Biesbrouck Greet bvba is the first Belgian tomato nursery with LED-interlighting. After eight months, owner Luc Coghe sees a big rise in yield, better quality and taste and more vigorous plants. But actually the first season has just been a year of learning. Things could be even better and that will be necessary to achieve the desired profitability.

Tomato production under glass is rare in Wallonia, the French speaking part of Belgium. Therefore Luc Coghe’s 7 ha greenhouse in Pecq (Henegouwen province, on the border with West-Vlaanderen) certainly catches the eye. Actually it’s just coincidence that he’s ended up here about 45 kilometres from his old nursery in Ardooie (the Roeselare horticultural region). “We’d been looking for expansion possibilities around Ardooie for several years. But there due to the fragmented plots available it was difficult to build a nursery of about 10 ha. Here in Pecq we came across a landowner who wanted to discontinue his own business. The dimensions of the plot appealed to me and the price also played a role. It is somewhat further from the REO auction, but much is sold directly so that’s not a problem.”
That was ten years ago. The business, which is in the name of his wife Greet Biesbrouck, now has two locations. Mrs Biesbrouck runs the old 2.3 ha site in Ardooie.

Regional brand

They grow three types of tomato in Pecq: loose (variety Kanavaro), cluster (Plaisance) and cluster cocktail (Brioso). They are members of the growers association Tomabel, which has additional specifications; a set of requirements that go beyond those of the umbrella brand Flandria. “These specifications cover varieties, presentation, sorting standards, nutrition, pruning strategy and planting distance. They put additional emphasis on quality which costs a small fee in return,” explains the grower.
He has a strong innovative attitude with an eye for opportunity. In this way he is starting to promote himself as a local producer. “This is interesting for our buyers. We now have a customer in Wallonia for whom we do the packing ourselves. We use the label ‘Agriculture of Wallonia’ although this mark still has to become established. It is not yet recognised as a regional brand such as Flandria, but it is starting.”
Five years ago, with advice from Frank Florus, he equipped 2.6 ha of his greenhouse with SON-T lighting. Florus supervises many growers who use lighting, also in the Netherlands. “The reason for doing it was both financial and for labour planning. There is definitely a market for lit tomatoes and it provides a more continuous flow of income. Also you keep your personnel in a job. The profit from a traditional crop is not very good but there are still opportunities for winter production of tomatoes,” he says.

Hybrid system

Therefore last year he made an additional step in lighting in order to expand the winter production. Together with the advisor he had figured out two options: An extra 2 ha of tomatoes lit with SON-T, or hang additional LED-interlighting in the current lit section. “I had been interested in using interlighting in a hybrid system (together with SON-T) for quite some time. LEDs are an innovation and that appealed to me; this is the future. I visited the Dutch pioneers Jami, of Bergschenhoek, and Wim Peters, of Someren. They are convinced about the advantages of interlighting. We made calculations based on performance data supplied by Philips and a certain price level for the tomatoes. This indicated that the investment was justified.”
Now he has 6,600 Philips Greenpower LED interlighting modules (55 µmol/m2/s) hanging between the plants, at the height of the fourth cluster. The SON-T top lighting (170 µmol/m2/s) is used until 1 April; the interlighting is used for a month longer. But the lighting regime doesn’t stop there: the interlighting regularly comes on at sunset until the light level reaches 250 watt.

Grow differently

Interlighting requires a new way of growing. All pioneers say that the first season is mostly a year of learning and that’s just the same for Biesbrouck. In addition, each grower has his own strategy: do you first start the old way and gradually learn from experience or immediately try everything new.
“At first we didn’t make many adjustments,” says Coghe. “In principle the climate settings remained the same, just like the planting distance. But because the plants receive so much more light energy you have to respond to that. Otherwise the plant becomes too heavy. Therefore we have to use the pipe rail heating more. Next season we want to change things but in a structured way so we are writing down many of the lessons learned.”

Retain more crop

Decisions regarding the final adjustments to planting distance, pruning policy, type of plant, number of leaves and temperature strategy still have to be made. This will require some brainstorming with the consultant.
“You should aim for more crop in the greenhouse to optimally utilise the extra light energy. But whether you allow extra shoots to remain or start with more plants is still the question. But I’m sure that it makes sense to use the LEDs earlier. We started to use them at the third or fourth cluster but you could start earlier to give a few hours of extra lighting. Then you could plant closer together,” he says. “We could also allow the modules to move with the crop. Now they remain at the same height for too long.”

First season positive

Many decisions regarding cultivation still need to be made and the plant’s response brings all kinds of questions. But the fact remains that the impression after the first season is very positive. “The quality of the fruits is impressive,” he says. “The tomatoes are much more uniform and the green parts (crown and stem) are heavier. It’s striking that the taste is much better; that goes for all three varieties. Furthermore the harvest over the weeks is more even. The plant is much stronger, greener, resistant to diseases and leaf edges and it grows faster. Due to the more robust plant leaf plucking has become more difficult.”
He estimates that the extra production as a result of interlighting is around 20%. That is in line with the forecast for the first year. But such a high level is necessary to make the investment really interesting, he says. “The yield has to be better and there we still have work to do. The plant is often too strong and steering it generatively requires a different approach. I don’t expect that even after another year we’ll have learnt everything. But I’m confident it will work.”


After eight months experience Belgian tomato grower Luc Coghe is positive about the results of interlighting with LEDs. The harvest is more even and the tomatoes are more uniform. The plants are heavier and more robust. Production is 20% higher. The first season is mostly a learning process. Improvements in the cultivation should lead to higher profitability.

Text: Tijs Kierkels. Images: Wilma Slegers