When R&L Holt decided to modernise the Sandylands site where Rick started the family business from scratch over 35 years ago, there were no half measures. Three blocks of old glass, staff facilities and the boiler house were demolished to make way for a 1.13 MW Combined Heat and Power unit, modern staff facilities, offices and a state of the art 8,300 m2 structure fitted with diffused glass and lighting for year round production, all designed and built by turnkey specialists Certhon, who had previously completed greenfield projects for the Holts at their Hornsfield and Springhill sites.
Rick Holt and son Roly made up their minds that the renovation of the site where it had all started should give them the opportunity to supply specialist premium varieties like Piccolo and Elegance all year round. Mains electric is too expensive for lighting on this scale, so the Sandylands project had to include a CHP engine to provide affordable electrical power, as well as heat and CO2. Rick and Roly were also very keen that the investment should be as future proof as possible. In this case, that meant installing a hybrid system with HPS lighting overhead and Philips GreenPower LED interlighting in the crop rows, even though LED technology is still in its infancy.
Work started on the Project in November 2013 and was ready for planting the first short term crop in March 2014, grown on specially formed hanging gutters using NFT (Nutrient Film Technique). That was a great success, with higher yield and quality than expected, but the main challenge still lay ahead and the winter crop of Piccolo and Elegance was planted in September last year. Now, after their first winter under lights, things are still very much on track.
The 1.13MW CHP engine provides all the power required for the lights: 105 µmol from the HPS lights overhead and 110 µmol from the LED interlights. Allowing for a dark period of at least six hours a day, which is essential for the tomato plant, the lights are usually on from midnight to 5pm. A Combimatic screen supplied and installed by CMW prevents light pollution during the hours of darkness and energy saving when required for the rest of the day. Ideally, the plant needs a minimum of 1300 joules of light daily from November to early January, rising to 1600 Joules after side shoots are taken for full summer density’, says Rick. ‘Our hybrid lighting system provides 1100 joules, so we have to rely on nature for the rest. In the darkest months, we might only reach 100 joules of natural light on a dull day, but overall we more or less achieved what was required, and the crop looked good.’
The extra CO2 capacity provided by the CHP has lifted yields by 10% on average throughout the nursery, including in the one remaining conventional block, with an even higher yield under the diffused glass and LED interlighting in the new Certhon block. However, winter tomato production in the UK is not just about yield. In fact, there would be no point at all unless the end product is significantly better quality than imported fruit. Judging by the positive feedback received so far, the winter product has reached every standard they had set for colour, shelf life and flavour.
With any new venture, there can be unexpected problems. At Sandylands this turned out not to be with the lighting or CHP, but with the pest Tuta Absoluta, which, since first appearing in the UK on Spanish imports in 2009, has become a major issue for UK growers. Robust IPM regimes have been developed since then, but Rick has found that those don’t appear to work in winter on tomatoes. ‘We’ve been forced to employ insect traps, some chemicals and we’ve had to remove all crop debris from de-leafing straight away to keep on top of the problem, otherwise the crop could have been overrun.' When chemicals have occasionally been required the new spray robot has been a great boon - ensuring precise application and minimal use of labour.
Will it pay? Rick and Roly are very happy with their investment so far, thanks to the support of their marketing company EVG and UK retailers, so it looks like year round production in Evesham is here to stay.