48 hours without opening the bag — this cold shock triggers primordia initiation in the CW 40-60F strain of Lentinula edodes. After cold shock, move the block to your fruiting environment and open or cut the bag to expose the block surface. The fruiting environment should hold 40–60°F with the CW 40-60F strain; pinning typically prefers the upper half of that band around 50–60°F. Maintain 80–95% RH using a humidity tent, grow tent, or automated humidifier, and ensure fresh air exchange several times daily to keep CO₂ below 1,200 ppm. Provide diffuse light sufficient to read comfortably in the room for 8–12 hours per day. First pins appear as small brownish nodules emerging through cracks in the browned skin surface, typically 3–7 days after the cold shock.

• Pinning Lentinula edodes block
• Humidity: 80–95% RH, no direct airflow on pins
• Temperature: 40–60°F (CW 40-60F strain)
• Fresh air exchange: CO₂ below 1,200 ppm throughout development
• Diffuse light: 8–12 hours per day

Maintain 80–95% RH throughout pin development, particularly in the first 3–4 days after pins appear — humidity drops below 70% during this window cause pin abortion. Ensure fresh air exchange happens regularly while directing airflow away from the block surface; direct airflow dries pins and causes caps to crack or abort. Shiitake CW 40-60F mushrooms develop from pin to harvest-ready in approximately 6–10 days under stable conditions. Caps should remain slightly convex and slightly rolled under at the margins; gills should be fully formed but not yet fully exposed. As caps approach 70–90% expansion, monitor daily. If CO₂ rises above 1,200 ppm, stems elongate and caps remain small and thin-fleshed — increase fresh air exchange immediately. Light is necessary for proper cap development; blocks kept in the dark produce elongated stems and undersized caps.

• Clean, sharp knife
• Harvest container or tray

Harvest each shiitake mushroom when the cap is 70–90% expanded — margins still slightly curled under, gills fully formed but not fully flattened, and white veil remnants may still be present on the stem. Cut each mushroom at the base of the stem cleanly with a sharp knife rather than pulling or twisting. Pulling tears chunks of the browned block surface and creates open wounds that invite contamination in subsequent flushes. Over-mature Lentinula edodes have fully flattened or upturned caps, darkening gills with visible spore dust, and tougher fibrous stems — quality and shelf life decrease markedly, and the extra substrate drain reduces second flush performance. Harvest the entire flush within a short window rather than letting mushrooms mature at different rates, which forces some to over-mature while others are still developing. Remove all mushroom stumps and any aborted pins from the block surface after each flush to prevent rotting material from becoming a contamination point.

• Harvested Lentinula edodes block
• Large bucket or cooler of cold water (40–50°F)
• Weight to submerge block fully
• Rest period: 7–14 days at room temperature before re-shocking

After harvest, allow the block to rest at room temperature for 7–14 days to recover carbohydrate reserves. Then submerge the block fully in 40–50°F water for 4–12 hours to rehydrate and re-trigger fruiting — weigh it down if needed to keep it submerged. After the cold water dunk, return the block to fruiting conditions at 40–60°F with 80–95% RH and repeat Steps 5 and 6. Shiitake CW 40-60F (Lentinula edodes) blocks typically produce 2–3 productive flushes, with the first flush the heaviest and subsequent flushes progressively lighter. A spent block is identifiably lighter than a fresh block, feels dry even after a full dunk, fails to produce pins after standard rest and re-soak, and may show spreading contamination. Discard blocks that do not respond with at least modest pinning after a normal rest and cold water dunk cycle.

Follow Method 1, Step 1 exactly to produce colonized grain spawn from Shiitake CW 40-60F Lentinula edodes liquid culture. One fully colonized 1 lb grain bag is sufficient to inoculate 1–2 standard logs.

• Freshly cut oak, sugar maple, or beech log (3–8 inches diameter, 3–4 ft long)
• 1 colonized grain bag per 1–2 logs
• Drill with 5/16-inch bit
• Melted cheese wax or beeswax and dauber

Use freshly cut hardwood logs that have rested 1–4 weeks after cutting — logs cut too recently may still contain antifungal compounds, while logs older than 6 weeks may harbor competing fungi. Drill holes approximately 1 inch deep in a diamond pattern across the log: rows spaced 6 inches apart, holes offset within each row, giving approximately 30–50 holes per standard 3–4 ft log. Break the colonized grain bag down fully by kneading until grain separates completely, then open the bag and pack grain spawn into each drilled hole, pressing firmly to eliminate air gaps. Immediately seal each filled hole with a small amount of melted wax applied with a dauber to prevent drying and contamination entry. Work quickly to minimize exposure time between filling and sealing.

• Inoculated logs
• Shaded outdoor location (80% shade minimum) protected from drying wind
• Ambient temperature: 45–75°F during the spawn run, with optimum around 60–70°F

Stack or lean inoculated logs in a shaded outdoor location where they will not dry out rapidly — under a shade cloth, in woodland, or against a north-facing structure. The CW 40-60F strain of Lentinula edodes colonizes logs most actively when ambient temperatures sit in the 60–70°F range. Keep logs off bare ground to prevent rapid moisture loss or contamination wicking from soil. Water logs during dry periods to prevent the bark from drying out, which stalls colonization. Full log colonization takes 6–18 months depending on log diameter, wood density, and ambient temperatures — small-diameter logs in warm seasons colonize faster than large, dense logs in cool regions. Do not attempt to force fruiting until logs have fully colonized, which is indicated by visible white mycelium when you peel back a section of bark.

• Fully colonized Lentinula edodes logs
• Large bucket or stock tank
• Cold water: 40–60°F
• Weight to submerge logs

Submerge logs fully in 40–60°F water for 12–24 hours, weighting them down to keep them submerged. For the CW 40-60F strain of Lentinula edodes, soak water temperature in the 40–60°F range is appropriate — this cold-season strain does not require pre-warming before the soak. After soaking, stand logs upright or stack them in a shaded outdoor location where ambient temperatures sit in the 40–60°F band. Pins typically appear within 7–14 days of soaking under appropriate cool ambient conditions. Shiitake CW 40-60F produces 2–4 flushes per year from forced logs, with natural flushes also occurring during cool spring and fall weather. Rest logs 6–8 weeks between forced soakings to allow recovery.