Wait to start growing your block until it has turned mostly brown before opening the bag to begin growing (See photos in carousel for reference). 

Your shiitake fruiting block kit is an amended sawdust block that has been completely colonized by mycelium. Once the block is mostly brown, place the block (still inside the unopened bag) in the refrigerator overnight. The following morning, remove the bag from the fridge, remove the block from the bag, and discard the plastic bag.

Next, soak your block in cold water for four hours. As it will want to float, you may need to place something heavy (like a pot or pan) on top of it while it soaks.

Next, remove the shiitake block from it's cold water bath and place it on a plate. Shiitake growing requires proper humidity and ventilation to survive. Place your block in the most humid part of your home and away from direct sunlight. (We recommend putting your block on a kitchen counter somewhat close to a sink)

In the winter months, or if your home is really dry, you may want to make a humidity tent to place over your block. Simply take a trash bag or other loosely fitting plastic bag and put plenty of ½-inch holes in it. (This is important: Mushrooms exhale CO2 and inhale oxygen. They will suffocate themselves if there isn’t adequate airflow. If you see shiitake mushrooms growing strangely or having unusually fat stems, it’s usually because they need more air.) Spray the outside of your block at least once per day until the block forms baby mushrooms (called “pins”).

Harvest your mushrooms when they resemble the ones in the photographs. Harvest before the caps flatten out and become soft or soggy. Growing shiitake mushrooms can happen quickly, so when you spot your first mushroom pins, keep a close eye on them. The warmer the environment, the faster shiitake mushrooms will grow. Mushrooms should be ready to harvest 4 to 10 days after pin formation.

When growing shiitake mushrooms, you can expect one harvest, but you may choose to attempt a second fruiting off your block. Harvests usually diminish in size with each consecutive fruiting. We recommend giving your block a one-week break from spraying and then soaking your block in cold water for 20 minutes and restarting the process of spraying your block with water daily.

If you don't plan to use immediately, you can refrigerate your block for up to 6 months.

Shiitake has a meaty texture when cooked and is good for drying and reconstituting in winter soups. It pairs beautifully with tamari, ginger, and garlic and can bring needed umami to many different dishes. These mushrooms are delicious sauteed and can be used in stir-fries, risottos, ramens, on pizzas, or simply eaten by themselves.

Spawn used in our fruiting blocks is grown on USDA certified organic grain and made with organic cultures from our own culture bank. Our fruiting blocks are handmade from a blend of locally sourced, all-natural, organic, and non-GMO woods and supplements from farms and forests in New England and North America.

If your home is really dry you may want to make a humidity tent to place over your block. Simply take a trash bag or other loosely fitting plastic bag, put PLENTY of 1/2 inch holes in it. (THIS IS IMPORTANT mushrooms exhale CO2 and inhale Oxygen. They will suffocate themselves if there isn’t adequate airflow! Shiitakes that look strange or have unusually fat stems are usually growing that way because they need more air!) If you choose to use a humidity tent make sure to spray the inside of the tent once per day to maintain humidity.

If you’re going to consume home-grown mushrooms, make sure to cook your fresh mushrooms thoroughly with heat. If it is your first time eating this species, it is best to start with a small amount to check for allergies, even if cooked.

Mushrooms grow spores as they develop. This is a natural means of reproduction. This is when people with allergies or compromised immune systems may want to consider putting fruiting mushroom kits outdoors or in a well-ventilated area. Spores in mushrooms sometimes cause respiratory irritation. In rare cases, spores may also cause irritation for some non-allergic or non-immunocompromised mushroom growers. If you are one of them, it is recommended to reduce the overall spore load by harvesting mushrooms while they are still in their younger growth stages.

Fruiting Block Kit FAQs

Martha Tent Set Up & Grow Guide