Video from Mike Crowe of Southwest Mushrooms

Master’s Mix: The Ultimate Substrate for Fast-Fruiting Mushroom Varieties

Creating the perfect growing medium is one of the most critical aspects of successful mushroom cultivation. For commercial growers and serious hobbyists alike, the “Master’s Mix” has become the gold standard substrate for fast-fruiting mushroom varieties, offering exceptional yields and versatility. This comprehensive guide will walk you through everything you need to know about creating your own Master’s Mix, from ingredients and equipment to the mixing process and sterilization techniques.

What is Master’s Mix?

Master’s Mix is a premium substrate formulation consisting primarily of hardwood sawdust pellets and supplemental nutrients. It’s designed specifically for fast-fruiting mushroom species and delivers impressive yields with biological efficiency rates often reaching 100% or higher. This means that for every pound of dry substrate used, you can potentially harvest a pound or more of fresh mushrooms.

If you do not want to go through this process to make your own Master’s Mix just purchase our custom made Fast-Fruiting mix we do all of the work for you.

Mushroom Varieties That Thrive on Master’s Mix

Master’s Mix is incredibly versatile and supports a wide range of gourmet and medicinal mushroom species:

• Lion’s Mane
• Oyster mushrooms (all varieties)
• Chestnut mushrooms
• Pioppino (Agrocybe aegerita)
• Reishi
• Maitake
• Beech mushrooms

  It is most known for Oyster Mushroom production. As with all mushroom farm efforts you should test the substrait that works best for your strain, or variety and your local conditions.

Ingredients for Master’s Mix

The Base Recipe

The standard Master’s Mix formula uses a 50/50 ratio of:

• Hardwood pellets (preferably oak)
• Soybean hull pellets
• Water (approximately 50-60% moisture content)
• Optional: Gypsum (small amount)

For a commercial-scale batch of approximately 900 pounds of substrate:

• 200 pounds of oak hardwood pellets
• 200 pounds of soybean hull pellets
• 240-260 liters of water
• A few cups of gypsum (calcium additive)

For small-scale production, you can scale this down to:

• 20 pounds of oak hardwood pellets
• 20 pounds of soybean hull pellets
• 24-30 liters of water
• A small amount of gypsum

Sourcing Your Ingredients

Hardwood Pellets

Hardwood pellets are compressed sawdust that expand when water is added. These can be found at:

• Local hardware stores
• Home improvement centers like Home Depot or Ace Hardware
• Specialty stores that sell pellet stoves and grills
• Online suppliers like Mushroom Media Online

Look for 100% hardwood pellets without additives or binders. While oak is preferred, other hardwoods work well too:

• Maple
• Cherry
• Hickory
• Alder
• Or blends of different hardwoods

For commercial operations, consider ordering in bulk by the ton from local suppliers or directly from pellet manufacturers.

Soybean Hull Pellets

Soybean hulls are the outer coverings of soybeans and provide excellent nutrition for mushroom mycelium. These can be sourced from:

• Agricultural feed stores
• Farm supply outlets
• Specialty mushroom cultivation suppliers

The soybean hulls used in mushroom cultivation are actually an agricultural byproduct, making this an environmentally friendly choice that recycles what would otherwise be crop waste.

Alternative Supplements

While soybean hulls are the preferred supplement for Master’s Mix, other options include:

• Wheat bran
• Rice bran
• Beet pulp pellets

For shiitake-specific substrate, many growers use a mix of:

• 40 pounds oak hardwood pellets
• 10 pounds wheat bran

Equipment Needed

For Commercial Production

• Substrate mixer (a repurposed cement mixer can work for smaller operations)
• Water meter or measuring device
• Substrate bins for holding mixed material
• Filter patch grow bags (typically 5T with 0.5-micron filter patch)
• Heat-resistant gloves
• Sterilization equipment (autoclave or pressure sterilizer)
• Clean work surface for bagging

For Small-Scale/Home Production

• Large mixing containers (plastic totes work well)
• 5-gallon buckets for measuring water
• Filter patch grow bags (smaller 3T-sized bags for 5-7 pound blocks)
• Kitchen scale for measuring ingredients
• Pressure cooker (minimum 15 PSI for proper sterilization)
• Heat-resistant gloves

The Mixing Process

Step 1: Prepare Your Equipment

• Set up your mixing area with all supplies readily accessible
• Connect your water source and measuring device
• Open ingredient bags for easy access
• Prepare empty bins for holding mixed substrate

Step 2: Initial Hydration of Hardwood Pellets

1. Add your hardwood pellets to the mixer
2. Begin adding water gradually while mixing
3. For a 400-pound batch (200 pounds of each ingredient), add approximately 130 liters of water at this stage
4. Allow pellets to break down completely into sawdust

Note: Hardwood pellets are hydrated first because they take longer to break down than soybean hull pellets.

