Collection: Sterile Grain
& Substrates

Sterilised grain is used to start mushroom spawn: the grain is colonised with a suitable gourmet mushroom culture. Substrate is the growing medium that the colonised grain is mixed into to give the mycelium room to spread before fruiting.

Grain provides a starting point for mycelium to grow and spread. Substrate provides the larger growing medium used after the grain has fully colonised. They do different jobs, so many growers use them together.

Both are sterilised grain options for starting spawn. Millet is a blend of millet and milo; rye is made with organic rye grain. Choose the grain that suits your preference and growing setup. Both are designed to pair with substrate for gourmet mushroom cultivation.

CVG stands for coco coir, vermiculite and gypsum. Our sterilised CVG substrate is a pre-prepared blend intended to be mixed with fully colonised grain spawn. It is not designed to be inoculated on its own.

You can buy grain spawn and CVG substrate separately, or choose the Millet Grain Spawn + CVG Bulk Substrate Bundle, which includes both. Check the product listing for the contents and size of the option you select.

The bags are prepared and sterilised, but the grain spawn is not inoculated. It needs a suitable gourmet mushroom culture, which is sold separately. CVG substrate is used with fully colonised grain rather than inoculated directly.

Growing times vary depending on the mushroom species, culture and conditions. Colonisation can take several weeks, so allow time for each stage and follow the product guide for the setup you’re using.

Use them soon after delivery where possible. If you need to store them, keep the sealed bags in the fridge and follow the storage guidance on the relevant product page.

They’re a more hands-on option than an all-in-one grow kit, as you’ll need to work through the stages of starting spawn and preparing it for fruiting. If you’re new to growing, read the product guide before you begin; an all-in-one kit may be a simpler first step.

The grain and CVG products are intended for gourmet varieties such as Oyster, Lion’s Mane and Shiitake. Choose a suitable culture for the species you want to grow, and always follow the laws and regulations where you live.