Growing Mushrooms From Spent Mushroom Compost
You’ve probably seen those mushroom kits you can buy from stores like Bunnings. Well, they’re a total ripoff. I’ve never met anyone who got a good yield growing mushrooms from them. Here’s a much cheaper way to grow your own mushrooms…
Every once in a while I take my trailer up to the mushroom farm. They sell bags of spent mushroom compost for around $3/bag. I usually fit about 16 bags of bulk mushroom compost in the trailer, and it costs a bit under $50. That’s a relatively cheap way to get a large quantity of decent compost, but you can squeeze a lot more value out of it than that!
I bring the bags of spent mushroom compost home and put them under my house where it’s dark and cool. I use a mister to spray the growing mushrooms with water every morning and night, to make sure the layer of peat on top of the compost stays moist.
The mushroom compost is not really ‘spent’, it’s just no longer producing commercially-viable quantities of mushrooms. Mushrooms will soon start growing though, and I can continually pick them for about 3 to 6 weeks. On a good day, I can get a kilo or more of mushrooms, but it typically averages about 2-3 kg a week.
Eventually, the growing mushrooms get overrun by various other types of fungus and it all turns to mush. By the time this happens, I’ve harvested 10 kg or more of mushrooms.
The thing that amazed me about growing your own mushrooms is how different they are to store-bought. Isn’t that the same for everything? Fresh-picked mushrooms are sweet and have a really creamy flesh. The difference is incredible.
So what do you do with that many mushrooms?
Well, you soon get sick of mushrooms on toast for breakfast. They’re nice on the BBQ, or you can stuff them and bake them. Or add them to salad. You can still only take so much mushroom, though.
The best way I’ve found to preserve excess mushrooms is to chop them and saute in olive oil and butter, then scoop into muffin trays for freezing. Once frozen solid, you can tip them out of the muffin trays and put them in plastic bags back in the freezer. Whenever you want mushrooms for a soup or casserole, just take a portion out and drop it in. Or you can defrost them for pizza toppings, as a garnish on steaks, or to simply serve on toast.
Oh, and once the harvest ends you still have the bags of (truly!) spent mushroom compost for the garden. It really holds water well and supplies micronutrients, although I’ve found it best to blend it into other stuff in the compost heap for a few weeks before using it. The compost is sterilised before being used to grow mushrooms, so you want to make sure it gets repopulated with microorganisms to help make your soil really healthy.