Commercial Oyster Cultivation


In some circumstances we may be able to provide Oyster “grow blocks” for commercial/large growers.  Minimum order is 200 grow blocks.  This is in conjunction with Windy View Acres Farm in Southern Ontario.

Strain is Pleurotus ostreatus var. Grey Dove

Minimum order is 200 grow blocks.

Contracting and pricing: to be arranged.  Our role would be as a broker .  Call Bruno at 416-402-9755.



The Tree Oyster Mushroom, Pleurotus ostreatus var. grey dove

This mushroom is known by many names including tree oyster and brown oyster.  It is a flat, shelf-like mushroom.  In nature this species is found in the temperate and tropical forest from spring through late fall.  It is a grayish brown color and the cap margin is smooth and undulating like an oyster shell.  Flesh is thin-ish and delicate. Its natural habitat is broadleaf hardwoods especially cottonwoods, oaks, alders, maples, aspens, ash, beech, birch, elm, willows, and poplars.  Also occasionally found on composting bales of straw and, in Mexico, on the waste pulp from coffee productions. 

Methods of cultivation

On logs or stumps outdoors.  Inoculate in the spring and production begins the following spring or fall.  Poplar yields are good and hardwoods of greater density take longer to produce by may sustain production for longer. See the sheet on Outdoor hardwood inoculation for Shiitake to get hardwood log inoculation information and instructions. 

Indoors on agricultural and forest waste products including straw (wheat, rye, oat, rice, and barley straw), cornstalks, sugarcane bagasse, coffee pulp, banana waster, cotton waste and cottonseed hulls, hardwood sawdust (various species of hardwoods), soybean waste, and hemp waste.  pH should be 7.0 – 8.0 and fall to an optimum of 5.0 at fruiting.  Mineral and other supplements can be added to the substrates to achieve this.  Very high biological efficiency has been reported for oysters grown on coffee pulp and wheat straw.  Yield potential is 75 to 200% biological efficiency but is greatly affected by the size of the fruit-bodies harvested and the number of flushes orchestrated.

Recommended containers for fruiting include: mega-bags, regular (2.5 kilos) size bags, trays, racks, and columns.

Harvest hints:  mushrooms should be picked when young, and preferably in clusters.  Once the gills sporulate heavily/produce large amount of spores the storability declines rapidly.  Workers should wear filter masks effective down to 7 microns to eliminate inhaling spores.  Mushroom surfaces should be slightly dry at harvest and the mushrooms should be chilled to 35◦ F and then placed into end-user containers.  To avoid over-handling it is best to place the mushrooms directly into end-user containers (cardboard boxes) and then chill but this will take more space in the cooler. 

Both fresh and dried mushrooms can be sold to market.  Waste straw substrate (‘spent substrates after mushrooms have been harvested) have been test marketed as a cattle feed. 

The following parameters apply to Pleurotus ostreatus var. grey dove, which is what we supply.  Other species of Oyster mushrooms tolerate different temperatures, humidity, and air exchanges.  

Spawn production

Substrate choice for spawn: hardwood sawdust spawn for outdoor inoculation and grain (rye, wheat, milo, sorghum, corn and millet) spawn for indoor cultivation (transfer to final substrate)

Sterilization in an autoclave or ‘retort’

Bags – autoclavable bags with filter patches

Introduction of mycelium into sterilized substrate/media should be done in a ‘clean room’ to avoid massive contamination

Parameters and conditions for spawn maturation

Temperature: 75F (24 C)

Relative humidity: not important as spawn is in sealed bags 65% is sufficient

Duration: 12 – 21 days

CO2: 5,000 – 20,000 ppm

Fresh air exchanges: 1 per hour

Light recommendations: N/A

Preparing grow blocks

Substrate choice for ‘grow blocks’ – many agricultural wastes and by-products can be used

Pasteurization of substrate

Bags & Fruiting containers

Introduction of spawn into pasteurized substrate

Inoculation rate for grain spawn into substrate is 1:10 meaning 1 part of spawn for 10 parts substrate; or a 10 to 12% spawning rate.  Lower rates of inoculation will result in slower colonization and perhaps lower yield.

Parameters and conditions for grow block maturation/spawn run : 4 weeks or more for incubation at 75◦ F or 24 to 25◦C

Following maturation bags are cut and flushing should begin within 7 days

Cultivating mushrooms from the grow blocks/ Parameters and conditions for cultivation/fruiting


OTHERS stains will require different parameters. Consult your supplier of blocks or spawn.

Fruitbody/mushroom development begins within days after the bags are cut:  make a vertical cut/slit in the bag at the top of the block


  • grow blocks should be kept at 16 to 18 C for production/harvesting;
  • 16 to 18C will yield slow maturing mushrooms with dense flesh and higher temperatures will yield faster maturing mushrooms with less dense flesh
  • Relative humidity:  82- 90%;
  • Light requirements: at least 100 lumens
  • CO2 must be kept below 850 ppm and this is achieved by air exchange; this will be at least 3 air exchanges per hour in the grow room; fan should be sized according to the room size – fans are graded by cfm (cubic feet per minute); grower must know room size and fan cfm and do the math

CO2: must be less than 1,000 ppm and ideally less than 850 ppm.  Oyster mushrooms are highly tolerant and responsive to carbon dioxide/CO2 levels.  Unless CO2 levels are kept below 1,000 ppm noticeable malformations of the fruitbodies will occur – typically long stems and small caps will result from high CO2 levels.  In fact, cap-to-stem ratio is an accurate measurement of atmospheric CO2 in the growing room and is used as a visual cue by Oyster cultivators for the need to increase air exchange. 

Duration:  mushrooms will develop from primordia to full clusters in approximately 7 days; harvest when mushrooms are young and in clusters.

Number of flushes – 2 flushes are typical and the yield from a 2.5 kilo bag of substrate is 2 or more lbs/roughly 1 kilo can be achieved if the conditions are good.  Grow blocks can then rest and a second fruiting can be expected within 21 days. For the second flush cut a vertical slit in the top of the bag on the opposite side to where the first cut was made.

 A third and even a forth flush can be achieved by injecting water into the block using some sort of syringe, or sprinkling the block, or soaking them.  For the third flush make a vertical slit in the bag towards the bottom of the block.  Fourth and fifth flushes can be achieved by replacing the moisture in the block by either injecting water into the block with a syringe or by soaking the block in water for an hour or two.  The goal is to replace approximately 1.5 kilos of water in the block. In order to know soaking time required grower can experiment by weighing a block before and after soaking.   

Following the final flush blocks can be buried in soil or they can be constructed into a ‘wall’ by making a frame and then stacking blocks and covering with soil.  Very high (400%) biological efficiency has been achieved using these methods and fruiting/forcing blocks up to 5 times.

Disposal of ‘exhausted’ grow blocks – exhausted/depleted grow blocks can be composted and perhaps used as supplement for animal/ruminant feed (depending on the substrate and tolerance of the animals).  

Storage and Handling

Containers – rigid cardboard boxes to hold mushrooms in a single level

Temperature – 35 F or 4C

Timeline from harvesting to delivery to ‘market’ is short; oyster mushrooms have a short shelf life and must be delivered to market and sold to the end-user as promptly as possible.

Distribution and transportation

Marketing and Pricing