Shiitake Mushrooms


The shiitake log, and by extension the shiitake mushroom, is our flagship product. Kennett Square Specialties leads the shiitake industry, with the capability to produce over 120,000 shiitake logs per week. Our shiitake logs are grown from a fine sawdust and mixture of grains, which provide the nutrients needed for a beautiful harvest of shiitake mushrooms. The shiitake block starts in a clear plastic bag, as a pile of loose raw materials. The substrate is then sterilized and left to cool in a clean room. Our homemade shiitake spawn is then added to the sterilized substrate. Shiitake spawn grows and knits together the raw materials over the course of about 2 weeks. We then remove the plastic bag from the shiitake block. At this stage the shiitake log is still too immature. Two additional weeks of the proper temperature, humidity, and CO2 are needed to “brown” the shiitake block. The entire process is a total of four to five weeks, culminating in a ready to grow product. At this stage, we use the shiitake log to grow mushrooms at one of our family farms, or we sell the shiitake log to other mushroom farmers. Our customers can expect a ready to grow shiitake log, of the same quality that we use ourselves.


Our shiitake blocks require temperatures ideally between 60 f – 62 f , but can get results as extreme as 54 f – 66 f. High humidity is also needed, above 80-90% is recommended. The third and final core component for shiitake logs is CO2 . We grow our shiitake mushrooms around 800-1200 parts per million CO2 . Outdoors CO2 levels are 300-500 ppm, so our shiitake logs require some ventilation but not too much. Without outside air, shiitake block grow rooms can reach levels in excess of 3000ppm.

Once proper conditions for shiitake logs are present, all the farm has to do is soak the shiitake blocks in water. Our shiitake logs work on 16 day cycles and can expect at least 3 “breaks” or “flushes.” This means that every shiitake log will produce 3 harvests of mushrooms every 16 days. Some customers report a 4th or even 5th flush of mushrooms, but we value growing space and time over the extra (less successful) flushes.

After the 3rd flush, the shiitake log can be composted, trashed, or re-soaked around day 48 in an attempt for a 4th flush. The largest harvest is 1st flush, with each consecutive flush being slightly less. Any flush attempts after 3rd may be result in little to no crops. With roughly 5,000 new shiitake logs being soaked every single day, our farms value the grow space over the small gains from a 4th flush.

The objective during soak phases is to absorb roughly 1lb of water in the shiitake block. Weighing a shiitake log before soaking, and checking its weight throughout the soak is recommended.

Harvesting shiitakes off the log is simple, just pull from the base of the stem. Don’t worry about any bits or pieces left behind on the shiitake log. Try and target shiitakes with “umbrella” shaped caps. If the shiitake cap is still tight and closed, it’s too early. On the other hand, flat wide mushroom tops is should have been picked sooner.

Our dormant stage is a required step. The shiitake log needs time to rest and dry out. The proper growing conditions still apply. Over 90% humidity should be present. The log can dry out in the same space it grows.

These numbers are slightly abstract but they are the parameters our professional mushroom growers have operated within for over 25 years. Every mushroom farm is unique, with its own traits and characteristics. Growers might needs to tweak and experiment slightly at first to get perfect results. Our shiitake logs can produce 2lbs of mushrooms, with some customers picking 3lbs in perfect conditions. KSS Sales works with all of our customers, providing support to answer all questions and help you achieve exceptional results.

Below is our affiliate farm’s schedule for growing shiitake logs:

Day 1: Soak in water 1-2 hours

Day 6-9: Harvest (1st Flush)

Day 10-15: Dormant stage

Day 16: Soak in water 4-8 hours

Day 21-24: Harvest (2nd Flush)

Day 25: Dormant stage

Day 32: Soak in water 10-24 hours

Day 37-40: Harvest (3rd Flush)

Get in touch to find out more!