HB4 (Home Blend v4) Sterile Mushroom Substrate

$29.99

The next generation of home mushroom cultivation is here.

HB4 (Home Blend v4) is a premium, ready-to-use substrate developed by Mountain Made Mushrooms in collaboration with North Spore. Representing the fourth evolution of their acclaimed Home Blend, HB4 was fine-tuned through rigorous side-by-side comparison grows to deliver maximum yields, cleaner results, and multi-flush performance for advanced home cultivators.

Learn more about Jamo's (founder of Mountain Made Mushrooms) story on the North Spore Substack here

In Stock. Ships in 1-2 business days.

This high-performance formula features a 50/50 mix of worm castings and coco coir, enhanced with a custom nutrient pack formulated specifically for the legal cultivation of dung-loving mushroom species. It’s the same substrate that fueled the award-winning strain crowned at the Denver Psychedelic Cup 2024 — a true benchmark for consistency and potency.

Clean, nutrient-rich, and eco-conscious, HB4 offers a manure-free alternative to traditional dung-based substrates without compromising results.

Key Features
  • Precision-Tuned Formula: Fourth-generation substrate refined through multiple controlled grow trials.
  • Optimized Nutrition: Nutrient profile designed to enhance growth, fruiting, and vitality.
  • Manure-Free Alternative: Worm casting–based mix reduces contamination risk vs. traditional manure substrates.
  • Proven Performance: The choice substrate behind the 2024 Denver Psychedelic Cup–winning strain.
  • Multi-Flush Durability: Engineered to support consistent yields across multiple harvests.
  • Eco-Conscious: Made with sustainable, natural materials — worm castings and coco coir.

Why Grow with HB4

A next-gen substrate built from collaboration between two trusted mushroom brands, HB4 is scientifically refined, competition-proven, and 100% optimized for dung-loving cultivation. HB4 delivers cleaner results, stronger yields, and a premium experience for serious home growers who demand the best.

How to Use

Spawn to bulk ratio

We recommended mixing 1 colonized grain spawn bag with 2-3 bags of sterile substrate. (Higher inoculation rates may improve your success.) 

Best Practices

We recommend clean hands, latex or nitrile gloves, and sterile technique when using sterile substrate to reduce the introduction of contaminants.

Be sure to mix colonized grain spawn thoroughly into your substrate. 

It is best practice to wait a minimum of 1 week after arrival before using sterile substrates to ensure they were not compromised during transit. Rest assured that your purchase is 100% guaranteed. If your substrate was compromised, we will replace it.

Storage

Sterile substrates should be stored at room temperature out of direct sunlight. No refrigeration is necessary. They can also be stored for several months before use.

Notice

North Spore's products shall be used only for lawful purposes. North Spore does not condone Psilocybin (Psilocybe cubensis) or hallucinogenic (magic) mushroom growing in jurisdictions where it is currently illegal.

CA Prop 65 Notice

Frequently Asked Questions

We recommend absolute beginners start with our Spray & Grow Kits, which make growing mushrooms at home super easy.

We want you to have the best possible experience with every North Spore product and guarantee free replacements within 30 days of receipt for any damaged, contaminated, or unusable product.

Absolutely! Mushroom cultivation is a great activity to do with the whole family, whether you'd like to grow indoors or outdoors. If you're new to mushrooms, we recommend starting with a Spray & Grow Kit or a Plant & Grow Kit – both make it easy to grow fresh, organic mushrooms at home.

We are vertically integrated — from culture work all the way to spawn and substrate production — ensuring a quality end product. And our staff mycologists keep up to date on all best practices in our field. Additionally, we have a dedicated QAQC team that tests every batch of grain and substrate before it’s inoculated.

Cluster of brown-capped mushrooms with long, light-colored stems against a white background.

Your Trusted Source for Premium Mushroom Growing Supplies

Whether you’re growing mushrooms at home, in your garden, or at a commercial scale, we offer everything you need to cultivate success. We start with the highest-quality OMRI-listed ingredients, mix them in our state-of-the-art facility, and inoculate them in our custom-built lab, so you can rest easy knowing your product will yield the best results.

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