Home Posts Tagged "sustainability"


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Don’t throw away your old shoes before you get new ones – that’s an adage the Dutch sweet pepper grower Stephan Persoon firmly believes in. Now he and his cultivation manager Roel Klapwijk are putting out feelers in the direction of Next Generation Growing, and instead of replacing the old screen fabric they decided to install a second climate screen under it. It took a while to work out how best to install it.

The first green peppers have been harvested at Personal Vision in Bleiswijk. The new season is just around the corner and changes are in the pipeline in Stephan and Thea Persoon’s 7 hectare nursery with their son Roy having recently joined the team. They grow three main varieties of red peppers and they are also trialling several new varieties from various breeders. This broad palette is a good reflection of how the company works. At Persoon they manage their own sales without the intervention of a growers’ association. Every customer has their own preferences and with several different varieties in house, Persoon can meet all their requirements.

Crop manager Roel Klapwijk has been part of the team for ten years now and specialises in climate control. He attended one of the Next Generation Growing (NGG) courses and came away with several new ideas. Like many sweet pepper growers, Persoon listened to what was being said and let it all sink in for a while. “I built up my whole cultivation strategy around my own experience and intuition. It’s hard to just let that go. I can see that the younger generation doesn’t carry this ‘baggage’ around with them!” he says.

Second screen

Nonetheless, he is open to change and therefore to NGG as well. So last year Klapwijk started to experiment a little with their existing energy screen, above a variety that happily stays generative. He allowed the temperature to rise slightly higher there, except on the hottest nights.

Last winter the time had come to make some changes to the screen system, which plays such an important role in the new cultivation strategy. “We were planning to replace the old fabric”, Persoon explains. “But then we began to question whether that was such a good idea.” In their ten-year-old greenhouse with a six metre post height they have a Luxous 1243 D screen, says Ton Habraken from Svensson. It was actually working well in combination with a fixed AC foil at the start of production. Although it had seen a lot of use, it was not particularly worn and was technically still in a reasonable condition.

After the NGG course, it began to dawn on Klapwijk: why not add a second screen? It didn’t take them long to decide. Persoon: “We took the plunge and decided to leave the old diffuse screen in place and install a second screen, a clear energy Luxous 1347 H2no FR, underneath.”

Halfway up the trellis

That decision was not the end of it, however. The big question was where the second screen would go. The original wire bed is on top of the 12.8 m wide, 58 cm high trellis girder. Placing the second screen at the bottom would leave a gap of exactly the same width as the one above the first screen, allowing plenty of room for air movement.

“With the single screen, AC foil and horizontal fans we already get too many temperature differences. That’s what we want to avoid,” Persoon explains. He was already trialling moving fans around to better control air distribution in the greenhouse. He also fitted 150 sensors to measure the temperature distribution in the greenhouse.

Working with his regular fitters Steetec, he came up with a system in which the second screen would be installed halfway up the trellis, reducing the distance between the two screens to just 25 cm. The screens now close towards each other. Some modifications were needed to the drive shaft, the reverse wheels on the pull wires and the cross braces in the greenhouse. To reduce draughts above the screen, four vertical partitions were fitted along each bay in the 211 metre wide greenhouse. The growers hope that these measures will at the very least make things “calmer”.

Radiation meter

They also installed additional measuring equipment. There are now two sensor units measuring the temperature and RH above the screens. This enables Klapwijk to keep track of exactly what happens when the screens are closed. An RH meter and a radiation meter that records outgoing radiation into the sky were fitted on the weather station.

The screen can be closed on clear nights with high outgoing radiation, although that isn’t always necessary when there is cloud cover. The time of year is irrelevant: “Clear nights in summer sometimes produce more outgoing radiation than in winter,” Habraken explains. “On the other hand, in cloudy conditions there is sometimes very little difference between incoming and outgoing radiation. In that case, it’s often better to keep the screen open.”

Thermal imaging camera

The nursery has been using an infrared plant temperature sensor ever since it started out in 2006. A thermal imaging camera has now been added which measures the vertical temperature distribution in the crop. Klapwijk: “We know there are differences, but now I can really see what’s going on.” He doesn’t yet use the information from the camera to steer the crop because he wants to wait a while to see what happens in the crop first. “I expect to start using this information as a steering tool later in the season.”

Ultimately the cultivation manager will be able to decide what action to take based on measurements taken in the canopy and at the head of the crop. He will also be able to ascertain whether the temperature of the flowers or fruits is dropping below the dew point. The LetsGrow climate monitor tells him what is going on in real-time.

