Glasshouse buyers focus on effective no-frills kit

While some major builds are still going ahead, most nurseries are looking to tighten their belts.

Thanet Earth - an enormous venture involving 51ha of glass on the Isle of Thanet, Kent - is gradually taking shape. When completed it will produce tomatoes, cucumbers and peppers 52 weeks of the year and provide 550 jobs. For the vast majority of UK growers, however, the building of such a facility may be fascinating, but remains something of a pipe dream.

There have been big glasshouses built in the UK in recent years, notably the 5.7ha of high-tech glass for Dela-more at Wisbech. But for many, expansion means using second-hand glasshouses. And the rush for used glass means business for glasshouse construction firm Bridge Greenhouses, as contracts manager and manager of the Spalding branch Neil Watson confirms: "Well over half of the glasshouse-build from our Spalding office is second-hand; it's a very strong market," he says. "The houses come in from Holland and they are good - often only five or six years old."

Aside from Thanet Earth, the erection of new commercial glasshouses in the UK is relatively slow. The credit crunch and a dramatic rise in energy costs, plus a bad-weather year, means many nursery businesses have had to shelve thoughts of expansion for the time being.

Instead, they are looking for cost savings or even considering moving into cold crops, as Watson explains: "I suggest that the banks are slowing down major investment in new glasshouse developments at the moment; and certainly nobody knows where the fuel issue is going to end.

"The crunch will really come when people fill up their tanks ready for winter - we are talking about a 60 per cent increase in cost this year. Growers don't know whether to stick with the crops they've got and look at alternative energies and other means of saving fuel and cutting costs, or whether they should be changing to cold crops."

Many of the hi-tech new constructions coming from Bridge Greenhouses are currently for research facilities, universities and schools. These constructions tend to be small and are mostly for training purposes, but that is where investment seems to be available.

For general commercial production, the demand is now for basic, good- quality, no-frills structures that will withstand UK conditions. The Venlo remains the most popular for commercial enterprises.

"At the moment, investment from growers is in 'production as cheaply as possible'. Growers are looking for fairly basic units and are turning their attention more towards energy saving and alternatives," confirms Watson.

Bridge Greenhouses is currently undertaking a lot of work connected to alternative energies. Watson explains: "Although it still represents major capital investment, a lot of our business this year has had to do with the installation of biomass boilers at existing sites where growers are seeking cheaper ways of heating," he says. "Thermal screening has also been crucial as growers try to save what money they can."

The search for fuel savings has also meant an increased interest in alternative structures, such as the Keder greenhouse. UK supplier CLM Keder Greenhouses points to one example of a grower who made savings.

"Magor Road Nursery, at Langstone near Newport in Gwent, contacted us with some amazing fuel-saving statistics," says CLM Keder Greenhouses sales manager Peter Monahan. "Nursery owner Ian Neale has a Twinspan Keder greenhouse and has been comparing the fuel used to heat it against a similar-sized glasshouse at his nursery. Growing his crop of chrysanthemums would normally take between 500 and 600 gallons of heating oil, but with the new Keder house he has managed to grow the same outstanding crops, but only using between 100 and 200 gallons."

Savings may be possible, and the level of accuracy may have increased in activities such as the routine checking and monitoring of crops. Many growers of pot plants determine soil humidity by walking the house and randomly lifting pots, removing the container and assessing the root area. But the process is subjective; not to mention time-consuming. And it makes it difficult to control the glasshouse as a whole.

Some plants inevitably get too much water; others do not get enough. However, new equipment from Hoogendoorn means soil humidity can be monitored accurately - the resulting data giving an objective picture. Sensiplant from Hoogendoorn is a wireless monitoring system that automatically determines soil humidity of pot plants without the need to walk the crop. Developed by TNO in co-operation with Growlab Instruments (a part of Hoogendoorn Growth Management), the system is intended to provide for optimised irrigation, prevent growth disorders and boost production scale.

The system is based on a number of soil humidity sensors placed in containers. Every irrigation zone requires two or three sensors. The sensors measure the soil humidity and then wirelessly transfer the measurements to the central computer, allowing the average soil humidity of every irrigation zone to be viewed on the screen. The decision can then be made to change the irrigation strategy if necessary.

The sensors come in packs of five, 10 or 20 and their use is not restricted to any particular brand of greenhouse computer. The software uses standard internet browsers, and there is no need to install any full cabling infrastructure. The system can be used with ebb-flow or mobile benches and works irrespective of the size of glasshouse to give a continuous insight into soil humidity.

Sensiplant is another example of technology that helps growers become more efficient, make cost savings and increase profit. Combined with investment in the latest climate computers, alternative energies, fans and thermal screens, it seems there is light at the end of the tunnel.


Using misting systems in greenhouses allows additional features to the normal climate control.

During the day, air can become too dry and during the night there is a tendency that air can become too humid, neither giving the optimum climate for plants.

By using existing climate computers in combination with a misting system, humidity can be controlled to obtain the optimum climate during the day or at night.

Alongside controlling humidity, temperatures can also be reduced during the day when it may become too hot for the plants.

Practical experience also indicates that use of the misting system during the day also reduces humidity somewhat during night time.

Designed specifically for horticulture, the new Hydor Misting System is based on a 12mm A4 Stainless acid-proof pipe with a wall thickness of just 0.6mm. It has been developed to provide simple, fast and inexpensive mounting. The spring-loaded nozzle and clamp are guaranteed to be leak-proof.

The innovative mounting concept behind the system means it is no longer necessary to prefabricate pipes at the factory, or cut threaded holes in pipes of larger wall thickness, weld branch pieces on to pipes or use expensive cutting-ring fittings for nozzle mounting.


It's called Thanet Earth and it is heralded as the largest and most hi-tech commercial greenhouse complex this country has ever seen. It is sited on over 91ha between Birchington and St Nicholas at Wade, Isle of Thanet, Kent, and represents an £80m investment in the production of tomatoes, peppers and cucumbers.

As a result of Kent-based fresh produce supplier Fresca Group teaming up with three specialist large-scale growers, the project includes the construction of seven Venlo glasshouses - each one covering an area of 10 football pitches and totalling 51ha. The glasshouses will be owned by the three growers and will make use of the latest efficient hydroponic growing techniques. Each will be computer-controlled to produce crops 52 weeks of the year. They will also be equipped with supplementary lighting while CHP (combined heat and power) installations generate power for the national grid and supply hot water to heat the glasshouses plus carbon dioxide for optimum growing conditions.

So far, one house has been completed. The construction was undertaken by Dutch contractors but calling on local labour for the fitment of equipment and electrics. Two of the other glasshouses are currently being glazed and the remainder will be erected next year. The first crops from phase one are expected to be ready this autumn and will be packed in the 30,000sq m, on-site automatic packing facility.

Also on-site will be a research and visitor complex, as well as facilities for the anticipated 550 workforce.

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