Instructions - Grow Block Kit - Reishi

How to activate kit!

Reishi grow very slowly. Depending on your needs, you can harvest your kit early when the mushrooms resemble deer antlers. Or, you can allow the mushrooms to stay in the bag for a few months longer to form more interesting shapes. You can also try to get mature mushroom caps, which requires more supervision and bag opening (as described in the instructions section below). This is a more challenging method, but can be very rewarding for those who have previous experience with Reishi kits.

If you are interested in growing your Reishis into "deer antlers", a fruiting chamber is not necessary. However, if you are interested in growing hats, we recommend growing your Reishi block in a fruiting chamber (such as a monotub or martha tent), as a controlled environment will reduce the risk of contamination and increase the chances of success.

For "Deer Antler" Reishi, there are no special parameters (since the entire growth cycle occurs inside the bag). Instead, the environmental parameters for developing the hats are found on this page under "Guide on temperature, humidity and CO2".

Block Activation:

Lift the top of the bag, making room for air. Check and confirm that the filter is not blocked.

How to start fruiting:

For the "Deer Horns":

DO NOT open the bag. Reishi needs the high humidity and CO2 environment of a closed bag to form horns. Place the closed bag in a place with light and ambient temperature, away from direct light and heat sources, until you are ready to collect it. This process can last several months, on average about 3 months, sometimes even longer.

To develop hats:

DO NOT open the bag until the antlers are approximately 15cm tall. Once you have passed this height, make a cut of about 10 at the top of the envelope. Place the kit in a fruiting tent and harvest once the caps have developed and spore production has begun.

Special Considerations:

Reishi mushrooms grow very slowly. Due to the slow growth rate, there is a greater risk of contamination when the bag is opened and placed in a fruiting chamber.

Harvesting your mushrooms:

To collect the mushrooms, turn them at the base and then clean the substrate residues. Dry them in the open air or with a food dehydrator

Guide to temperature, humidity and CO2

Temperature: 18-26Β°C

Humidity (Phase 1: Primordia) 95-100%

Humidity (Stage 2: Fruiting body): 85-95%

CO2 (Phase 1: Primordia): High CO2, keep in bag

CO2 (Phase 2: Fruiting body): <2,000 ppm | keep the bag closed for the deer antlers, open the bag for the hat to develop

Primordia - The earliest stage of fruiting body development.

Fruiting body - A fully grown mushroom, the reproductive structure of the organism in which spores are produced.

CO2 Sensitivity - When CO2 levels are too high, yield will decrease, stems will become long and stringy, caps will be small, and/or growth will stop.


If you don't plan to use your Reishi kit immediately, store it in the refrigerator for up to 6 months. If left at room temperature, it will continue to grow.


Reishi mushrooms are intensely bitter and woody and are not usually considered culinary unless they are harvested very young. However, we recommend adding a slice or two of dried Reishi to the broth, as you would a bay leaf, to infuse the broth with its medicinal properties. You can also choose to incorporate Reishi into medicinal teas and tinctures.

Attentions and considerations

If you plan to consume home-grown mushrooms, be sure to cook your fresh mushrooms thoroughly. 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 produce spores during development. This is a natural means of reproduction. This is when people with allergies or compromised immune systems may want to consider placing fruiting mushroom kits outdoors or in a well-ventilated area. Fungal spores can sometimes cause respiratory irritation. In rare cases, the spores can cause irritation even for non-allergic or non-immunocompromised growers. If you fall into this category, it is recommended to reduce your overall spore load by harvesting mushrooms while they are still in their youngest growth stage. Reishi will only develop spores once the cap has formed.