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Organic Shiitake Mushroom Grow Kit Fruiting Block










Skill level | Intermediate |
Grow location | Indoors |
Grow speed | 1.5 to 2 weeks |
Kit shelf life | 6 months (refrigerated) |
Kit dimensions | 6in H x 9in W x 6in D |
Kit weight | 5 lbs |
Fruiting temps | 55-70°F |
Our Shiitake (Lentinula edodes) fruiting block features a popular strain that produces light brown, medium-to-large, umbrella-shaped caps. Shiitake mushrooms are a delicious edible fungus from East Asia and their flavor is described as rich, savory, buttery, and umami. This strain tends to produce generous flushes, making them a great mushroom for confident beginners and intermediate growers.
Shiitake are reliable producers as long as the ambient humidity in the growing environment remains consistent. Because the block is removed entirely from the bag once it's ready to fruit, shiitake blocks are prone to drying out. Therefore, we recommend using a humidity tent or humidity-controlled fruiting chamber (like a monotub or martha tent) to help mitigate the moisture issue.
"5 of the Best Shiitake Mushroom Recipes"
Upon receiving your kit:
Remove kit from the shipping box as soon as possible. Then, unfold the top of the bag, making room for air space. It's also important to check and confirm that the filter patch is not obstructed. This will help the organism breathe and continue to thrive until you are ready to grow your fruiting block!
Scroll down for guides on growing, storage, cooking, and more.
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For the majority of mushroom species, all that is needed to initiate fruiting (or begin the growth cycle) is a change in environmental conditions -- specifically humidity, light, temperature, and changes to oxygen and CO2 levels.
For best results:
We recommend growing your shiitake block in a fruiting chamber (like a monotub or martha tent) as a controlled environment will decrease the risk of contamination and increase the chances of success.
Creating optimal conditions:
The environmental parameters for shiitake can be found on this page under "Temp, Humidity & CO2 guide" and on page 13 of our fruiting block instruction booklet.
Preparing your block:
Your shiitake block should be given time to brown in its bag at room temperature before fruiting is initiated.
How to initiate fruiting:
- Once the block is mostly brown, place the sealed block in the refrigerator for at least 48 hours.
- Next, remove the block from the bag and soak the block in cold water for approximately 4 hours before placing it directly into your fruiting chamber.
- DO NOT place back into the bag, as shiitake blocks grow without a bag.
Special considerations:
Shiitake can be prone to Trichoderma (green mold). If you see green mold, spray affected areas of block with hydrogen peroxide 3%.
Harvesting your mushrooms:
Harvest your shiitake block just before the caps flatten. Trim flush with the block so no stem remains on the block before subsequent fruitings. Place block back into fruiting chamber between fruitings to prevent it from drying out and to decrease risk of contamination.
Growing different blocks together:
With some compromise, many different species of mushrooms can be grown together in a fruiting chamber. First, consider the temperature range of the mushrooms you desire to grow, and second, the CO2 sensitivity. Humidity ranges overlap for the majority of species. We encourage you to experiment with many different groupings!
Troubleshooting:
Having issues with unusual growth, stunted growth, or no growth at all? Refer to pages 16-18 of our fruiting block instruction booklet.
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Temperature 55-70°F | 13-21°C Humidity (Phase 1: Primordia) 95-100% Humidity (Phase 2: Fruitbody) 85-95% CO2 Sensitivity (Phase 1: Primordia) 500-700 ppm CO2 Sensitivity (Phase 2: Fruitbody) <1,000 ppm - Primordia - The earliest recognizable stage of fruitbody development. Also known as “baby mushrooms” or “mushroom pins.”
- Fruitbody - A fully grown mushroom, the reproductive structure of the organism in which the spores are produced.
- CO2 sensitivity - When CO2 levels are too high, yields will decrease, stems will become long and stringy, caps will be small, and/or growth will halt.
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If you don't plan to use immediately, you can refrigerate your block for up to 6 months.
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"5 of the Best Shiitake Mushroom Recipes"
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.
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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.
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- Reviews
- Questions
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Your input is very much appreciated. Share it with your friends so they can enjoy it too!

Halted growth
After waiting for almost a week before opening the fruiting bag, I opened the bag and followed the instructions. The shiitake started to grow. However, after about 2 weeks, the growth stopped and no new growth after that. I kept the fruiting block in a plastic tub and kept the humidity between 85-90%.

Shitake
The venerable Shitake. Loving these mushrooms!

Quality supplies
I have found North Spore’s work fruiting blocks to be of high quality. They are yielding a number flushes, if you use the right environment.

How Sinai fix this?
I’m giving a five star rating because the issue has been with our atomizer. However we are not getting any pi’s on this shuttle block. I followed the steps very carefully as this is my FIRST time growing shiitake. I would love some help as to how and what we need to do to correct this. I love all my North aspire buys thus far. Just having a tiny issue here. Please HELP! Thanks for reading!
North Spore
Hi Dani, We would love to help! If you email info@northspore.com and describe the issues you are having, somebody from our customer care team will be able to assist you:-)

This was a gift!
My friend is loving this as I knew she would. They are just starting to grow and she is so happy!!

Awesome blocks!
With proper humidity and temp, these blocks POP! Pictures speak for themselves!

Giant Shitake
Wow, a 3 inch wide shitake from a second flush! North Spore does the hard work for you. The blocks come to life with ease. No need to wait for months to colonize a bag, or a year to colonize a log. Just pop the block out of the bag and let them grow!
North Spore
Wow!Those shiitakes look amazing :-)

Shiitake block pops off in a week
The Shiitake block has been a very positive “first try” experience. I followed the directions and “boom”, Shiitakes. Lots of them. I’m making miso soup with some today. It was entertaining to watch the growth cycle and speed from pins (Tuesday) to harvest (Saturday).
North Spore
Those shiitakes look great!

Best Shiitake Blocks!
I followed the directions and grew this huge, beautiful shiitake mushrooms! The first flush just kept going, too. I picked the larger cape to make room for the smaller ones. On my second flush now!

Great first time shitake!
The block was beautiful when it arrived. A cold dunk after refrigeration and BAM! PINS! I've never seen so many in such a small space! I'm used to logs and this was 1000x better! Great product!