Your spawn will arrive in a Polypropylene bag with a breathable filter patch.

The bag will be close to fully colonized, to allow you to witness the last stages of colonization. When the white mycelium has covered most of the substrate in the bag, use your hands to crumble the contents of the bag, then shake it loosely back together. Here's a bag I've just crumbled.

Leave it for a day, then use it to inoculate your chosen bulk substrate, or try making more spawn. As a general rule, the more spawn you add to your bulk substrate, the better. You can leave the bag for a week, then cut the top off and allow the bag to fruit. If you notice mushrooms forming in the bags, you can cut holes to allow them to grow out of the bag.

This is the first flush from a small bag. Substrate was eggshells, carrot pulp from juicing, coir, rolled oats and gypsum.


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 After one or two flushes of mushrooms, you can crumble the remaining contents and use them to inoculate more fresh substrate.

Here is an old King Oyster spawn bag. Cut off any remaining mushrooms, and remove any dodgy looking bits. Below, you can see I'm crumbling the used spawn bag into a larger bag. The larger bag contains the following substrate-1 block of coir with water to make about 60 litres (I mix it in a garbage bin), 200 gms gypsum, 100 gms sugar, 200 gms of used cooking oil, 500 gms of spent coffee grounds, and 100 gms of "Aware" clothes washing powder.

I Like these bags because they allow gas exchange, while providing protection against insects and other pests. People use garbage bags, buckets, trays, and even trenches in the garden...find what suits you.

Mix the contents around with clean hands, or gloves, and allow to colonize-about 2 weeks.

I'm using these bags to get a harvest of mushrooms, then I'll take them to my garden and mix them with straw and woodchips in a 30cm trench. Outdoor harvests are more random and subject to your local conditions, but still worth the effort.