"UK: "LED is ‘astonishing’ for winter tomatoes"

Flavourfresh, which produces nearly three million kilograms of tomatoes a year for the likes of Asda and Marks & Spencer, introduced LED lights two years ago at its greenhouses in Southport, to keep production going during the winter months. Production manager Andy Roe says the results have been ‘astonishing’.

‘The technical specs, and our expectations, were all met in year one’, says Roe. ‘Everything from plant growth to fruit quality and flavour.’ Growing through the winter is a nerve-wracking business, he says, but ‘by the blessing of the tomato gods we got it spot on’.

With their low energy consumption and finely-tuned light spectra optimised for plant growth, LEDs are increasingly replacing high-pressure sodium – which has been the light source of choice in horticulture for decades.

Even so, Roe says LEDs aren’t quite ready to meet all Flavourfresh’s needs. For its newly built 17,000m2 greenhouse, he has chosen to go back to high-pressure sodium again. The reason is not so much light, but heat.

While LEDs give off relatively little heat, HPS lights emit a lot. In many applications this would simply be wasted energy, but in a greenhouse the heat can be useful – provided it is kept under control.

Roe says the quality of tomato that can be produced in the UK in winter under artificial lights is ‘identical to the quality that can be produced in summer. There’s a cost to achieving it, but the UK customers are prepared to pay for it’.

Flavourfresh’s existing LED installation is in a relatively low-ceilinged greenhouse where HPS lights would have been very close to the crops, with heat potentially causing damage. But the ceiling of the new greenhouse is two metres higher, allowing a sufficient gap between the plants and the lights, and making sodium a more attractive option. A warm environment at the top of the plant helps keep the crop dry, encouraging it to generate fruit, explains Roe.

‘We had to decide what was the best way forward, and we visited other growers using HPS,’ says Roe. ‘There are pros and cons. HPS gives a more aggressive form of light and it costs more electricity to run, but as a grower, the effect on the top 10 centimetres of the plant is so influential on the fruit. It’s the model for what goes on in the next six to seven weeks.’

And although LED lighting would mean lower energy costs and potentially bigger yields in the long term, the high upfront cost means the payback is quicker with HPS.

But Roe still believes LED is the future. ‘LED is getting a lot better,’ he says. ‘Growers will understand and modify and get the best out of the units. It will become standard in 10 years.’

Picture courtesy of the British Tomato Growers Association

Horticultural Lighting Conference
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Source: Lux Magazine