How To Grow Portobello at Home

🍄 How to Prepare Malt Extract Agar (MEA) for Mushroom Cultivation

✅ What You’ll Need:

Ingredients (Standard 1 Liter Batch – Makes ~35–40 Petri dishes):

• Malt Extract: 20 grams
• Agar-Agar Powder: 15 grams
• Distilled Water: 1000 mL
• (Optional: Peptone 1–2g or yeast extract for additional nutrients)

🥣 Step 1: Mixing the Ingredients

1. Measure out 20g of malt extract and 15g of agar powder.
2. Add both to a clean 1-liter Erlenmeyer flask or heat-safe container.
3. Pour in 1 liter of distilled water.
4. Stir well until all solids are dissolved. Use a magnetic stirrer or manual stirring. The solution may be cloudy.

🔍 Tip: If you're using powdered malt extract, mix slowly to avoid clumping.

🔥 Step 2: Sterilization

1. Cover the flask with aluminum foil or a loose cap — not airtight.
2. Place it in a pressure cooker or autoclave.
3. Sterilize at 15 PSI (121°C / 250°F) for 20–30 minutes.

⚠️ Do not exceed 30 minutes to avoid caramelizing the sugars in the malt, which may inhibit fungal growth.

❄️ Step 3: Cooling

1. Allow the sterilized MEA to cool to around 50–55°C (122–131°F). It should still be liquid but not too hot to kill spores if pouring into inoculated media.
2. If using a thermometer, monitor closely. This is the ideal pouring temperature.

🧊 Do not wait too long — it will start to solidify around 40°C (104°F).

🧪 Step 4: Pouring Plates

1. Sanitize your work area thoroughly or use a laminar flow hood/still air box.
2. Pour ~20 mL of agar into each sterile Petri dish.
3. Slightly crack the lids and let them sit for 15–30 minutes until solid.
4. Once solidified, close the lids and allow the plates to fully dry for 24 hours before sealing.
5. Optional: Store plates upside down to prevent condensation from dripping onto the surface.

🧼 Label your plates with date and medium type.

📦 Storage Instructions

• Store sealed plates in ziplock bags or parafilm-wrapped stacks
• Keep refrigerated at 2–8°C (35–46°F)
• Plates are viable for up to 4–6 weeks if properly stored

🌱 Optional Additions & Notes

• Antibiotics (e.g., gentamicin) can be added after cooling (below 50°C) to prevent bacterial contamination
• Activated charcoal (0.5g/L) can be added to promote some fungal species
• Color indicators can be added for pH sensitivity, though not usually necessary for mushroom work

🍄 How to Prepare Liquid Culture (LC) Jars for Mushroom Mycelium

Liquid culture is a sterile sugar-water solution used to grow mycelium for easy inoculation of grain, agar, or other substrates. It enables fast, clean, and efficient propagation of fungal cultures.

✅ What You’ll Need

Ingredients (Standard 500 mL Batch):

• Light Malt Extract (LME): 10 grams
  (Alternative: Karo Light Corn Syrup – 4% concentration or 20mL per 500mL water)
• Distilled Water: 500 mL

🥣 Step 1: Prepare the Liquid Culture Mix

1. Add 10 grams of light malt extract (LME) to 500 mL of distilled water in your jar.
2. • If using Karo syrup, add 20 mL per 500 mL water.
2. Mix thoroughly to dissolve all sugars. Use a stir rod or magnetic stirrer for even mixing.
3. Add a magnetic stir bar to the jar if you plan to use a stir plate later (optional but recommended).

🔍 Tip: Use clear jars to visually monitor mycelium growth and contamination.

🧴 Step 2: Jar Setup & Lid Prep

1. Use a lid fitted with:
2. • Self-healing injection port (SHIP) for inoculation
   • Micropore filter or synthetic filter disc for gas exchange
2. Tighten the lid lightly to allow some venting during sterilization.
3. Cover the top of the jar with aluminum foil to prevent condensation or water from the pressure cooker entering the lid.

🔥 Step 3: Sterilization

1. Place your LC jar into a pressure cooker or autoclave.
2. Sterilize at 15 PSI (121°C / 250°F) for 20–25 minutes.
3. • Longer sterilization can caramelize sugars and darken the solution.

⚠️ Always keep jars upright and avoid overfilling the pressure cooker with water. Use a rack or trivet inside.

❄️ Step 4: Cooling

1. Let the jar cool fully to room temperature before use (may take several hours).
2. Do not inoculate while warm — it will kill your spores or culture.

💉 Step 5: Inoculation (In Sterile Conditions)

1. Use a still air box or laminar flow hood.
2. Sterilize a syringe needle with flame or alcohol.
3. Inject 1–2 mL of spore solution or agar wedge into the LC through the SHIP.
4. Optionally swirl gently or place on a magnetic stir plate for 30 mins daily.

🧬 Step 6: Incubation & Growth

• Incubate at 21–25°C (70–77°F).
• Shake or stir once daily to prevent clumping and increase oxygenation.
• Mycelium should begin showing in 3–7 days, fully colonized in 10–21 days depending on strain and environment.

🧪 Monitoring & Use

• Look for cloudy, web-like mycelium suspended in the liquid.
• Discard if you see:
• • Sediment or grainy debris
  • Smell of rot or sourness
  • Color other than white (green, black, pink = contamination)

Once colonized, the LC can be used to:

• Inoculate grain spawn
• Transfer to agar
• Create additional liquid culture jars

📦 Storage Instructions

• Store at room temperature if in use
• For long-term: refrigerate for up to 2–3 months
• Always flame sterilize the needle before every use

🍄 Shiitake Mushroom (Lentinula edodes) — Primordia Initiation & Fruiting Guide

For Fully Colonized 10 lb Supplemented Hardwood Blocks

🧬 1. Observe Colonization Progress

Shiitake colonizes substrate below the surface first, which can be misleading.

