Instructions – Shiitake

Shiitake (Lentinus edodes)

Shiitake tip: The mycelium will form a brown ‘crust’ on itself to help retain moisture. If your kit is partially or entirely brown, this is in fact a very good sign.

This is a variant called S75 that will fruit in a relatively wide range of temperatures. It’s still not a fan of heat over 25 degrees. With proper care you should get 1-2 pounds of fresh shiitake from this block over its roughly 16 week lifespan.

Congratulations on your purchase of a mushroom growing kit! If you already have a tabletop humidity tent or mini-greenhouse you can use that, otherwise something can be easily improvised (or try without if it’s humid.) At home I use a 4-tier mini greenhouse that I picked up pretty cheaply.

A humidity tent is not required, but may be helpful if the air is dry in the growing area.

You will need:

– your spawn block

– a clear plastic bag or clear plastic over a frame for humidity (optional)

– a very sharp knife

The spawn block is composed of pelletized hardwood sawdust and various organic supplements such as wheat bran, held together by the white mushroom mycelium. While most blocks are received ready-to-fruit, check the date on the bag. It will say something like “SH 5/24 or S75 5/24”, meaning May 24th. If the date on the bag is less than 45 days ago, put the bag somewhere dark until 45 days have elapsed before proceeding. The browner the block is, the better. You can leave it for a decent while before initiating fruiting, up to 120 days from inoculation. 

If you can’t get rainwater or well water, you can remove the chlorine by boiling water (then cooling it!) or just leaving it out for 24 hours. Or buy a gallon jug of “mineral water” (not distilled water) from the store for a couple dollars. Or if you live on the BC coast, tap water’s probably just fine.

Take your spawn bag and slap it around a bit where it’s browned. Slap it like you’re afraid of hurting it, not like it owes you money. Open-hand. This will help it to initiate fruiting. While still in its sealed bag, put the block in the fridge for 1-2 days. Do not freeze it.  Take it out, cut the top off the bag just below the heat seal (or cut the zip tie off, if it has one.) At this point, try to pick any small mushrooms growing off the block, if they’re present, before soaking. Fill the bag 1” over top of the block with cold water (well water or rainwater ideally, but tap water is not the end of the world), and soak it for 3-4 hours. Don’t use warm or hot water! Check on your bag after 15 minutes or so, it may have soaked up a lot of the water. After it’s soaked, pour the water out of the bag and carefully cut the bag away from the block. Gently place the block on a plate or pan, and put the humidity tent over it.

Put the block somewhere with indirect light (not in a sunny window!), and lift the humidity tent (if using one) to mist it 2 or 3 times a day. When mushrooms are growing, try not to spray water directly on the mushrooms themselves. As long as the air is humid and there’s not water directly on the mushrooms, there’s no such thing as too much spraying or air exchange.

You should start to see small fruits forming within a week or so of starting the bag. If not, don’t panic, shiitake can take a little longer, as long as it has good conditions, it’ll fruit when it’s ready.

When the block has finished fruiting (no new fruits form for 7+ days), remove the humidity tent and let it dry out for a week. Be sure to keep it safe from insects during that time. Poke a few holes in it with a clean skewer, dunk it for a few hours in cold water, and repeat the process. You may get up to 3 or 4 harvests.

If the block develops heavy colourful mold or bacteria (which is rare when kept in a clean environment), do not eat the fruits from it after that point and dispose of it away from other mushroom projects. This happens more frequently with blocks at the end of their lives. Due to the possibility of non-harmful but unsightly fungus gnats, it is not recommended to keep the block in the same greenhouse as potted plants.

If contamination develops, go here for tips!

If you have any problems or questions, please don’t hesitate to e-mail!

Mushroom growing can be challenging and while, due to the number of factors involved in getting a successful harvest, we don’t offer a guarantee, help is most certainly available.