New climate regime

Last year the growers decided to apply a diffuse coating to some of the glass. Klapwijk: “The crop has become slightly more vegetative under the coating.” With this experience in the back of their minds, they will soon be applying a diffuse coating to the whole greenhouse to allow the light to penetrate further into the crop. The next step is to gradually implement a new climate regime. “We are already closing the screen at the end of the day more often, and we are making sure there isn’t too much vegetative growth.”

The question is whether the sweet pepper growers are ready to try growing at a higher temperature, as advocated in NGG. According to Persoon, that decision depends on the plant balance. If the plant load is too high, he doesn’t think they will. Or perhaps the higher temperature might actually help the fruits ripen more quickly. All in all, it looks set to be an interesting pepper season.


Personal Vision in Bleiswijk in the south of the Netherlands installed a second screen with clear energy fabric in March. The old diffuse fabric in the existing system has not yet been replaced. With this combination, the sweet pepper growers want to gradually apply the principles of Next Generation Growing. By installing the second screen halfway up the trellis girder, they aim to reduce air movement between the screens and ultimately improve the temperature distribution in the greenhouse.

Text and images: Pieternel van Velden.

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Water. It’s essential for everything that grows and blooms anywhere in the world. And of course greenhouse horticulture is no exception. But with the advent of new, improved cultivation techniques and innovations, our sector is perfectly placed to use the good quality water we have at our disposal sparingly and carefully.

Columnist Herbert Stoker in South Africa has already written about the water problems in the Cape Town area in the south-west of the country, which are forcing growers to revisit the way they use water. As a result, drip irrigation is very much on the up. And even though there is plenty of rain in other parts of southern Africa, filling farmers’ reservoirs and gardeners’ water butts, attention needs to be focused on water there too. The burning issues are: How do you handle water flows to which nutrients have been added and which contain crop protection residues? And how will this impact on the soil, flora and fauna, and human health?

Here in the Netherlands, water treatment is one of the key issues facing greenhouse growers. As of 1 January this year, all Dutch growers are required to treat their water before discharging it into surface water. They can do so using their own fixed water treatment unit or a mobile unit, or they can use shared facilities. The third option is a closed system in which the water is reused and not discharged at all. This government measure currently only relates to crop protection products, but fertilisers are due to be added over the next few years.

In the European Union, environmental commitments such as these are still not harmonised but every member state will have its own targets and regulations in this area. Some countries have gone quite a bit further than the Netherlands and others are set to follow soon. Although the 1 January 2018 deadline was known about for some years, many growers only took action at the last minute. Researchers, advisers and suppliers delivered a masterpiece which growers on various continents can benefit from. After all, as Bob Dylan once said, “The Times They Are a-Changing”.

text: Roger Abbenhuis.

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Wasting water is so yesterday! The water treatment requirement that entered into force in the Netherlands at the beginning of this year is forcing Dutch growers to reduce the volume of drain water they discharge. But there is scope to reduce it even further by optimising filter output. Making minor adjustments at the front end of the system can have a significant impact on the volume of residual drain water. What’s more, keeping this volume as low as possible can ultimately save you a lot of money on the cost of water treatment.

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Levels of production of crops such as tomato and aubergine have increased in recent years with the use of rootstocks. In a number of other crops, such as pepper and cucumber, rootstocks are mainly used to prevent problems with soil diseases in organic production. The benefits of using grafted plants are already well known, but there is still a lack of knowledge of the interactions between scion and rootstock in different conditions and how to control them.

A group of experts have now compiled all the available knowledge in this area in a book called “Vegetable grafting: principles and recent practices”. It not only covers the latest scientific insights but also provides a lot of practical information on grafting methods, choice of rootstock and the use of grafted plants. It also features recommendations from researchers at the Greenhouse Horticulture business unit on how to best utilise the benefits of grafted plants during production.
This book can help to increase the production, quality and sustainability of grafted vegetable crops.

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Thanks to high production levels, a reduction in the use of crop protection agents, the reuse of waste materials and a low percentage of food waste, the Dutch agricultural industry has the smallest ecological footprint in the world. So concludes ABN AMRO in its online publication Agrarisch: circulair van huis uit, loosely translated as ‘The agricultural industry: circular from its very roots’.

The ABN AMRO bank has compiled a list of the cleanest and most polluting countries in the fields of agriculture. Nevertheless, Jan de Ruyter, sector banker at the Dutch Central Bank, confirms that it is almost impossible to rank all crops. “A great deal of research has been done, but this is highly fragmented. It is only when you put all the studies together that you are able to draw a coherent conclusion.”

