Organic Blue Oyster Mushroom Fruiting Block

$29.99

Our Certified Organic mushroom fruiting blocks make growing your own mushrooms easy. Designed by mycologists and colonized to the perfect level, all you have to do is create the right environment and fruit your mushrooms.

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In Stock. Ships in 2-5 business days.

Our blue oyster (Pleurotus ostreatus) fruiting blocks feature a strain that produces beautiful clusters of mushrooms with bluish-gray to brownish-gray caps, depending on lighting conditions. They have a rich umami flavor and a soft meaty texture that lends itself to most recipes. Blue oyster mushrooms are great for beginners as they are reliable producers and tend to grow large flushes. They are also one of the easiest blocks to get subsequent fruitings and, if kept in the right conditions, should reliably produce a second flush or more!

Receiving and Storage

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!

Fruiting blocks should be used within 1 week of receipt. If you don't plan to use immediately, you can refrigerate your block for up to 6 months.

Growing Instructions

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 fruiting 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:

You can find detailed instructions for each species in our fruiting block instruction booklet.

Preparing your block:

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.

How to initiate fruiting:

  • Make a small (2-3”) cut at the top of the bag under the top seam and place upright in your fruiting chamber.
  • Allow the block to pin within the bag.
  • If slow to pin, place the bagged block in the refrigerator for approximately eight hours before returning to the fruiting chamber.
  • Once pinning has occurred, cut off the top of the bag, leaving sidewalls approximately 4” taller than the block.
  • Return to fruiting chamber until ready to harvest.

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 in our fruiting block instruction booklet.

Temp, Humidity, & C02 Guide

Temperature55-75°F  |  13-24°C
Humidity(Phase 1: Primordia)95-100%
Humidity(Phase 2: Fruitbody)85-95%
CO2 Sensitivity(Phase 1: Primordia)<1,000 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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Frequently Asked Questions

Fruiting block kits are mushroom grow kits, but tend to be larger (5 lbs) and some require a bit more care depending on species. Instead of boxes, they are bagged. We recommend growing them in a fruiting chamber such as a monotub or martha tent set up like our BoomRoom. A controlled environment will produce the best results for the fruiting blocks. And, since these kits are slightly larger, they can produce more mushrooms than our Spray & Grow Kits.

Oyster mushrooms and lion's mane mushroom fruiting block kits are great for beginners because they are reliable producers and require the least amount of effort. Reishi is also great because the mushroom grows in the unopened bag (no special care or fruiting chamber required!)

All kits should grow a minimum of one flush of mushrooms, but with a little patience and skill you can often get a second or third flush depending on the species! After you’ve harvested your first flush of mushrooms, remove any growth from the block and follow these instructions:

⮕ If you have a martha tent or an automated fruiting chamber, leave the humidity and fan running and wait about 2 weeks for new pins to begin forming.

⮕ If you are using a monotub or non-autmated fruiting chamber, open 2x daily and spray blocks generously with water. Try not to expose the blocks for too long to decrease chances of contamination.

⮕ If you don't have a monotub, martha tent, or fruiting chamber cover the block with a humidity tent made from a large plastic grocery bag with LOTS of small, quarter-sized holes. Remove the humidity tent 2x daily and spray blocks generously with water.

Be patient: It's totally normal for it to take longer for mushrooms to appear with each subsequent fruiting. However, if there's no progress after two weeks, it’s a good idea to soak your block.

Soaking your block: Take your block out of the bag and soak in a bowl of cool water. Most species only need to soak for 20 minutes. However, only soak your lion's mane block for 5-10 minutes as these blocks tend to break apart if soaked for too long. After soaking, let the block drain by leaving it cut side down for another 10 minutes or tip it around to let extra water run off. You don't want to leave standing water in your bag, so pat your block dry with a towel before placing it back in the bag.

Note: Shiitake blocks should not be placed back in the bag.

For most species, you should leave the block in the bag for the entire duration of the growing cycle. However, there are some exceptions.

⮕ Shiitake should be removed from the bag before going into the fruiting chamber.

⮕ Nameko should have most of the top of the bag cut off (leaving about 4" of plastic above the block) before going into the fruiting chamber.

Our fruiting block kits are made fromsawdust blocks that have been ammended with substrate supplements.

Cluster of brown-capped mushrooms with long, light-colored stems against a white background.

Backed by Our 100% Grow Guarantee

Every kit comes with our 100% Guarantee: You’ll get your first flush of mushrooms, or we’ll make it right. With over 350,000 happy growers, North Spore is trusted by hobbyists, chefs, and mycologists alike.

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