✅ Key colonization phases:

• Weeks 1–3: White mycelium spreads internally, little surface change
• Weeks 3–4: Entire surface is visibly white and cottony
• Weeks 4–6+: Mycelium begins to brown (metabolite pigmentation) as it matures

🔍 Browning = maturity, not contamination. This is a natural hardening of the block’s surface and is essential before fruiting.

⏳ 2. Timing: Wait for Full Browning (Crucial for Shiitake)

Before initiating primordia, your 10 lb shiitake block should:

• Be 100% colonized (no visible substrate)
• Show deep golden-to-cinnamon brown coloration
• Appear dense and firm to the touch

🕒 This can take 6–8 weeks post-inoculation, depending on the strain and environment.

🧊 3. Cold Shock to Trigger Primordia

Unlike many other species, shiitake requires a temperature drop (“cold shock”) to initiate pin formation.

❄️ Cold shock process:

1. Remove the plastic bag entirely once the block is fully colonized and browned.
2. Submerge the exposed block in cold water (35–45°F / 1–7°C) for 4–12 hours.
3. • Use a clean tub or sink
   • Ensure full submersion (weigh it down if needed)
3. Remove and drain for 15–30 minutes.

⚠️ Do not soak early or for too long — this may damage the block or lead to contamination.

🌱 4. Move to Fruiting Environment

After the soak, transfer the block to a high-humidity fruiting space, such as:

• A grow tent
• A shotgun fruiting chamber
• A humidity-controlled room

Ideal fruiting conditions for shiitake:

• Temperature: 55–70°F (13–21°C)
• Humidity: 85–95% RH
• Lighting: 12 hours/day, 6500K spectrum
• Fresh Air Exchange: High — at least 4–6 air exchanges/day

👁️ 5. Watch for Primordia Formation

Primordia (baby mushrooms) begin forming in 3–7 days post-soak.

Signs you're on track:

• Tiny dark-colored bumps appear on the block
• They quickly grow into small, brown dome-shaped caps
• Block remains firm, not soggy or discolored

🍄 Shiitake Fruiting Guide (Lentinula edodes)

For 10 lb Supplemented Hardwood Substrate Blocks

Phases, Environmental Control & Harvesting

Shiitake mushrooms fruit in distinct biological phases that require specific changes to temperature, humidity, light, and fresh air exchange (FAE). Managing these phases properly ensures strong flushes, dense fruit bodies, and multiple successful harvests.

🌱 PHASE 1: Browning & Consolidation (Pre-Fruiting)

Duration: ~4–6 weeks after full colonization
Environment: 70–75°F (21–24°C), dark or low light

What's happening:

• Mycelium finishes internal colonization
• Surface transforms from white to golden-brown (“skin” forms)
• Block densifies and builds fruiting potential

✅ Key Signs to Wait For Before Fruiting:

• Surface fully browned and hardened
• No white mycelial regrowth or exposed substrate
• Block has a firm, leathery feel
• Colonization period complete (minimum 40–45 days)

⏳ Patience is key — premature fruiting = weak or aborted mushrooms.

❄️ PHASE 2: Cold Shock & Soaking (Initiation Trigger)

Timing: After browning is fully complete
Trigger Method: Cold water soak

Procedure:

1. Remove block from the bag (or cut large slits if bag-fruiting)
2. Submerge in cold clean water (36–45°F / 2–7°C) for 4–12 hours
3. Weigh down if necessary to ensure full contact
4. Drain thoroughly and allow excess moisture to drip off for 15–30 min

Purpose:

• Simulates rainfall and seasonal drop in temperature
• Triggers primordial (pin) formation

💧 Do not soak early — it may lead to rot or contaminate the block.

🍄 PHASE 3: Pinning & Fruiting

Duration: ~5–10 days
Environment:

• Temp: 55–70°F (ideal: 60–65°F / 16–18°C)
• Humidity: 85–95% RH
• Light: 12 hours/day of indirect light, 6500K (avoid total darkness or direct sun)
• FAE: High — shiitake needs clean, moving air to fruit properly

What to watch for:

• Dark brown bumps appearing across the block (primordia)
• Rapid development into button-sized caps
• Mushrooms double in size every 24–48 hours during peak growth

✅ Keep the block moist, but not soaked. Mist walls or air above the block as needed.

✂️ PHASE 4: Harvesting

Ideal Harvest Time:

• Cap is expanded and slightly convex, not fully flat
• Veil under the cap is torn, but spore drop hasn’t started
• Mushroom feels firm and heavy
• Color is rich brown (strain-dependent)

Harvesting technique:

• Twist and pull gently from the base
• OR cut cleanly with a sanitized knife or scissors
• Avoid damaging nearby pins — harvest in clusters where possible

⛔ Overmature shiitake become spongy, release spores, and are prone to rot.

🔁 PHASE 5: Rest & Re-soak for Future Flushes

After harvest:

1. Remove stem stubs and surface debris
2. Let the block rest in fresh air for 7–10 days (no soak)
3. Re-soak in cold water for another 4–12 hours
4. Resume fruiting conditions

📦 A healthy shiitake block can produce 2–4 flushes, with second and third flushes often larger and more attractive than the first.

🧪 Common Issues & Fixes