As publ i shed i n S oi ll ess Aust ral i a Vol 4/2010, the offi ci al newsl etter of Prot ect ed
Croppi ng Aust ral i a www.prot ected crop pi ngaustral i a.com
Growing plants in 2010 is easy – relatively speaking of course. One reason for this is due to technological advances that early Australian growers could only dream about. Today the country’s high-tech, energy efficient structures offer precise environmental control and optimum growing
conditions.
Commercial Australian greenhouses have progressed through the 20th century from simple glass frames and low-walled pit houses to high-walled, well-ventilated, mechanised and computer-controlled glass and plastic houses on a technological par with the best in the world.
Changes in greenhouse structures have been driven by innovations in framing and covering materials, increasing energy costs, new pests and diseases, market demands and the overriding need to adapt northern hemisphere technology to the Australian climate. Protected plant production in Australia has come a long way – even since the early 1990s.
Nineteenth century nursery people in Australia grew large collections of rare and exotic plant species from around the world. They grew them under glass for the same reason as modern flower, vegetable and nursery growers – to propagate and mature plants, fruits and flowers not native to Australia’s climate in a protected environment.
And just as the early growers seemed obsessed with importing plants from overseas, so too has Australia imported much of the technology for growing plants.
Greenhouse design and construction has been no exception. However, unlike growers in the northern hemisphere, Australian greenhouse growers rarely face a lack of light nor the need to insulate against long, cold, dark winters, unless of course you live in the Dandenongs, Victoria, Tasmania or the Adelaide Hills. The biggest challenge facing designers of Australian greenhouses has been to cool and ventilate the structures during summer.
The early days
The design, glass and even framing, if cast iron, for most early glasshouses was imported from England.
Advantages in cast-iron technology, being developed for the ship-building industry of the late 19th century, enabled the construction of increasingly larger glass-clad houses with sufficient strength to support a considerable weight of glass.
The magnificent Palm House at Kew Botanic Gardens, Adelaide is testimonial to the skill of the craftsmen of the period, but most commercial structures were more modest.
Australian nurseries at the time typically used both glass frames, which could be raised, lowered or moved to protect seedlings or young plants according to the weather, and pit glasshouses.
The pit houses had below-ground, bricked lower walls, waist-level bricked benches and above-ground glass on a timber or cast-iron frame, which allowed for head room but little more. The earth walls insulated in winter and summer.
But growers at the time already realised the need to improve design and some pit houses had adjustable handoperated side or roof vents or movable glass panels to allow hot air to escape in summer.
The raised beds were often filled with shell grit or limestone pieces to ensure good drainage and, in some houses, hot water was piped to raise bed temperatures in winter.
Floors were bricked or earth. Humidity was high and air movement low, but some of these gems are still in use today as propagation or plant houses in retail and wholesale nurseries.
Pre-plastic

From the turn of the century through to the 1950s, most nursery, flower and vegetable growers used narrow, low-walled, timber-framed, ridge and gutter or gable houses covered with glass.
Large arrays were typically multiples of single houses, often with dirt floors, poor drainage, louvred side vents, solid one- to one-and-a-half metre side walls, and a ridge height of about 2m. The glass panes were small, set with putty, and, through the Great Depression and war years, difficult to source.
The houses were white-washed in summer. Well into the 1960s these houses dominated the near-city tomato, cucumber, capsicum and flower industries and variation on this design are still to be found. Crop temperatures in summer could exceed 50°C due to lack of ventilation.
From timber to steel
The 1920s saw the introduction of rustless steel frames, pioneered by the Dutch in the early 1900s. Steel allowed greater strength, fewer supports, and a good seal, gradually removing the need for glass putty. But timber and putty were still used even in quite substantial glasshouses into the 1960s.
Nursery hygiene, especially in the seedling industry, was also greatly improved in the 1920s by innovators such as W Bone and Sons in Melbourne, who, in conjunction with the Victorian Department of Agriculture, were among the first to use steam for soil pasteurisation for seedling production.
Wider, taller Dutch and English single or double gabled, Venlo-style houses, made possible with technology to produce larger panes of flat glass and galvanised steel beams and glazing bars, were expensive imports in the
‘50s and ‘60s.
These houses were sometimes fitted with evaporative pads and fans and increased venting to ensure adequate cooling through summer, although the local technical support to service this technology was sometimes lacking.
Big changes in the ‘70s
Plastic films and fibreglass, available overseas since the late ‘50s, began to replace pane glass in Australia in the late ‘60s and ‘70s, changing the industry substantially. These new materials – some made locally, some imported – were lighter, flexible and, significantly, cheaper.
Galvanised pipe frames allowed for curved profiles and wide plastic sheets enabled relatively large structures to be inexpensively covered.
