The expansion takes the Norfolk-based glasshouse from 11ha to 18ha and raises its annual production from 80 million tomatoes to 140 million. It also makes Cornerways the UK's largest tomato nursery.
The catalyst for the third phase was the energy management system. The business benefits from its close proximity to the Wissington sugar factory's combined heat and power plant.
More than 386km of piping carry hot water from the plant to the glasshouse to heat the plants.
The expansion includes a one-million litre water storage buffer tank which stores hot water when the nursery's heating demands are low. After winning planning permission, building work for the latest phase of development began in June 2010.
Since opening in 2001, when the glasshouse covered just 5ha, the nursery has continued to expand by using innovative techniques to exploit the use of carbon dioxide, heat and water. The fitting of energy-saving screens as part of phase one enabled the addition of a further 6ha phase two development during 2007.
Colm McKay, British Sugar agriculture director, maintained: "Cornerways demonstrates our commitment to minimising waste while sustainably increasing our growth within the UK tomato industry to meet customer demand for home-grown tomatoes."
The nursery was recognised as the most carbon friendly commercial greenhouse in a Horticultural Development Company-funded carbon footprint report by Bangor University.
Cornerways horticulture manager Nigel Bartle said: "We've had to watch, learn and understand how the relationship works with the available resources - the surplus heat and carbon dioxide from the processing plant - and adopt new technologies."
PEST CONTROL APPROACH INTEGRATED MANAGEMENT PROGRAMME
Cornerways integrated pest management (IPM) programme has been so successful that it has eliminated spider mite, leaf hopper and russet mite from its phase one and two glasshouses.Only whitefly is a continuing pest.
It has also developed a system where the old crop haulm is cut down and left to decompose beneath plastic sheeting underneath the hanging gutters.
Mark Jones of BCP Certis, which over the past decade has advised the nursery on IPM, said: "This system would not be viable without good pest and disease control. The crop should be as clean at the end of the season as it is at the beginning."
He added: "The one pest that may carry over is whitefly. However, in the original two phases the parasitic wasp macrolophus has established - supplementing the control achieved using wasp encarsia."