Hardwood Mix is a traditional mushroom substrate made from pure hardwood sawdust, designed for slow-to-moderate fruiting species that benefit from longer colonization times and prolonged fruiting phases. It comes pre-sterilized in filter patch bags and is ideal for growers seeking high-quality, low-nutrient substrates for wood-loving species.

While it uses the same base of oak sawdust as our Fast Fruiting Mix, our Hardwood Mix is supplemented with bran for a lower overall nutrient content to reduce the risk of contamination over prolonged fruiting periods.

Hardwood Mix is ideal for mushrooms with longer incubation or slower fruiting times such as Shiitake, Maitake, Reishi, and Turkey Tail.

Hardwood Mix can be used to grow most wood-loving mushrooms like Oyster and Lion's Mane, but those mushrooms typically perform better on high nutrient substrates like our Fast Fruiting Mix.

No need to sterilize if you purchased our pre-sterilized Hardwood Mix grow bags. These bags are sealed and sterilized under lab conditions and come with a 0.2 micron filter patch for gas exchange and contamination prevention.

That being said, all bags can still become contaminated if you're not using clean technique when inoculating. We strongly recommend using a still air box (SAB) or laminar flow hood during the inoculation process.

To inoculate with fully colonized grain spawn, follow these steps:

Tools and Equipment:

• Fully colonized grain spawn (e.g., rye, millet, sorghum)
  
  
• Pre-sterilized Hardwood Mix grow bag
  
  
• Still air box or flow hood
  
  
• 70% isopropyl alcohol, gloves, and face mask
  
  
• Flame-sterilized spoon or scalpel (if opening bag)
  
  
• Sealing method (tape, clamp, or impulse sealer)
  
  

Step-by-Step:

1. Sanitize your workspace and wear clean PPE.
   
   
2. Break up the grain spawn for even distribution.
   
   
3. Cut open the bag above the seal, or inject if using an injection port (liquid culture only).
   
   
4. Transfer grain spawn (0.5 to 1 lb for a 5 lb bag).
   
   
5. Seal the bag immediately and mix thoroughly.
   
   
6. Label and incubate in a clean, dark space at 68–75°F.
   
   

💡 Tip: Always work in a sanitized environment and avoid breathing directly over your materials.

Colonization takes longer than with heavily enriched substrates. Expect:

14 to 30 days for most species

Up to 45 days for shiitake and reishi, especially at cooler temperatures

These times can vary based on:

• The mushroom species
  
• Room temperature (ideal: 68–75°F)
  
• How much grain spawn you use
  
• Overall cleanliness and substrate moisture
  

Within a week or so, you’ll see white mycelium spreading across the substrate. Once the entire block turns white and firm, it’s typically ready to fruit.

Your bag is ready to fruit when all conditions are met:

• The substrate is completely white
  
• It feels firm and solid
  
• You may see pins or primordia forming through the plastic
  
• There are no signs of mold or contamination
  
  📌 Some species, like shiitake, benefit from a “resting phase” of 7–10 days after full colonization before fruiting. This can help trigger better pinning.
  

To Initiate Fruiting:

1. Cut a 2–3" X in the side of the bag or a slit just beneath the white filter patch.
   
2. Place in a high-humidity environment like:

• A monotub or plastic tote
• Fruiting tent or grow chamber
  

Maintain the Following Conditions:

• Humidity: 85–95% using humidifier
  
• Temperature: 60–75°F
  
• Light: 12/12 cycle with indirect lighting or grow lights
  
• Airflow: Passive or fan-assisted for CO₂ exchange
  
  

📌 Best Fruiting Setup for Home: Automated Martha Tent

Here's a quick overview of temperature and humidity recommendations for species that are commonly grown on this mix:

Shiitake: 55-87°F / 85-95% RH

Reishi: 70-85°F / 85-95% RH

Turkey Tail: 60-75°F / 85-95% RH

Maitake: 60-70°F / 90-95% RH

Typically you can expect 2-3 flushes per mushroom block.

• First flush is the most productive
  
• Second and third flushes are smaller
  
• Total yield varies by species and environment
  

For Second and Third Flushes:

• Let the block rest for 4–5 days
  
• Optionally soak in cold water for 4–6 hours
  
• Resume misting and fruiting conditions

Yes—but a controlled environment increases success, consistency, and quality of yields.

You can fruit on a shelf, kitchen counter, or in a room if:

• Room temps stay in the 60s–70s °F
  
• Humidity is above 80% or a humidifier is placed near your block
  
• You mist consistently and provide light and airflow
  
  
  

Not for indoor cultivation—but it’s still useful!

• Add to compost piles or garden beds
  
• Use as mulch or soil amendment
  
• Inoculate outdoor mushroom beds
  
  

Troubleshooting slow colonization:

Contamination – green, black, or pink spots; foul smell

Temps too low/high – below 65°F or above 80°F can slow or stall growth

Overhydration – water pooling in the bag

Old or weak spawn – expired or improperly stored grain spawn may not perform

If unsure, contact Redwood Mushroom Supply with photos for assistance.