The De Bakker brothers have been growing tomatoes on the Middenzwet in Wateringen for years. Since the 1960s, when their father and uncle set up the business, it has grown steadily to 3.7 hectares of glasshouses. In it, loose tomatoes were grown. Until the year 2020. That's when the last tomatoes came out of the greenhouse. The tomato growers became seed growers.
The step to seed cultivation had already been taken in 2019. At the time still in part of the greenhouse, Marcel de Bakker explains. "We left 1 hectare empty because the challenge of getting enough staff each time started to hamper us. With that greenhouse, we approached Rijk Zwaan, whose tomato variety we were already growing. They were interested in using our greenhouse to grow seeds. Not for tomatoes, because the glasshouse would have to be modified quite a lot for that, but for lettuce and spinach seed production."
The greenhouse had to be modified for this as well. "A lot of seed production is still done in the field. We do grow seed in greenhouses, but these are crop rotation systems where the seed grower grows different crops every year. We started growing on substrate, on rock wool, right from the start. You don't see that much anymore. As of this season, there are four growers at Rijk Zwaan who grow seed on substrate."
Marcel shows how high the crop can get, here with the cauliflower. Fellow growers who sometimes come and see the crop are sometimes surprised at how high it grows. "You can see them thinking: 'That's not lettuce anymore, is it? I didn't know that at first either."
Changing tap sections
In 2021, for the first time, the entire area was used for seed cultivation. The greenhouse had to be adapted for that. The watering was important. Horticoop Technical Services was called in to adjust the watering system in such a way that the seed growers are flexible and can grow many different types of crops at the same time. Product specialist Reinier van Zanten: "New main and secondary lines with new tap sets have been installed."
As well as other, sometimes double, drip hoses. Marcel: "The planting distances vary considerably between crops. Lettuce cultivation, for instance, requires a planting distance of 20 centimetres and seed cultivation of spinach 34 centimetres. You have to take that into account as well. The sizes of the tap sections also vary. Reinier: "The system pumps are therefore fitted with frequency converters in order to control the pumps optimally with varying crane sections."
The necessary new taps were installed to give the seed growers flexibility in their watering.
Many types of crops
When Marcel begins to list the range of crops for 2022, it becomes clear why this new installation and flexibility is necessary. "14,000 square metres of spinach, 15,000 metres for 25 different types of lettuce, beetroot, celery, carrots, endive and beans. Oh, and don't forget the cabbages."
That seed crop is already in full swing in early February. "Cabbages need cold to shoot," Marcel knows. He points one by one to the varieties planted on a total of 4,000 square metres. "We have green cauliflower, romanesco, kohlrabi, white and purple cauliflower standing side by side for a crossbreed and also red cabbage."
The purple cauliflower is already starting to sprout in early February. Later a tent is erected over it. Next to the purple cauliflower is a white one. It should produce a hybrid variety
Change and yet certainty
Out of all varieties, lettuce and spinach are already major seed crops, the rest are still more experimental. "That's because seed cultivation on substrate is fairly new."
Together with the four growers and the breeding company, they are learning to deal with the new way of growing seed, whereby watering as efficiently as possible requires particular attention. "The entire seed cultivation on substrate is actually still one big search."
For the De Bakker brothers, 2022 is the second year in which they will start working with the 'total package'. "With substrate cultivation, Rijk Zwaan is less dependent on crop rotation. With our method of cultivation, you can grow any product every year."
Marcel observes that the range of varieties does change considerably. "That makes it fun. Growing tomatoes from seed is new to us anyway, and after growing tomatoes for a long time it is a nice change. Even now that we grow tomatoes from seed, the variety is still there every year. Let me give you an example. Of the 25 varieties of lettuce that we are growing this year, only two are the same as last year. Meanwhile, seed cultivation gives us security. That is nice at our age."
The corner with the cabbages
Fun and educational
Not that Marcel thinks that seed cultivation is inherently suitable for somewhat older growers in mostly older glasshouses. The well-kept greenhouses in Wateringen, with a planting height of 4 metres, do not meet the latter qualification, for example. "We grow cleaner than ever", Marcel laughs. "We have never swept the path as often as we do now. After every planting, the broom goes over it."
Moreover, the grower has made a considerable investment due to the switch to seed cultivation. "I would like to show how beautiful seed cultivation is and that it is not something that can only be done in old greenhouses. Especially when everything is in full bloom here, it's wonderful. You also learn a lot. Did you know, for instance, that at a certain point in time you have to cut the head of a red cabbage so that the plant can shoot? I didn't, but with advice from Rijk Zwaan we learn a lot."
This spinach was planted in early February. From that moment on, apart from the cabbages, the other crops are coming as well.
Falcon box
What the growers have also learnt is that sparrows like to share in the benefits of the seeds. That is why this year, in consultation with a falconer, a hive will be installed at the growers' premises. "According to the specialist, a falcon will appear if we make sure there is some straw in the cupboard. That falcon should help us keep the sparrows away from the seed. Last year, there were suddenly a lot of them. We had never seen them before, but suddenly they were there. A cheerful sight in itself, but we prefer them outside. In the greenhouse, they defecate and I discovered that they gnawed through the jute ropes near the beans, causing stems to fall. That made quite the mess."
At harvest time, when the crop has grown considerably, it is sent out in cubic boxes. Rijk Zwaan then dries and threshes the crop to extract seed. In the first two years, the brothers did that themselves for the 1 hectare seed crop, but on a larger scale that is no longer possible, as it is a lot of work. At the same time, seed cultivation gives the growers less work, which is also the reason for the switch. "We can do a lot with the three of us and if necessary, some relatives come to the rescue."
Most of the buckets are incorporated into the soil, between the crops. On the path, this bucket is slightly higher.
No rinsing
A daily recurring chore is checking the watering. "You have to pay close attention to that seven days a week. That is different in soil cultivation. We check the buckets we have for catching the drainage every day."
A new climate computer, installed by Horticoop Technical Services, also helps to determine how much water the crop needs. Reinier: "We have replaced the outdated Hoogendoorn Economic for an iSii Next Generation. The existing matrix taps were also converted to a Datapoint."
Marcel and his brothers water based on the crop that is drinking the most. "If there is too much, the plant will drain it. Meanwhile, you don't want to flush too much either. But too little water is more dangerous. After all, you do not want to stunt growth. That is why we aim for 20-25% drain per day, minimum. With our new installation, we can monitor this well. It helps us take steps as a seed grower and become better and better at it."
Still quite empty at the beginning of February, but soon, when everything is flowering, it will almost be an 'ornamental crop'.
For more information:
Marcel de Bakker
B.L. de Bakker en Zn. bv
Middenzwet 29
2291 HM Wateringen
[email protected]
Reinier van Zanten
Horticoop Technical Services
[email protected]
www.hcts.tech