Urban Mushroom Farming

Back in 2012, when hurricane Sandy hit the Northeast, I wondered how to use some of the devastation, how to make something with all the broken trees. I don't have a wood shop or even a car, but it occurred to me it might be easy to inoculate the lumber with mushroom spawn. You don't need a lot of space to grow mushrooms: any shady backyard or alleyway will work. You might even be able to grow them indoors, but you will need to put the logs where you can hose them down.

As with most projects it turned out to be a bit more complicated than I had anticipated. After dragging a few limbs home, I realized that I needed thicker branches, and that I had the wrong type of wood. Most of the downed trees in my neighborhood were Honey Locust, Bradford Pear or London Plane, but Oak is the best type for most tree mushrooms.

To make a long story short, a generous arborist at the Botanic Garden provided me with a half dozen huge oak logs, and a very kind motorized neighbor and fellow mycological enthusiast helped me lug them home.

It was the beginning of a very slow adventure.

Thick logs are better for several reasons: first, growing fungi need moisture, and the thicker logs will not dry out as easily. You will also be inoculating your logs with 3/4″ wooden plugs, which need to go into the outer sap wood (the lighter ring right underneath the bark). The fungus won’t grow as well in the inner heart wood, so you want the inner sap wood to be at least 3/4... which means your log should have a diameter of at least 10-12 inches.

I ordered my spawn from Fungi Perfecti. They come as wooden plugs covered in white sticky material, carefully sealed in plastic. I got several varieties (shiitake, oyster, but also lion's mane and chicken of the woods). You only want to put one type of mushroom into each log so they don't have to compete with each other.

The ideal type of wood and age of the log depends on the type of mushroom you want to grow. The mushrooms I chose do best on a clean, fresh log from a tree felled a few days (or a couple weeks) before inoculation. A good vendor will have information and instructions specific for each variety of mushroom they sell.

Drill small holes into your log just the right size so the plugs fit in snuggly. Drill holes about 2-3 inches apart, all around your log. Mark your drill bit with a piece of tape so that the distance from the tip of the bit to the tape is the same as the length of the plug. When you drill your log up to the tape mark on your bit your holes will be just the right depth. With clean hands, push the plugs with the delicate fuzzy white growth into the holes. Use a (clean) rubber mallet to push them all the way in if necessary.

You are supposed to seal all the plugged holes and the ends of your logs to make it harder for wild (and probably inedible) fungi from taking over and colonizing your log.

When I first attempted to seal the holes, I used a paintbrush to spread melted beeswax on the plugs, but this got tedious and messy, plus it was hard to keep the beeswax liquid long enough -- so instead I used a regular candle, lit it, and dripped the wax on the plugged holes. I did use the paintbrush to seal the end of the log.

It turns out this was mostly useless... maybe I just didn't do it well enough, or use enough wax, but after a few months of the wood expanding and shrinking with humidity variations, there was clearly no proper seal... and sure enough a variety of wild and inedible mushrooms found their way in to feed on the tasty oak. It was OK though, because according to my mycologist neighbor the particular varieties of wild fungi sharing the log were not the ones which would harm the edible ones. I believe the uninvited guests were mostly Turkey Tails, and King Alfred's Cakes... but if there's a specialist out there who can identify them better, please comment!

It is best not to lay the logs directly on the ground. Though the moisture is good, you're trying (in my case, unsuccessfully) to keep them from getting contaminated with wild strains of fungi. I used some spare branches I found, but in retrospect it would have been better to use cinderblocks. I think some fungi travelled from the ground to my supporting branches to my oak logs.

The two most important things in terms of care are water and shade. The logs need to stay moist, and it can take many months, or even a year (or two and a half, in my case) before you see any mushrooms -- so an automated watering system is pretty useful -- but if you're able to water them with un-chlorinated water (rain water or well water) that's better than tap water. I didn't have that option, which might explain my slow results.

I placed my logs in the shadiest spot of a narrow strip of land behind my apartment building, and hooked them up to an automatic drip irrigation system, so they were watered twice daily from late Spring to early Fall. I inoculated my logs in the Fall of 2012 on and my first flush of shiitake mushrooms appeared in May 2015.

Apparently you CAN force the mushrooms to come sooner (a few months after inoculation), by soaking them in un-chlorinated water for 24 hours (leave the tap water in your bathtub overnight to get rid of the chlorine). I opted not to go that route because I wanted to see how long they would take on their own. This was probably another mistake: I gave all the wild fungi more time to join the party.

By the time the mushrooms arrived 2 and a half years later, I had given up hope, so I was excited beyond belief when I saw little baby mushrooms poking through the bark. Be extra vigilant to keep your logs moist at this point, otherwise your babies will dry up and stop growing.

I got several flushes -- two in the Spring, another in the Fall -- and two varieties of mushrooms. Shiitake and Oyster. The Shiitakes in particular were delicious, much better than the ones from the supermarket (and I don't think this opinion was influenced by my being predisposed to enjoy them).

Conclusion

If you're strictly looking for results and cost effective mushrooms you will be better off just buying a pint of mushrooms at the supermarket. If you enjoy experimenting and watching things grow, this is for you. For me this was a very fun, long term project, and I will try it again (correcting for past mistakes) next time I can get my hands on some good logs. I'll update this Instructable if and when I do, so subscribe to me if you're interested!