Little waste

ABN AMRO’s claim that the Netherlands has the least polluting agricultural industry is based – among other reasons – on the high labour productivity, the limited use of chemical protection agents and antibiotics. The decline in the number of chemical protection agents used and the use of antibiotics has its roots in the strict legislation imposed by the Dutch government. Dutch legislation has therefore produced the desired effect with regard to curbing pollution within the agricultural industry.

Smart farming

In addition to this, the industry has been making use of residual and waste flows for many years. As such, a very limited quantity of raw materials is lost. Waste is also combated by making frugal use of raw materials and efficient food production. This efficient cultivation method owes its success partially to the use of sensors and data analysis: also known as smart farming.

Renewable energy

What also contributes to the small ecological footprint is the fact that farmers and horticulturists in the Netherlands are involved in the production of at least 42% of the renewable energy in the Netherlands. Many greenhouse horticulturists also use sustainable energy sources such as residual heat and solar energy. A total of 4.9% of all the energy in the Netherlands is used by the agricultural industry.

Source: ABN AMRO.

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Sjaak van Schie, of Maasdijk, in the southwest of the Netherlands grows hydrangeas that vary in size from minis to large plants, with a large flower ball of at least 30 cm diameter, from soft pastel colours to hard tints. In his office the visitor cards highlight how over the last few years the nursery has become more focused on the production of rooted and unrooted cuttings from this wide range of plants.

Sjaak van Schie began growing dianthus in 1980 in Honselersdijk, Westland. At a certain moment he had 5 ha in the Netherlands and a nursery in Portugal producing these flowers. When the dianthus market changed due to strong competition from overseas he looked for an alternative product. He decided to choose something that couldn’t be so easily transported by air – to reduce the competition – and came upon the hydrangea.

Ten year plan

He took it seriously from the start and made a ten-year plan to achieve his goal via his own propagation from cuttings. Towards the end he started to breed as well. “When I realised that I hadn’t started with the right partner with respect to breeding, doors opened at other breeding companies. I was able to observe what they were doing and saw opportunities. Conversely they saw that as a propagation company I produced many cuttings. Through me they had a good sales channel and could receive a lot of royalties.”
Today the grower supplies a wide range, from unrooted cuttings to flowering plants. Van Schie annually receives virus-free laboratory plants which he cultivates into mother plants.

Domestic and abroad

Today his facilities in the Netherlands comprise a 12 ha greenhouse and 24 ha for containers outdoors. In addition, in St. Isidro de Pegões, Portugal, he has a 24 ha field for containers and a 6 ha greenhouse. Within this, 1.5 ha is assigned to mother plants, 2 ha for rooting and 2.5 ha for the pot plants Dipladenia and waxflowers that he grows to spread his risk. In Uganda is another nursery of 1.5 ha for mother plants from which only unrooted cuttings are produced.
“We root about 40 per cent of the cuttings ourselves. We sell the unrooted cuttings to other nurseries. Of the rooted cuttings 30 per cent are sold and the rest are grown on to the end product.” In Portugal this specialised nursery has stopped producing hydrangeas as an end product. “We were competing with our own end customers. They said they would only buy half finished plants if we stopped. In the Netherlands we only cultivate the new products through to end products. This is just 10 per cent of the amount of end product we used to sell.”


Ultimately he only wants to cultivate his newest and most special ‘Hy-pe varieties through to the end product. The name is a combination of Hy-drangea and the Portuguese origin of the plants. ‘Pe’ means ‘at the foot of’ and indicates the production site in Portugal. This line includes the products ‘Avantgarde’ and ‘Double Dutch’.
“I visit, together with my sales team, all the breeders in Europa. I can choose the best types and for a part I receive the exclusive sales rights. Firstly we try out the new varieties in small volumes to prevent them being swallowed into the mass. As soon as the top segment picks up on them the rest follows, says Van Schie from experience.
Characteristics that the grower looks for are nice flower colour, double colours, special leaf, good vase life, reduced stress susceptibility and a strong plant. The plants are aimed at the garden and houseplant market and it doesn’t matter in which country. “It is a popular plant that does well everywhere.”

