Grow guide
How to inoculate a mushroom grow bag
Inoculating a grow bag means introducing mushroom spawn into sterilized substrate inside a filter-patch bag, then sealing it to colonize. Working in front of a flow hood — a workstation that blows filtered, sterile air toward you — keeps airborne contaminants out. After inoculation the bag colonizes at room temperature for about two weeks, then it's ready to fruit.
What you need
- A sterilized substrate grow bag (filter-patch)
- Mushroom spawn (grain or sawdust)
- A flow hood or still-air box
- 70% isopropyl alcohol and clean hands
Step by step
- 01Set up sterile airflowWork in front of a flow hood so filtered air moves toward you, carrying contaminants away. Wipe surfaces, the spawn container, and your hands with 70% isopropyl alcohol.
- 02Open the bag in the clean airOpen the sterilized substrate bag only in the flow hood's clean-air stream. Keep the opening facing into the filtered air the whole time.
- 03Add the spawnPour in the spawn at roughly a 1:2 spawn-to-substrate ratio. More spawn colonizes faster and out-competes contamination.
- 04Mix and sealBreak up and distribute the spawn evenly through the substrate, then fold and heat-seal (or clip) the bag closed so only the filter patch breathes.
- 05Label and incubateWrite the species and date on the bag. Incubate at room temperature (70–75°F) in the dark. White mycelium spreads over about two weeks until the block is fully colonized.
- 06Fruit the blockOnce fully white, move it to fruiting conditions — cut the bag, mist, and follow the grow steps for your species.
Common questions
Do I need a flow hood to inoculate a grow bag?
A flow hood dramatically lowers contamination and is what we use, but a still-air box is a low-cost alternative for home growers. Sterile technique — alcohol, clean hands, minimal open time — matters most.
How long does a grow bag take to colonize?
Most gourmet species fully colonize a bag in about two weeks at room temperature, then fruit within days of being opened.
Want to do it in person? We'll walk you through every step at the flow hood and you'll take home a block you inoculated yourself.