Meadow Mushrooms

March 2017

Canterbury based Meadow Mushrooms is involved in all aspects of growing mushrooms – from making compost, through to packing and distribution. It supplies about 72 per cent of the New Zealand mushroom market, with 98 per cent of total production sold domestically.

Meadow Mushrooms was founded in 1970. The company was co-founded by Philip Burdon, in Cypress (where it was mothballed then closed after the Turkish invasion in 1974) and Prebbleton, where it is still has a growing shed.

It is still 100 per cent owned by the Burdon family with three members on the board and Philip as chairman, however, the family is no longer involved in the day-to-day running of the business.

Meadow Mushrooms counts itself as one of Canterbury’s most efficient food producers, consuming only 30 litres of water to grow 1kg of mushrooms. That compares with 75 litres for 1kg of potatoes, 500 for 1kg of wheat and 12,000 litres for 1kg of milk powder. Little land is required to grow about 20 tonnes of mushrooms per day, using 23,000 tonnes of local waste-streams as a growing medium.

The company has 38,000 square metres of growing space, spread across five sites near Christchurch where up to 160 tonnes of mushrooms are hand picked each week. Five hundred and twenty staff work across two eight-hour shifts. They are mostly full-time or part-time workers, with few casuals. “If they stay for two years we’ve found they’re here long-term,” says managing director Wayne Collingwood, of the 40 nationalities who work for the company.

Two varieties of mushrooms are grown – white buttons and browns, which can be let to grow out to portobellos.

The process starts with making compost on the company’s farm near Dunsandel south of Christchurch. Ingredients are wheat straw from two contract growers, chicken manure from local farms and gypsum.

“We harness the natural composting process,” says Wayne. “Normally fungi and bacteria colonise and break down compost but we get the fungi we add to grow in the mix.”

First, the straw bales are dunked in nutrient-filled Meadow washdown “goodie” water. They sit for two days then start to heat, as the naturally occurring microbes rapidly multiply.

Large machinery then breaks the bales open and stirs chicken manure into the straw. The mix is stored in closed concrete bunkers with air blown up through “spigot” floors full of holes. Microbes multiply and gradually heat ingredients up to 80 deg C. The straw starts to soften and caramelize, taking 10 days to a fortnight, depending on the season.

Pasteurisation is the next stage, with half the compost trucked to the company’s original site at Prebbleton and half remaining at Dunsandel. The Prebbleton mix is spread out on trays stacked five high in growing rooms while at Dunsandel, a more modern shelf system is used.

To kill any potentially toxic microbes from chicken manure, all compost is heated to a precise 54.5 deg C and held for eight hours, so that every part reaches that temperature. In the shelf system, this happens naturally but in the trays some heating with steam is needed.

The compost is then conditioned, converting nutrients to a useable form. Air is drawn out using fans and dilute sulphuric acid added.

Next comes the adding of spawn, produced at Meadow Mushrooms’ Miranda Laboratories. Wheat or rye grains colonised by mycelium are sprinkled over the mix. After two weeks the compost is fully inoculated and ready to grow mushrooms.

Mushrooms are not plants. Their lifecycle starts with spores which when they germinate produce a fine, white stringy substance called mycelium which grows in fresh food.

A 5cm layer of peat is layered on top of 30cm of compost, to keep it from drying out during cropping and boost naturally occurring enzymes that encourage mycelium to fruit. Just as mushrooms sprout in autumn and sometimes spring in paddocks, dropping ambient temperature and freshening the air create ideal growing conditions.

The first mushrooms are harvested 16 days after compost is taken into the growing rooms, hand picked directly into boxes, punnets and trays. Compost and peat is emptied out of trays and shelves then carted away on trucks for use by farmers and gardeners.

Trays are now replacing shelves as they are more productive and efficient in many ways, including being shifted by conveyor belts rather than diesel-burning engines, and ease of picking. Stacked five-high in a growing room, each holds 2.3 cubic metres of seeded compost, hand-picked from top to bottom by workers on ladders.

Shelves were developed at Meadow’s Morrinsville base which closed in 2011, with production moving when composting smells became a problem. Odour issues also became a concern at Prebbleton as this rural area evolved into a settlement. The decision was made to buy a farm at rural Dunsandel, just south of Christchurch, and relocate all composting there. Fully enclosed concrete compost bunkers were built with scrubbers and bio-fillers to clear any odours.

Meadow now has 60 growing rooms, totaling 38,000 square metres with plans for more. Here it grows enough mushrooms to supply 70 per cent of the New Zealand mushroom market selling to supermarkets, distributers such as Turners and Growers, and to food service and restaurant customers.

This is a vertically integrated company covering every level of the supply chain from creating compost and spawn through to hand harvesting, packing, distribution and sales.

Wayne says the biggest challenge is consistency, with demand fluctuating between seasons and mushrooms doubling in size 24 hours. Once the gills underneath the mushroom cap start to open, it shortens the storage life and makes mushrooms less marketable.

With a shelf life of only 10 days and transport taking up to five days, only 2 per cent of Meadow Mushrooms are exported. They are sold to Hong Kong and the Pacific Islands.

Volumes can be manipulated in response to demand, says Wayne, but inevitably there is surplus crop. This is mostly processed at the Meadow cannery, five minutes drive from the growing rooms, and also donated to Canterbury food bank, the 0800 HUNGRY ministries trust.

Meadow Mushrooms sees great potential to drive mushroom consumption beyond the average 2.1kg that Kiwis eat on average each year. They are a low calorie, high nutrient food, low in fat and cholesterol free. They are packed with the B group of vitamins (important for especially women’s health) and also offer selenium, in short supply in New Zealand soils.

Research is demonstrating health-enhancing properties including reducing inflammation of heart arteries, which may protect against heart attacks and warding off prostate and breast cancers. And says Wayne, “aside from being incredibly healthy…they’re very tasty”.