Cultivation
“By growing sustainably, we make the world a little better every day."
Bumblebees
Before tomatoes can start growing, the flowers on the tomato plant have to be pollinated. In the greenhouse, we use bumblebees for this purpose. The bumblebees live in special bee boxes spread strategically around the greenhouse. Just like honey bees, they collect pollen from the flowers. Why do we use bumblebees and not honey bees? Honey bees are used as pollinators with certain crops, for example many types of fruit trees. Their blossom is rich in nectar, so the bees stay close to this source. However, the flowers of tomatoes do not have a lot of nectar. The honey bees would quickly leave the greenhouse in search of richer food sources. And because bees communicate with each other, as soon as one leaves, the rest are likely to follow. Bumblebees are a little less clever and stay close to the food source. They are offered sugar water as a source of nutrition.
Crop care
Our tomato plants receive the best possible care and attention throughout their life cycle. From the moment they arrive in the greenhouse in December to the moment they are removed in November, all the plants together produce around 10 million kilos of tomatoes. Which is a pretty amazing feat! In fact, we like to compare our plants to elite athletes. Athletes who can only reach a peak performance in perfect conditions. So, every little detail must be taken care of. During the harvest season, everyone pulls together to coach the plants to success. A dedicated team is hard at work every day training the stems and pinching out the side shoots, pruning the leaves and harvesting the ripe tomatoes. Every day, the correct amount of water and nutrients is measured for each plant and the greenhouse climate is maintained at optimal levels. All so that our world-class athletes can perform to the best of their abilities.
Tomato plants grow all year round. This means that at some stage they grow so large that the main leader stem is not strong enough to support itself once the plant starts producing fruits. To guide the plants, a system of string creates a trellis suspended from the top of the greenhouse to the base of the plants. The plants can climb up this support. The plants have to be trained upwards, so as the stems grow they are twisted around the strings and clipped in place. A specially trained team does this task. They are specialised in this technique and know the crop well. So they also have a very important role in signalling anything out of the ordinary.
As the plant grows, it develops side shoots or suckers. These are new stems that appear in the joint between the leaf and the main stem and ‘suck’ some energy from the leader stem. For this reason, they are removed weekly. If these side shoots were left on the plant it would develop into a dense tangle of leaves and stalks and produce smaller, weaker vines of tomatoes.
An important part of crop care is pruning. Plants with fewer leaves are less dense, which allows more light to reach the fruit at the base of the plant. Obstructing light delays the ripening process. In addition, with fewer leaves the plant will dry faster so it is less susceptible to pests and diseases. Pruning must be done with great care to avoid causing gaping or frayed wounds where moulds could develop. Over-pruning is not good either. Fruits exposed to too much sunlight develop a poorer colour and a rough skin. And, in bad weather, the plant is unable to evaporate sufficiently, which can cause the fruits to crack or burst.
During the first months until the harvest, a tomato plant grows about 25 cm a week. This means that after about two and a half months, the canopy of the plants will have reached the top of the greenhouse (4.5 metres high). To ensure that the plants can continue to grow, each plant has a small ball of string that can be unwound. From March onwards, the plants are lowered by about 50 cm once every two weeks and moved along the supports. This means they can keep growing to reach a length of up to 12 metres!
The period from the moment of fruit setting to harvest takes eight weeks. The first tomatoes start to ripen in March and are picked from the vines. This is done by hand. After harvesting, the tomatoes are taken to the packing area where they are graded according to colour, ripeness and size. They are also inspected for various quality parameters, before being packed in the required packaging. In this way we can supply our customers with tomatoes that perfectly match their needs. In September we remove the growing tip at the top of plant, so it doesn’t produce any new flowers. This promotes the ripening of the remaining vines on the plant. At the end of November, the cropping cycle stops. The plants are removed, and the greenhouses are thoroughly cleaned. Ready for a new team of top performance athletes.
Biological crop protection
Working with nature is the only way to produce healthy and safe food. We are committed to maximum deployment of biological crop protection by maintaining the natural ecosystem in the greenhouse. We use natural predators to protect the crops from pests and diseases. For example, ladybirds that eat the leaf aphids and parasitic wasps that control the greenhouse whitefly population. Biological crop protection is circular and does not affect the environment. In addition, the plant’s natural defence system is boosted, and they are less susceptible to disease.
Harvesting rainwater
Our main source of water to irrigate the tomato plants is rainwater. Rainwater that falls onto the greenhouses is harvested, or collected, in large tanks. In winter, excess water is injected into a sandy soil layer at a depth of about 40 metres. The water is stored there between several layers of soil, so it is isolated as a large ‘bubble’ and protected from contamination. In dry summer periods, when the water is needed we can pump it up again.
All the water we harvest is used as efficiently as possible. Intelligent software identifies the precise water requirement of the average plant, so they are never given too much or too little water. Any water not absorbed by the plant is drained away, filtered and reused. This closes the water use cycle.
Substrate-based cultivation
The tomatoes produced by Duijvestijn Tomaten are grown on a substrate medium made from stone wool. Stone wool has a unique fibre structure, which enables very precise dosing of water and nutrients. This means that waste is practically eliminated. In addition, stone wool can easily be reused. It can be recycled to make new substrate slabs but is also ideal as insulation for homes or as a filling material for bricks. This makes stone wool a sustainable and environmentally friendly product.
Energy
As one of the first growers in the Netherlands, we have heated our greenhouses with geothermal heat since 2011. Geothermal energy is a very environmentally friendly way to generate heat. Using geothermal energy means we do not use fossil fuels and there is no residual waste. This saves approximately 6 to 7 million m 3 of natural gas annually. In addition, since 2019, an array of more than 2,500 solar panels has covered the roof of our packaging division LogiFour. This enables us to generate almost enough energy to be self-sufficient. So our tomatoes are truly sustainable in every sense!