Grow Blocks 101

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Always handle your block with clean hands and use clean cutting tools. Be sure to grow on a waterproof surface in an area that can take up to 2 weeks elevated humidity. The kitchen counter or a clear plastic tote without a lid can be good choices.

Check for pests and mold. Avoid fruiting mushrooms in areas where these are a problem. As the block nears the end of its productive life, these issues are more likely to develop. Visit our page on reusing your block or add to compost.

Place your block where it will receive some light, but not direct sun. All our species grow naturally in filtered forest light. Incandescent light including grow lights work well. 

Wait, don't mushrooms need darkness?  We are often asked about growing in the dark. Darkness may cause elongated, pale, unhealthy fruits in all of our species except king oysters. Like white button mushrooms, kings are grown in dim lighting to achieve a preferred shape and color.

Research shows that mushrooms grown in UV light contain vitamin D2. You can let your mushrooms spend time outside in dappled shade before harvesting to get this benefit. You can fruit your block entirely outdoors, but the risk of pests increases. Outdoor light darkens the color of mushroom caps like a suntan. Protect growing mushrooms from drying out in sun and wind. Monitor outdoor blocks frequently for pests.

Prepare a clean spray bottle with plain tap or filtered water. Don't spray your block with anything you wouldn't eat! 

Mist the surface of the plastic bag 2 to 5 times per day depending on your home's humidity & airflow. Try to ensure there are droplets present most of the time, especially in early growth stages. Protect blocks from heat sources like radiators and wood stoves.

Water droplets on plastic evaporate to create a humid microclimate. There is no need to water the block or the mushrooms themselves, everything they need to "drink" is in the bag. Our goal is to water the air!

Timing is everything. Mushrooms require the highest humidity immediately after cutting the bag while new baby mushrooms (aka pins) are developing. Their needs decrease a bit as they mature, and lowering the moisture a bit more just before harvest can slightly increase shelf life.

Grow in regular room air. Mushrooms inhale oxygen and exhale carbon dioxide like animals do. Don't keep them where this will be restricted. You can use totes or bags to increase humidity, but make sure at least one side of your setup is fully open to air.

Mind the breeze. Too much wind can dry out your block or your harvest. Do not grow in front of fans, vents, or breezy open windows.

We guarantee at least a first fruiting on every grow block. Additional harvests will depend on following the tips above, your environment, and a bit of luck. If you have any problems or need help, contact us.

Check out our step by step gallery of directions for both top and side fruiting mushroom grow blocks 

Check out the customer gallery to see what others have harvested at home