Welcome to your Shiitake instructions - we're super excited to get you going.
You can get growing within three days of receipt, however, if you're not wanting to grow immediately you can put your kit in your fridge for up to one week, your mushrooms may begin to grow even when chilled so get started asap.
Equipment needed: A water mister.
Before Opening Your Shiitake kit - it’s important to check for good primordia growth – these are the first stages of mushrooms that will develop into full fruiting bodies once the kit is opened.
Your kit may need a few days to establish this growth before it’s ready.
You can see the ‘Primordial’ forming under the grow bag.
This is what where your Shiitake will grow from, and important to establish these before you open your kit.
On your Shiitake block, primordia appear as small brown nodules emerging across the surface and sides of your kit, they will begin to press on the outer bag. You want them to be 1 cm in depth before you remove the outer bag. This can take up to 7 days, during which time you can simply leave the block in a cupboard or on the side – no special conditions required.
Once your popping shiitake are a good size, remove all of the plastic grow bag from your shiitake kit, and place on a plate in a bright and light location, but out of direct sunlight to prevent drying out.
Mist your Shiitake block at least twice a day, do not let it dry out. You sent want it to sit in a pool of water, so tip away any standing water.
Ideal growing temperature parameters are 17-22 degrees. Lower temperatures can lead to slower growth and higher temps can lead to the substrate and mushrooms drying out quicker.
If you’re finding your substrate block is drying out between mists, lay a clean, damp tea towel over your block and continue to mist each day - making sure the tea towel is nice and damp too.
Your mushrooms can be seen popping from all over your kit, these will continue to grow over the next 7-10 days.
Your Shiitake are ready to harvest when the caps flatten out. Slice off the mushrooms close to the substrate block with a sharp knife or scissors.
Shiitake blocks tend fruit most of their mushrooms on the first flush. We have had occasional success trying for subsequent harvests but very often you will see a green mould beginning to form before your second flush of mushrooms appear. If this happens, compost your kit.
You can try for a second flush by submerging your block in cold clean water for 24 hours. Then place it in the fridge for 24 hours.
Lay a clean damp tea towel over your block and continue to mist each day. The idea behind the tea towel is to prevent drying out without using more plastic. You’ll need to replace and clean the tea towel frequently.
When you have finished growing: Your fruiting block should be left to dry out then disposed of into your household waste. We do not recommend composting or putting substrates into your garden, compost or food waste.
See our Instagram for images of stunning Shiitake and recipe ideas.
- x -
Congratulations and we hope you enjoy your grow. If you have any questions or curiosities please do emails us at enquiries@caleybrothers.co.uk and we'll get back to you with 48 hours.
Otherwise, do feel free to take a look at other mushrooms you might enjoy growing and eating, we have a variety of options - all delicious and all just as easy to grow.
Where to next?
→ Get our book - Project Mushroom
→Join us online at one of our workshops this autumn
→ Follow us on Substack for new posts twice a month
Happy growing x
Ⓒ Caley Brothers 2026