Step 3: Add Supplements

1. Stop the mixer after hardwood pellets have fully hydrated
2. Add your soybean hull pellets on top
3. Resume mixing while adding additional water
4. For our 400-pound example, add approximately 120 more liters of water (bringing total to 240-260 liters)
5. If using gypsum, add a few cups at this stage

Step 4: Testing for Field Capacity

Field capacity is the ideal moisture level where:

• When squeezed firmly, only a drop or two of water should come out
• The substrate should hold its shape when squeezed
• The substrate should be thoroughly hydrated but not soggy

To test:

1. Take a handful of substrate
2. Squeeze as hard as you can
3. Very little to no water should come out
4. The substrate should maintain its compressed shape

If too dry, add more water. If too wet, add more dry ingredients.

Small-Scale Alternative Method

If you don’t have a mixer:

1. Place hardwood pellets in a large container
2. Heat water to 170-180°F (77-82°C)
3. Pour hot water over pellets
4. Cover and allow to hydrate for about an hour
5. Add supplements and mix thoroughly by hand
6. Test for field capacity
7. Cool to room temperature before adding spawn

Bagging Your Substrate

Commercial Method

1. Place collection bin under mixer output
2. Release substrate into bin
3. Fill bags approximately halfway (for 10-pound blocks, about 3 scoops per bag)
4. Fold bags neatly following the natural creases
5. Remove excess air
6. Fold the top flap underneath the block to create a compact package
7. Prepare for sterilization

Home Method

1. Scoop substrate into filter patch bags
2. Fill only to about 50-60% capacity to allow for proper folding
3. Fold following the same principles as above
4. Prepare for pressure cooking

Sterilization Process

Proper sterilization is critical when using supplemented substrates like Master’s Mix.

Commercial Sterilization

• Load prepared bags into an autoclave or commercial sterilizer
• Run at 15 PSI for 2.5-3 hours
• Allow to cool naturally to at least 80°F (27°C) before inoculation
• Total process typically takes about a day including cooling time

Home Sterilization

• Load prepared bags into a pressure cooker
• Ensure bags are not tightly packed and water level is appropriate
• Run at 15 PSI for 2.5 hours
• Allow to cool completely before handling
• Inoculate when temperature drops to 80-85°F (27-29°C)

Inoculation and Incubation

After sterilization and cooling:

1. In a clean environment (preferably in front of a laminar flow hood), open the bags
2. Add grain spawn at a rate of 10-20% of substrate weight
3. Mix thoroughly or layer spawn within the substrate
4. Seal bags
5. Incubate at appropriate temperature for your mushroom variety (typically 70-75°F or 21-24°C)
6. Allow 2-3 weeks for complete colonization

Yield Expectations

With properly prepared Master’s Mix, you can expect:

• Biological efficiency of around 100% (1 pound of fresh mushrooms per 1 pound of dry substrate)
• 2-3 pounds of mushrooms from a 10-pound block on first flush
• 2-3 flushes per block
• Total yield of 3-5 pounds per 10-pound block

Advantages of Master’s Mix

1. Higher Yields: The supplementation with soybean hulls can triple yields compared to unsupplemented substrates
2. Versatility: Works for a wide variety of gourmet and medicinal mushrooms
3. Storage Efficiency: Pelletized ingredients store compactly until needed
4. Consistency: Provides reliable results with proper technique
5. Sustainability: Uses byproducts from other industries (sawdust and agricultural waste)

Troubleshooting

Common Issues and Solutions

1. Contamination: Usually indicates insufficient sterilization or poor aseptic technique. Ensure proper pressure and time during sterilization, and use clean techniques during inoculation.
2. Poor hydration: If substrate is too wet or too dry, colonization and fruiting will suffer. Master the field capacity test to ensure optimal moisture.
3. Slow colonization: Could indicate temperature issues, low spawn rate, or poor substrate quality. Maintain proper incubation temperatures and use fresh materials.
4. Low yields: May result from improper nutrition, poor environmental conditions during fruiting, or genetic factors. Ensure proper substrate formulation and maintain optimal fruiting conditions.

Conclusion

Master’s Mix has become the industry standard for fast-fruiting specialty mushrooms for good reason. With its optimal balance of structure, nutrition, and moisture retention, it provides an ideal environment for mycelial growth and mushroom formation. Whether you’re a commercial grower looking to maximize production efficiency or a home cultivator seeking the best possible yields, mastering the Master’s Mix will elevate your mushroom cultivation to the next level.

By following the guidelines in this article, you’ll be well on your way to producing professional-quality substrate for your mushroom farm or home growing operation. Remember that consistency in process and attention to detail are key to successful mushroom cultivation with Master’s Mix.