King Trumpet Mushroom Jumbo Grow Kit Instructions


King Trumpet Instructions

*King Trumpet goes by many names. You may hear us refer to it as "King Oyster". This is the same mushroom!*


There will already be a cut in the top of the grow bag when you receive it. This cut allows the air out of the bag so we can pack it, and allows in a little fresh air to trigger fruiting.


These kits are not grown in the box, it is just for shipping. They do not include a humidity tent as the bag performs that function for them. They do include a mister.



  • Growing temperature: 50-68 degrees. They prefer the lower end of that scale. Any higher than 68 and they will not grow. They are a cooler weather variety. 
  • Lighting: Normal indoor lighting is fine, they’re not picky about lumens or UV. Most of our customers put them on their kitchen counter. Turning the light off at night is not an issue. Also make sure they aren’t in direct sunlight. This increases temperature for them and can cause other issues as well.
  • Without opening the bag, scratch or otherwise “rough up” the top surface of the grow block.  


  • In about 2 weeks you’ll begin to see the baby mushrooms AKA pins form. There may be a ton of them or there may be 10-15 or so. Either way, the yields end up about the same as some mushrooms abort and don’t make it to full maturity. Fewer of them just mean the ones that remain will be larger.
  • You shouldn't have to mist too much in the pinning stage with the bag still up. Maybe once a day unless you live in a dry climate. You have to adjust yourself and the goal is to try to maintain the humidity level (maybe ever so slightly more) the bag came with inside. When we make the bags, we blend in the perfect amount of water to the substrate. When you roll down the bag, you need to mist more to maintain that humidity. Also keep in mind that you aren't imitating a rain shower (like with growing plants) you're imitating ambient humidity.


Post pinning care

  • Once the mushrooms are about an inch tall, open up the top seam of the bag and roll down the bag into a sort of “collar” as shown in the video. This will protect the mushrooms from any breeze or draft and make them reach up for height and ultimately better yield.
  • At this point you should be misting 3-5 times a day, about 5-10 pumps of the misting bottle each time. Be sure not to soak the mushrooms, you want to create more of a humidity effect, not actually “wetness”. Spraying the inside of the collar of the bag works well for this.
  • Don’t coop them up in a cabinet or elsewhere with stagnant air. Mushrooms breathe oxygen like we do! They need plenty of open air after pinning (baby mushroom forming) to grow properly. Avoid direct drafts like fans and vents. They can cause drying.

Harvesting and starting new harvest

  • Once the mushrooms caps have grown significantly and are beginning to upturn, showing the gills, they are ready for harvest. The mushrooms will stop growing and caps will start to flatten as they age. This is when you want to pull them. 
  • Just grab the mushrooms and pull them right off with a slight rocking motion. 
  • To start the subsequent harvests remove the white mycelial mat from the top fruiting surface, mist it heavily, and begin again by taping the top seam back together. Subsequent harvest can take a few extra weeks so patience is key :)

Storing your harvest

  • King oyster mushrooms are best kept in a paper bag or breathable container in the fridge. They keep up to two weeks in the fridge.
  • Don’t wash the mushrooms! If any substrate happens to get on them just brush them off. Washing leads to water logged shrooms :( .Indoor grown mushrooms are safe to consume without washing!
  • These guys are freezable from fresh. No need to sauté before freezing. Store them in airtight containers in the freezer. 

Happy growing!