Plastic also reduced the need for extensive support framing, opening out the interior of the larger houses, allowing good light transmission, and increasing production flexibility.
Industry pioneers at this time included Bob Campbell and Graeme Salter who later formed Sage Horticultural and Croft Polythene Greenhouses, respectively.
According to Bob Campbell: “Those early frames were half-inch water pipe bent around a gum tree. But once the poly-house idea caught on, the industry moved along rapidly.”
The inexpensive houses were a boon to the rapidly expanding nursery industry.
For the first time, the industry moved away from the traditional gable structure. But although the introduction of plastic films and fibreglass sheets enabled a cheaper structure and more flexible design, adapting the new products to Australian conditions, in particular, high ultra-violet levels, dusty winds and high summer temperatures caused problems.
The early plastics and fibreglass often clouded or shattered after relatively brief exposure to Australia’s harsh environment and some products were lucky to last two seasons.
The era of the plastic ‘igloo’ was born, but growers needed to weigh short cover life and poor ventilation against lower set-up costs.
These structures – still in use today in many nurseries as inexpensive propagating houses or basic protective shelters – often rely on passive ventilation down the long axis from end to end. No wind, no ventilation. Raised walls, screened or roll up side vents, larger doors, and alternative covers have greatly improved the performance of this design in recent years.
Overseas change

The ‘70s were a period of major change in overseas greenhouse technology with significant improvements in greenhouse climate management and irrigation and promotion of mechanisation.
Hydroponics, drip irrigation, carbon-dioxide enrichment, moving benches, automation and increasingly better sealed structures that reduced heat loss in winter were gaining popularity in Europe and North America.
Many of Australia’s key greenhouse supply and irrigation companies were established during this period along with the first greenhouse production ventures based on the importation of overseas product handling and hydroponic technology – the beginnings of serious private investment in the greenhouse industry.
According to a company at the forefront of fibreglass structures at the time, Controlled Environment Structures’
John Falland says: “Technology suddenly caught up with the industry in the 1970s but, for many, the costs of implementation were not matched by improvements in productivity – especially in the flower and vegetable industries.”
The late 1970s and early ‘80s also brought the energy crisis, big fuel bills for heated greenhouses, and interest by government and university research and funding agencies in alternative energy use, including the use of solar power for heating and cooling greenhouses.
Drs Keith Garzoli and John Backwell, then of CSIRO and, later, Geoff Connellan of the University of Melbourne’s
Burnley College, developed demonstration structures that incorporated aspects of new technology. These structures included solar air and water heating, rock piles for heat storage, solar heat pumps, flooded floors and some innovative ventilation designs, and established an ongoing interest in protected cropping structures and technology by Australian horticultural engineers.
Geoff Connellan – known to many in the hydroponics and protected cropping sectors for his commitment to improving greenhouse design and crop microclimate – says: “Big advances in energy conservation through the
‘80s included the use and steady improvement of internal, adjustable screens for heat retention and shading,
and the adoption of the double skinned greenhouse.”
Refinements
Increases in vent size, vent to floor ratio and gutter height, and greenhouse profile changes continued through the ‘80s and ‘90s as manufacturers strove to improve production efficiency and climate control.
However, larger internal greenhouse volumes often required greater structural and fabric strength to avoid damage in strong winds.
The cost of the new structures was a major deterrent for many in the nursery, flower and vegetable industries as profit margins began to decline from the good times of the early ‘70s.
A decade of change
Perhaps the biggest changes to the industry in Australia have occurred since the early ‘90s. This has been a period coincident with industry driven promotion of best practice and quality assurance, the adoption of an
Australian Standard for steel frame construction (AS-4100, 1998) and substantial private and public investment in protected cropping, particularly in the hydroponics industry. New pests and diseases have necessitated a total rethink of greenhouse management, screening and hygiene.
New irrigation concepts such as ebb and flow, flooded floor, and better micro-irrigation systems, along with legislated changes to waste-water management have substantially improved greenhouse irrigation and drainage.
The refinements of computer-driven technologies allow the micro-management and automation of greenhouse climate, and crop production and handling at a time of increasing labour costs and smaller margins.
Greenhouse supply company Powerplants Australia Pty Ltd’s David van Loon says: “Australian greenhouses have gone from being merely a cover to protect plants from extremes to a controlled environment structure with temperature regulation to within .5°C and managed air flow to provide optimum growth conditions for any
chosen crop.”

Product and technology is entering Australia from Europe, North America, Israel and New Zealand, but there is also a desire to source locally where possible. Framing materials are frequently produced locally, but some plastics and even glass are still sourced overseas.
Improved film
Neil Sutton, general manager of VP Industries in Queensland, a plastics manufacturer that has worked with the industry since the late 1960s says: “Recent advances in plastics extrusion and chemistry, with the incorporation of additives that alter the light transmission characteristics, strength and product life of plastics, have
revolutionised the industry.”
