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Sterilized grain spawn Pasteurized CV Prime substrate Made for US growers
MushRealm Collective · USA bench

Grain & substrate
built for the realm.

Sterilized milo grain spawn and pasteurized CV Prime substrate for gourmet growers in the USA. Small batches, filter-patch bags, ships from California.

  • Sterilized
  • Injection-port grain bags
  • Filter-patch sub bags
  • Ships from California
Sterilized milo grain spawn bagCV Prime coir and vermiculite substrate bag
MushRealm Collective crest Grain spawnfrom $15 CV Primefrom $34.99
The staples

Every grow starts with two bags.

Step 01 is live mycelium of the gourmet species you want to grow, and that part is yours. We make the two bags it runs through: sterilized grain to colonize first, and pasteurized CV Prime to fruit from.

3 lb and 5 lb grain spawn · 5 lb and 10 lb CV Prime · matched kits
Step 01 · choose your grainSTERILIZEDSterilized milo grain spawn bag, 3 lb

Grain spawn

$153 lb bag

Fully hydrated milo grain, pressure-sterilized and sealed in a 0.2 µm filter-patch bag with a self-healing injection port. Inoculate the moment it lands.

Weight
Grain
1
Step 02 · choose your substratePASTEURIZEDCV Prime coir and vermiculite substrate bag, 5 lb

CV Prime substrate

$34.995 lb bag

The original MushRealm ACS recipe, the exact blend ACS runs in every grow: coir and vermiculite, pasteurized and hydrated to field capacity. Mix in colonized spawn and fruit straight from the bag.

Weight
1
Step 03 · or grab the pairMATCHED PAIRGrow kit bundle, USA grow kit

Grow kit bundle

$44.99Single kit

One 3 lb grain spawn bag and one 5 lb CV Prime bag, matched for a single grow. No autoclave, no guesswork.

Size
1
$5.62 per lbFull details
Two realms, one bench

Packed where you grow.

The site shows one realm at a time so prices, weights and shipping are always right for you. Switch any time.

You are here

United States

  • 3 lb and 5 lb sterilized milo grain spawn
  • 5 lb and 10 lb pasteurized CV Prime
  • Grow kit bundles
  • Prices in USD · ships from California · UPS Ground
Shop the US menu

United Kingdom

  • 1 kg sterilized oat grain spawn
  • 2.2 kg pasteurized CV Prime
  • Starter kit, the 1 : 2 pairing
  • Prices in GBP · ships from the UK · Royal Mail tracked
Shop the UK menu
How it works

From bag to harvest in four moves.

No autoclave, no pressure cooker. Everything arrives sterilized or pasteurized and sealed.

01 · Inoculate

Add live mycelium of your chosen gourmet species to the grain through the self-healing port.

02 · Colonize

Let the mycelium run through the grain, then mix it into CV Prime at about 1 : 2.

03 · Fruit

Fresh air and humidity. Pins form and the mushrooms take off.

04 · Harvest

Pick at peak, rest the block for a second harvest, and log it in your Grow Dashboard.

Build your grow

How much do you actually need?

Tell the planner how many tubs you are filling and how heavy you like to spawn. It works out the grain, the substrate and the cheapest way to buy it from the USA menu.

Open the planner
From the blog

Grow it right the first time.

Plain-English guides from the MushRealm bench, from your first grain bag to your second flush. All guides

Straight answers

Questions, answered.

Products, shipping, payment and the arrival guarantee. Still stuck? A real person answers every message.

Contact us
What is the difference between grain spawn and substrate?
Grain spawn is sterilized grain that you inoculate with live mycelium of the mushroom you are growing. It is the starter the mycelium colonizes first. Substrate (our CV Prime blend) is the bulk material you mix colonized spawn into so the mushrooms can fruit. The kit includes both.
What can I grow with it?
Our grain spawn suits practically every gourmet species: oyster, lion's mane, shiitake, reishi and more. CV Prime is coir-based, so it is the right bulk for oyster varieties and works as a casing layer. Wood lovers such as shiitake and lion's mane fruit best on hardwood sawdust.
Do you ship to me?
The US menu ships to all 50 states and DC from California, usually UPS Ground. Growing in the UK? Our UK shop ships within the United Kingdom. See our shipping policy.
What if a bag arrives contaminated or damaged?
We replace it or refund it. Send a photo within 7 days of delivery with your order number. See returns and refunds.
How do I pay?
By card (Visa, Mastercard or American Express) on a secure checkout. Payments are processed by Stripe and we never see or store your card number. Prices are in US dollars.
Arrival guaranteeReplaced or refunded. Photo within 7 days.
Ships in 1 to 2 business daysShips from California. Tracked.
Secure checkout by StripeWe never see your card number.
Real people answerReplies within 1 business day.