National salad production could be boosted by 15% by Britain's biggest-ever glasshouse development, which has been given the go-ahead in Kent.

Backers claim the £70m project will offer retailers higher-quality British produce with a lower carbon footprint than rivals all year round. Thanet Earth, near Margate, will cover 50ha with glass to grow tomatoes, peppers and cucumbers. It will also include a 30,000 sq m packhouse.

It is part of a 50-50 joint venture between Fresca, the UK's largest fresh produce supplier, and three specialist Dutch growers. Thanet Earth MD Steve McVickers said the development was great news for British retailers. "It gives them the opportunity to partner with dynamic growers with significant quantities of consistent, top quality supply - and it all comes with a UK flag," he said. "The UK simply doesn't have anyone at the moment who can offer this."

Other key selling points would be Thanet's ability to provide consistent supply, 52 weeks of the year and an improvement in crop quality, he said. Growers would use significantly fewer pesticides during the winter than rival Mediterranean suppliers. And crops would be grown with heat and light generated using an efficient CHP plant. Waste carbon dioxide would be pumped into the glasshouses to boost plant growth, and surplus electricity would be sold into the Grid.

Work at the site has begun, and the first vegetables will arrive in supermarkets in a year. Product handling will be fully automated from plant to dispatch in the on-site packhouse.

Ironically, the development is taking place on the site of a defunct cauliflower business. But McVickers said he had no fears over growing price pressure in the fresh produce market.

"Our joint venture is a great formula as it increases the grower's market understanding, helps tailor product and planning to real demand and rewards him for the total success of the business," he said.