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Spore & Culture

Grain Spawn Bag

Pre-hydrated grain in a filter-patch bag, ready for inoculation.

Illustration of a grain spawn bag
Typical specifications
Typical fill weight1 – 3 kg hydrated grain
Grain typesRye, millet, wheat, sorghum
Filter patch0.2 – 0.5 µm, 2–4 patches
Moisture target45 – 55%
Sterilisation15 PSI / 121 °C for 90 min
Colonisation time10 – 21 days
Spore & CultureSmall to large batches

Overview

A grain spawn bag pairs hydrated cereal grain with a breathable filter patch and an injection port. The grain provides a dense nutritional base that mycelium spreads through quickly, and the finished bag becomes the inoculum for larger substrate blocks. It is the workhorse of a mid-size grow.

Primary stage: Colonization

Where it fits in the grow

Inoculated from liquid culture or agar, then used to inoculate bulk substrate.

Safety & handling

Any sour or sweet smell, wet-looking grain, or grey-green patches means bacterial or mould contamination. Do not open a contaminated bag indoors — seal it, remove it, and discard it.

Practical advice

Break and shake at roughly 30% colonisation only. Shaking too early stalls recovery, and shaking too often stresses the mycelium and slows the final run.

Educational only. Mycelium Works does not sell this or any other product, and we receive no payment for listing it. Specifications vary by manufacturer — always follow the maker’s instructions and local regulations.
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