Grain Spawn Bag (3lb) - Mushroom Grain Bag - Sterile

Sterilized Grain Spawn Bags for Mushroom Cultivation – 3lb Milo with Injection Port

Looking for a solid start to your next grow? Our 3lb grain spawn bag is packed with nutrient-rich milo grain (sorghum) and sterilized under high pressure for hours. Each bag is sealed up fresh with a self-healing injection port, so inoculation is quick, clean, and stress-free.

Our sterile grain bags are built for reliability—less chance of contamination, more time watching your mycelium thrive. Perfect for first-timers who want an easy start or seasoned growers looking for consistent results.

Whether you’re expanding into bulk substrate or keeping it simple, these grain spawn bags for mushrooms give you the flexibility to scale your cultivation without the stress.

Why Choose Our Mushroom Spawn Bags?

• 3lb of Milo Grain → Premium grain that colonizes evenly, resists clumping, and supports strong mycelium growth.

• Injection Port Convenience → Self-healing port for clean, easy inoculation with spores or liquid culture—no tape or extra steps needed.

• Sterilized & Sealed → Pressure sterilized at 17 PSI, sealed behind a HEPA flow hood to ensure sterile mushroom grow bags every time.

• Unicorn Brand Bags → Thick, professional-grade grain spawn bags with .2 micron filter patches for ideal gas exchange.

• Beginner & Expert Friendly → Works for first-time growers or as inoculation bags for advanced mushroom cultivation projects.

Ingredients – What's in the Bag?

Grain Type: Milo (Sorghum) – We use 3 lbs of high-quality Milo grain in every bag. Why Milo? Because it’s a favorite in mushroom cultivation for a reason:

• Ideal Size & Texture → Milo grains are small and uniform, giving mycelium more surface area to colonize quickly. Faster colonization = less chance for contamination.
• Moisture Retention → Milo holds just the right amount of water without turning soggy, keeping conditions balanced for healthy mycelium growth.
• Nutrient-Rich → Packed with starches and nutrients, Milo provides steady fuel for strong, resilient mycelium.
• Versatility → Works beautifully with spores, liquid culture, or grain-to-grain transfers—making it one of the most reliable grains for spawn.

No filler, no shortcuts—just sterilized Milo grain prepared with care, because the foundation of a good harvest starts with the right spawn.

Our Sterile Process (How We Prepare Each Bag)

We don’t cut corners. Each sterile grain bag follows a careful process:

1. 24-Hour Soak with Gypsum – Improves hydration and prevents clumping.

2. 15-Minute Simmer – Prepares the grain for rapid colonization.

3. 60-Minute Drying – Ensures proper moisture balance.

4. Bagging in Unicorn® Bags – .2 micron filter patch allows gas exchange without contamination.

5. 90-Minute Sterilization at 17 PSI – Complete sterilization for reliable results.

6. Sealed in HEPA Environment – Final step ensures a clean, contamination-free spawn bag.

Frequently Asked Questions

How much spore syringe do I use for a 3lb grain spawn bag?

We recommend 3-5 cc of spore solution or liquid culture for best results. Too little slows colonization, while too much risks excess moisture.

What makes Milo better for grain spawn?

Milo is a nutritious, small-sized grain that spreads mycelium quickly and resists clumping, making it ideal for mushroom inoculation bags.

Can I grow mushrooms directly in this spawn bag?

Yes, you can fruit mushrooms directly in the bag, but these mushroom grain spawn bags are designed for expanding into bulk substrate. Fruiting inside the bag works, but mixing your colonized grain into a bulk substrate usually produces larger harvests.

Are these sterile mushroom grow bags reusable?

No. Once used, sterilized grain bags should not be reused. For consistent results, always start with a fresh sterile grain bag.

Do these spawn bags work with liquid culture as well as spores?

Yes. Our injection port bags are compatible with both spore syringes and liquid cultures.

Ready to Grow?

If you need reliable mushroom spawn bags with injection ports, our sterilized grain bags are the perfect foundation for your next grow. Strong, sterile, and easy to inoculate—everything you need to kickstart healthy mushroom cultivation.

👉 Shop our full line of all-in-one grow bags, bulk substrates, agar plates, and liquid cultures to support every stage of your mushroom growing journey.

• Arrival Times: See item in cart checkout for accurate arrival times.
• Processing Times: Most orders can be processed within 0-2 days. Small orders will be processed same day if ordered before 1pm.
• International Orders: Buyers are responsible for any customs and import taxes that may apply. Seller is not responsible for delays due to customs.

• Returns accepted on equipment & supplies.
• Product must be unopened in original manufacturers packaging.
• Returns accepted for 7 days.
• Customer provides return shipping.
• No restocking fees to buyer.
• Final sale items: Perishable products (grain, substrate, all in ones, agar, liquid culture, cultures) are not returnable.

IF YOUR ITEMS ARRIVES DAMAGED: Reach out to our support team so we can make it right for you. 💪💪