Wijnen Square Crops has been working with Grodan since the mid-1990s and chose the Supreme mat for all their bell peppers two years ago. Crop manager Jeu Rutten explains how the slab supports the company’s generative cultivation strategy and why the slab is so reliable during the unpredictable crop season.

The company now known as Wijnen Square Crops was founded in 1978 by Jac and Mia Wijnen. With Pieter Wijnen, one of their sons, at the helm, it is a real family business to this day. He and his management team run two sites: an 18 hectare site in Egchel, where cucumbers and mini cucumbers are grown, and the ‘California’ site in Grubbenvorst. There the company produces red and yellow bell peppers, which are sold to leading food retailers in Europe through the Harvest House growers’ cooperative.

California was built in 2009 and consists of three greenhouses of about 11 hectares each. Cultivation manager Jeu Rutten has been working for the company for more than 15 years and is co-managing the activities in Grubbenvorst, where about a hundred employees work in the greenhouses during the high season.

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Perfect moisture balance
Wijnen buys the young pepper plants from a local nursery when they are around 45-50 days old. “We have agreed that the young plants are grown in the Grodan Plantop blocks, because a perfect moisture balance can be created in this; they do not stay too wet and do not dry out quickly, and they are the best choice in combination with the Grodan mats”, says Jeu.

 “We have been working together with Grodan as the sole supplier of our growing media since the mid-90s, when we started growing peppers, so you can rightly call that a long-term relationship! I used to have my own nursery and then I even worked with Grodan products. Grodan has a strong reputation and is a very reliable partner.”

Uniform performance
“As soon as the blocks are delivered at the beginning of December, we immediately put them on Grodan slabs on our hanging cultivation gutters,” he explains. “It is important to us that all slabs in the entire greenhouse provide identical performance, so that we can control all plants uniformly at the same time. Each slab must react the same and be equally moist and/or dry, which is very important with such a large cultivation area. Grodan’s products ensure that uniformity and controllability.”

About three years ago, GroSens Sensors were installed in one of the three California greenhouses, to test what added value this would have for monitoring. Jeu says: “A big advantage for us is that the sensors are wireless, which means that they can easily be moved to measure the conditions in the different parts of the greenhouse. We will probably eventually use this system in all three greenhouses in Grubbenvorst.”

He is also satisfied with the support he receives from Grodan: “Their technical advisor usually visits a few times a year and we are often in contact in between.”

Switch to Supreme
This is the third year in a row that Wijnen uses the Supreme mat. “We heard a lot of positive comments about this slab from other growers, and as a company we are always open to trying out new products and developments, which is why we switched to the Supreme slab for all 32 hectares in Grubbenvorst”, explains Jeu up. “A healthy root zone is essential to ensure good plant vitality throughout the season. In general, we have noticed that the Supreme mat supports the development of the roots better; the plants have many nice white roots and they are spread uniformly throughout the slab, rather than just on the sides.”

A better fit in the gutters
One of the great advantages of the 10 cm wide Supreme mat is that it fits well in the gutters of Wijnen. “Because the slab is narrower, more oxygen can circulate around the slab and the water can drain more easily, both of which contribute to a strong root zone. I even think that we had less trouble with Fusarium in the past two years because of that,” he says.

With a height of 10 cm, the Supreme mat is also a lot higher than the 7.5 cm mat that was previously used at Wijnen. “This works really well in conjunction with our watering system which is quite slow, 100cc can take as long as 5 or 6 minutes meaning we are making the most of almost 100% of the slab. The water spreads much more evenly around the roots and it is just as moist between the plants as it is directly under the plants,” says Jeu.

Support for generative control
He explains that at Wijnen they strive for a very active, generative crop control: “We are not afraid to create a more aggressive climate with the temperature and make the plants work a little harder, and the Supreme slab supports that strategy. We can now give the plants an extra drip, for example until 6 p.m. instead of 5 p.m., because the soaking process goes faster at night and the excess water can drain more easily.”

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Grodan: more circulation - gives stronger roots 5

“In addition, the better drainage gives us more freedom to stimulate fruit set by increasing the EC, because the slab can be rinsed out faster than before, even with our slow drip system. The reactive nature of the Supreme slab gives us more control over both EC and watering,” he continues.

Welcome reliability
“I’ve been in this business for 45 years, but at the start of a growing season I still don’t know exactly how it will go. There are so many unpredictable factors, such as the weather and diseases, so we have to stay focused all year round”, adds Jeu. “The Supreme slab gives us a bit of reliability that is so welcome during the hectic pace of a growing year, and is undeniably an important part of the formula for a high yield of high quality peppers,” he concludes.

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