What growing conditions do Blue Oyster mushrooms require?

In the fruiting stage, Blue Oyster mushrooms require a temperature between 10-17 °C with a relative humidity of 85% RH. Carbon dioxide levels should be less than <800ppm, otherwise, you will end up with long stems and small caps. Light levels between 800-1500 lux is recommended.

What are suitable substrates for Blue Oyster mushrooms?

Hardwood/straw are the best substrate for Blue Oyster mushrooms. This should be supplemented with soya hulls or similar to achieve the right consistency.

How long does it take for Blue Oyster mushrooms to grow?

For the inoculation stage, it will take around 21 days for the substrate to be colonised and ready to fruit. After this, in the fruiting stage, it will take around 7-14 days for mushrooms to be ready to harvest.

Large cluster of grey oyster mushrooms growing on a metal shelf.

Blue Oyster Grain Spawn

Name: Blue Oyster Grain Spawn
Brand: Merit Mushrooms

SKU: GS-PO1.5KG

This species generates a heavy yield with many mushrooms. Large caps and short stems can be achieved with low carbon dioxide levels, creating the optimum mushroom. Mushroom bodies may last up to 14 days after harvest in the fridge.

Grain spawn is to be inoculated onto a suitable substrate and we advise inoculating onto a recommended substrate as described in the 'Cultivation Information' section of this page. The substrate is not included.

Our grain formula contains the optimum levels of nitrogen required for quick growth of mycelium as well as a high number of inoculation points. Weights of bags are approximated.

We aim to have all our grain spawn ready to dispatch whenever there is an order, but because it is a live mycelium sometimes dispatch may take longer. We will get in touch if this is the case.

As grain spawn is usually used by those with prior experience, we do not include any instructions with it. If you require any guidance on how to utilise the spawn, please contact us.

Note: We break all of our grain spawn before shipping for your convenience. The grain is fully colonised and can be used as soon as you receive it. The described information has been tested thoroughly and the optimum conditions have been listed. Because of this, results may vary if the appropriate conditions are not met.

Storage: We recommend using the grain spawn as soon as you receive it, however, if you need to store it for a longer period of time, store at 2 °C for up to 1 month.

Cultivation Information
Species: Pleurotus ostreatus

Recommended substrate: Hardwood/straw (wheat)

Fruiting duration: 4-6 weeks

Yield: Approx. 200-250g of fresh mushrooms per kg of our recommended wet substrate (1st flush); pre-inoculation

Inoculation % of wet substrate: 2-10%; higher inoculation % leads to a shorter incubation period. Do not exceed 10%.

Our recommended substrate for this species can be found here.
Incubation Conditions
Room temperature: 20-22 °C

Substrate temperature: 25-30 °C

Duration: 19-22 days
Fruiting Conditions
Induction: Decrease temperature to 6-15 °C @ 90-95% RH

Optimum room conditions: 10-17 °C @ 85% RH

Carbon dioxide concentration: <800ppm

Light levels: 800-1500 lux

Flushes: 2-3 flushes @ 1-2 weeks interval with 90% RH in between flushes
Bulk Orders
Below are the discounts we can offer for different quantities of grain spawn:

Quantity Discount

4-7 10%

8-19 20%

20+ 30%

Discounts are applied per order and grain spawn varieties can be mixed.

If you wish to purchase a large quantity of grain spawn to take advantage of our discounts, please contact us.
Delivery Information
Please read the delivery information here to find information regarding dispatch times and more.