The format has taken the Birmingham-based company six years of trialling from kitchen table to a commercial product, with support from Innovate UK - the most recent being awarded the day before the conference, he said.
"Our focus is on profitability through less labour and lower input costs, and we are seeing a threeto fourfold increase in yield per square metre. But it has taken time to get to that point because there are a lot of variables - fertigation, substrate, root zone temperature and so on. In fact, we are still looking for substrates all the time."
An internal sterilisation process "eliminates root zone diseases" while stocking is a simple matter of "push in, pull out", said Fisher. "It can go on any kind of space, even undulating, and has no pollution or run-off." So far the focus is on leafy salads, pak choi, herbs, strawberries and edibles flowers, he added. "Tomatoes are already in 3D and you get no more yield for baby leaves."
Fisher told HW: "You get more variation (between north and south sides) in winter than in summer when they're saturated with light anyway. Rijk Zwaan are working on a winter lettuce to address this, which we are trialling. White sheeting on the ground is effective (in balancing light levels around the crop)."
Strawberry growing trials with Manor Farm Fruits in Staffordshire have shown that planting at 29 plants per square metre can increase yield by four-to-five times over conventional cropping on the same area, with a payback on investment at just two or three years. "And picking is easy," added Fisher.
Worcestershire salad grower Valefresco has also given over 20 of its 220 polytunnels to the format. Harvesting began in March and has continued since. "Pak choi loves hydroponics, though it shows up any deficiencies", said Fisher, who is also a consultant to the company. "The cleanness of the product has helped it win new contracts with retailers and processors." It plans further conversion to the system this winter, he added.
Valefresco director Nick Mauro told HW: "You have less distance to move to harvest them, though you may harvest from the top one day and then from the bottom. Pickers can go from plant to plant in 1.5 seconds but don't find it tiring."
A threeto fourfold increase in lettuce yield over field-grown has also been achieved, coupled with a reduced cropping time and longer season, and a "very clean, saleable crop", he said. "Processors are keen on this as microbes are a big issue."
Likewise trials of basil growing with a major herb grower have shown it to be "quick and easy to harvest, with an extra four crops a year", while as a higher-value crop it offers payback of a year or less. In such a controlled environment "you can manipulate the flavour and push winter production", said Fisher.
He added: "LED lighting is a really interesting area but I see it more as supplementing and augmenting natural light. We are working with one LED supplier." The company's other plans now focus on developing international markets, including the USA and Far East.