Mushroom Production

There are many edible mushroom species that can be grown commercially, but in Ireland the white button mushroom (Agaricus bisporus) is almost exclusively grown. Production in Ireland is fairly steady at around 68,000 tonnes per year, 80% of which is exported to the UK.

The Irish mushroom industry

There are approximately 34 growers producing on 40 farms in Ireland. The industry employs 3,500 people. The number of growers and production units has declined over the past decade as small farms ceased production, while larger farms continued to expand to ensure they remained sustainable.

The Irish industry is based on a satellite grower system, whereby growers are linked into a small number of mushroom substrate producers and marketing companies. The substrate is delivered to the grower’s production units. The mushrooms are grown, then handpicked into punnets, collected by the marketing company, graded and packed at the packhouse and prepared for distribution.

Growing process

Mushroom growing is a very technical process and attention to detail is crucial. Mushrooms are grown on a shelf system in purpose-built growing rooms, where the growing environment is computer controlled to give constant temperatures of between 18°C and 25°C, and 90-95% relative humidity. The filling of the shelves with substrate is automated. This system gives optimal uniformity for growth. A layer of casing soil (black peat mixed with lime) is applied over the substrate. The casing soil acts as a water reservoir and aids the growth of mushrooms. It usually takes six weeks from when the substrate is filled until the crop is finished. During this period, the crop will produce three flushes (crops) of mushrooms. About 75% of mushrooms grown in Ireland are the traditional white mushroom variety, with the remaining 25% being brown varieties. Yields vary depending on mushroom type, size of mushroom picked (button, cup or flat), grower capability, air handling facilities, quality of operations, and number of flushes taken.

Setting up a commercial mushroom enterprise

• Significant capital investment is required, the average cost per mushroom tunnel is €200K.
• A skilled labour force is needed to harvest mushrooms.
• Access to markets to distribute mushrooms is essential.
• Technical mushroom growing knowledge and human resources (HR) skills are required.
• To gain access to markets, growers need to have quality assurance (QA) certification.

 View full factsheet here.