New generation single, multi-layer (co-extruded) and woven films have better ultra violet (UV) stability, and an increasing number of properties from anti-condensation, reduced drip, and modified light transmission that can influence plant growth and pest and disease development.
Greater film strength and wider widths enable higher, wider span greenhouses with minimal internal support for more efficient product handling and greater mechanisation, ventilation and screening options.
Most manufacturers agree on the need to maximise the roof vent to floor area ration. And, whereas plastic films and sheet coverings will continue to weather as a result of exposure to Australian UV levels, a new generation of polycarbonate products comes close to glass in performance. For some crops, the slightly diffused light from polycarbonate structured sheets is preferred.
Glass
And what of glass? Whereas plastics have become the trademark of structures designed for more temperate climes, glass has remained the bastion of the northern European industry, still regarded as the home of cuttingedge technology.
The Dutch-style high wall, interconnected Venlo houses continue to hold a strong place in the Australasian nursery and flower industries, particularly in New Zealand and those areas of Australia with a strong Dutch influence such as the east and southeast of Melbourne.
Dutch glasshouses are being constructed in Australia. In some cases these are used facilities, but in other cases, totally new glasshouses are being built.
Improved technology too has lead to major changes in framing and glass pane size. The glassed structures sold by New Zealand’s Faber Glasshouses Pty Ltd feature very high walls, with massive panes giving high light transmission. These houses are used to produce high-margin crops such as export cherries, cut flowers and export vegetables.
The future
The uptake of greenhouse robotics and automation in Australia lags well behind Europe and North America, but the greenhouse of today is still a very different operation compared to a decade ago.
Additionally, best practice protocols for pest and disease management have revolutionised weed management, drainage, irrigation, and greenhouse hygiene.
But ask any manufacturer or consultant working with the greenhouse industry what the key to optimum greenhouse production is and the answer will be “ventilation” and there is still room for improvement.
Effective ventilation is essential to maintain uniform internal temperatures, reduce relative humidity, condensation and fungal disease, and minimise areas of stagnant air.
Fan-forced ventilated greenhouses are not as popular in Australia as in some other greenhouse countries due to high operating (electricity) costs of the fans. The focus here is on naturally ventilated structures.
But options that maximise natural air movement include computer controlled rack and pinion roof vents, small circulation fans, roll-up sidewalls, ever larger ridge vents in gables, saw-tooths and the new breed of gothic arch designs, and retractable roof structures.
Vent position, size and screening options are available to accommodate wind direction, climate, and crop and pest management.

Connellan says: “Geoff Connellan says that high wall and roof heights, together with generous ridge ventilation, are now accepted as good greenhouse design practice. Optimum growing conditions can now be readily achieved.
The adoption of technologies that improve the growing environment and assist in the better management of the crop exemplify the increasing sophistication of the Australian greenhouse industry. Fog cooling and increasing use of PC based integrated controllers are two examples of technological developments that are being incorporated in greenhouse facilities.
Another characteristic of the industry is the recognition of the value of appropriate expertise to manage greenhouse facilities. Whilst there has been increased reliance on international growers in recent years, excellent training programs and state of the art training facilities have been developed locally to aid growers in producing viable crops in a sustainable way.
The quality of the produce and efficiency of use of valuable resources, such as water, will be strong drivers in
the further maturing of Australian greenhouses” he says.
Acknowledgments; This paper was first published by Rural Press, in Australian Horticulture, Centenary Special “A century of Australian greenhouse structures” in 2003 by Anne Frodsham. Considerable thanks to Geoff Connellan and others quoted, including the late Keith Garzoli, and Gail Barth for assistance in compiling this brief historical record.
1860s: Pit glasshouses and glass frames used for propagation
1875: Model Nursery built by C.F. Newman, Water Gully, Adelaide
1920s: First interconnected, low-wall, gable-roofed glasshouses using rustless steel frames
1934: The Seed and Nursery Trader described benefits of electricity for automation and precision of greenhouse climate control and replacement of timber with rust-less steel frames
1950s: Early importation of English or Dutch Venlo glasshouses
1950s: Electric timers, temperature and humidity sensors and increased automation
1954: Forced air glasshouse ventilation pioneered in the United States
Mid 1950s: Nurseries adopted UC system for steam/air pasteurisation
1971: First plastic tunnel house built in Australia
Early ‘70s: First fibreglass structures in Australia and beginnings of commercial hydroponic production
1979: First solar-powered greenhouse constructed by CSIRO
Early ‘80s: First double skin greenhouse in Australia; first use of internal energy saving/shade screens; moving benches, sub-irrigation technology
Late ‘80s: More emphasis on passive ventilation
Early ‘90s to present: First retractable-roof house imported and greater range of greenhouse profiles and films available