What to do with Leftover Mushroom Spawn?

Now that we are entering spring and the mushroom frenzy season, we get the occasional call from growers asking what they can do with extra spawn. If you find yourself in this position, you have options depending on what type of spawn you have. Here are a few suggestions from us on what to do to make the most of that extra spawn.

King Blocks

1) Use it! Inoculate heavy

Our first suggestion is to use the spawn up - even if that means drilling more holes into your already inoculated logs and adding more spawn. More spawn = faster colonization! Who wouldn't want mushrooms faster?

2) Use it! Get more logs, straw, or materials to plant

Could you get more logs to use up that spawn? Or pasteurize more straw for that extra oyster grain spawn? If you can get more, you'll have more mushrooms. If you can't get more logs or don't have the time to do so right away, then that brings us to your third option: save the spawn to use later.

3) Save it for later.

Almost all of our spawn varieties can be stored in the refrigerator for later use (*Pink Oyster and Almond Agaricus are the only exceptions to that - keep these at room temperature). Place unopened bags of spawn in the refrigerator, but be sure they will not freeze. Opened bags of spawn can also be stored in the refrigerator, but be careful the spawn does not dry out by removing extra air within the bag, folding down the top, and even putting it in a Ziploc bag. Plug spawn stores very well and can be used up to 6 months after refrigeration! Grain spawn can be stored 1-2 months. Sawdust spawn can be stored for several months too, although sometimes mushroom fruiting can occur on the spawn, even if it is stored in the refrigerator.

4) Use it! Experiment a little

There are all sorts of things you can do with extra spawn. We've experimented a lot, and we hear our growers like to experiment too! Here are a few other ways to use up your extra spawn.

a) Make cardboard spawn for inoculating totem logs

Many mushroom varieties can be grown on logs using the totem method. If you don't have enough sawdust or grain spawn left to inoculate a totem, of if you have plug spawn which doesn't work well to inoculate logs this way, then you can use the leftover spawn to make cardboard spawn. Simply soak the cardboard for several hours in water. Pull the cardboard out of the water and allow the excess water to drain off. If you can, peel the cardboard apart to expose the corrugated interior - sprinkle your spawn here and then place the top layer of cardboard back down so the spawn is sandwiched in the middle. Roll this cardboard up and slip into a plastic bag and store at room temperature. The mushroom mycelium should start to spread from the spawn throughout the cardboard. When the cardboard is covered with white mycelium, these pieces of cardboard can be used in place of spawn to inoculate a totem. See Oyster on Logs, Shiitake Totem, or Lion's Mane instruction sheets for more information on constructing totems. If your mushroom variety is not grown on logs (Wine Cap, Almond Agaricus, Blewit), then the cardboard spawn can also be used to plant mushroom beds. In fact, cardboard spawn can be used to plant many different substrates if you are in the mood to experiment!

b) Make your own ready-to-fruit blocks!

As we said, not all mushroom varieties grow well on sawdust blocks, but if your spawn is Oyster, Lion's Mane, Comb Tooth, Reishi, Chestnut, or Shiitake, you can make your own mushroom fruiting blocks. We have a method using wood fuel pellets can mix up your own recipe (there are so many resources and recipes available online). Sawdust spawn, grain spawn, and even plug spawn can be used to inoculate the blocks you make. If you are new to making your own blocks, we recommend you use a heavy inoculation rate (think at least 1 cup of spawn per block). The mushroom's mycelium will spread from each bit of sawdust, grain kernel, or plug spawn into your block until the entire thing is colonized and ready to fruit. This process can be more advanced for the average grower, but well worth the effort if you are successful!

c) Build a castle with Reishi bricks.

Well, maybe not a castle. But some engineering folks are using Reishi mushroom substrate to build things. We've seen bowls, chairs, hats, and even a canoe. We aren't engineers here, and maybe you don't have enough leftover spawn to do this, but we think this is a pretty cool use. For a more simple reuse, you can build a border for garden beds with old Reishi blocks. This way you have a nice neat border as well as some extra Reishi!

5) Give it away!

Give the gift of your mushroom growing obsession to a loved one (or that weird neighbor down the road, whoever you want). Growing mushrooms is fun for everyone! We have instruction sheets available online if they are new to growing mushrooms, and we are happy to get them started using your extra spawn.

6) Compost it. Mushroom compost = the best kind of compost!

Lastly, but certainly not least, you can simply add your extra spawn to your compost pile. Chances are good you will get some mushrooms fruiting from that, but it will also add an extra boost to your compost and make it better than ever when the time comes to spreading that out in your garden. Mushrooms are healthy for us, and they are also healthy for your soil and garden veggies. We're not making this up - we're doing actual research on this, for real! (See our SARE Series research page!)


Above Uses:
1: Buried King Oyster spawn- bury it in the summer and it will produce in fall.
2: Garden bed border- we used our "spent" Reishi blocks to create a garden bed border. Not only did it contain our bed, but it also produced bonus Reishi!
3: Extra pink grain spawn? Experiment! Oyster mushroom grain spawn can be grown in a variety of different mediums.