Tight schedule

The daily life of this motivated businessman has a tight schedule. “My secretary keeps a perfect agenda.” This has to be the case because he has to divide his time between the nurseries in
Maasdijk and Portugal. “I’m two weeks in the Netherlands and one week in Portugal. In addition I visit clients in Scandinavia, Germany, England, Italy, Portugal, Spain and France. Clients from all over Europe visit while I’m in Portugal. Luckily I have a very strong sales team to support me.”
The daily running is in the hands of a Dutch-Portuguese team of people. The business in the Netherlands is staffed by around 60 permanent employees and about 70 extra temporary staff during the peak periods. Some 75 employees work in Portugal plus around 90 temporary staff during peak periods who take cuttings and pick up plants. The branch in Uganda is managed by JP Cuttings.


The grower uses the production nurseries in the different countries to his advantage. Half finished plants from Portugal arrive on the market later in the season but have a better shelf life. “The Dutch half finished plants are ready earlier but have a shorter shelf life. In Uganda we only produce unrooted cuttings.”
The Portuguese nursery is run by a Dutch management team. The Portuguese work well and do mainly the production work. “Regarding safety the same rules apply here as in the Netherlands. The tax situation is somewhat different. Social security is at a high level in Portugal. The salaries are lower and the tax too. This rises progressively with the rise in income.”


Up until last year Van Schie still sold end product in Portugal. Therefore he still has a reasonably good picture about the Portuguese consumer’s ‘idea of quality’. “The Spanish and Portuguese really buy on price. They want a reasonable quality but not the same as that required in England or Germany.”
The average buyer, who does not do business with Lidl or Aldi, doesn’t ask questions about sustainability. “Three years ago growers could still use methyl bromide. They are 20 years behind. The EU quickly brought that to an end. They are now about five years behind. That’s not a problem for me. I know what’s coming because a lot of business has already been filled in.”

Price determining factor in the Netherlands

Sustainable production is the grower’s hobbyhorse. He does everything possible to produce a beautiful and sustainable product. But he’s not very positive about the value placed on that in the Netherlands. “Supermarkets talk about healthy and environmentally friendly products but, when it comes down to it, price is the determining factor. But because of the supermarkets we no longer use undesirable substances.” It costs the production company money and energy to make that happen.
“Our problem is that the rules are made by non-growers without any feeling for cultivation. The black and white actions by Dutch supermarkets therefore cause a lot of frustration. In other European countries such as England, Germany, Scandinavia and Switzerland we can ask certain clients to pay more for sustainably cultivated products.”


Sjaak van Schie produces rooted and unrooted cuttings and half finished hydrangea plants in Portugal, Uganda and the Netherlands. In the Netherlands he also grows some of the plants through to fully flowering end products. These include the Hy-pe range, a top line through which he introduces new hydrangeas to the market. The company puts a lot of emphasis on sustainability although, particularly in the Netherlands, supermarkets don’t value this enough.

Text and photos: Marleen Arkesteijn

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‘Internationalisation is crucial to us’, explains Meiny Prins, CEO and co-owner of Priva, and Businesswoman of the Year 2009.

‘Priva is a family-owned and operated company that supplies climate control products and services. We serve two markets: the built-up environment and production horticulture. We offer measuring and control equipment that will enable its users to achieve the highest possible returns with the least amount of energy possible, and while using the greatest amount of recycled water possible. Our knowledge in the field of horticulture is based on two components: our expertise in the field of measuring and regulation, on the one hand, and our knowledge of plants, on the other. We know precisely what each plant needs and are able to coordinate our parameters to these requirements. This is also the difference between the two markets. There are a lot of variables in greenhouse horticulture, but a greenhouse is also a kind of intensive care unit. If something goes wrong, all the plants in it could die within an hour. This process is not as critical when it comes to buildings; we usually don’t complain unless it’s too hot.

'To keep a leading edge with regard to technology, over 150 of our 450 employees focus on product development, which is an aspect in which we invest a quarter of our revenue.'

‘Our exporting activities are also crucial. To keep a leading edge with regard to technology, over 150 of our 450 employees focus on product development, which is an aspect in which we invest a quarter of our revenue. The Dutch market is too small to bear these costs, let alone the risks of a possible crisis on the market. A workable distribution of risks is, in any case, important. We have to offer our employees a solid foundation. It takes three years to train a salesperson to be sufficiently knowledgeable with regard to our technology, for example. Training a service engineer takes five years, and the training programme for a project engineer takes a full decade to complete. When you invest as heavily as this in people, you can’t suddenly cut costs and then decide to expand immediately after. We sell our products for the horticulture industry in over 100 countries, we have 10 branch offices and supply our products to 140 specialised installation professionals worldwide. Our dedicated consultancy services, however, are still offered only from our head office in De Lier.'

‘As I mentioned previously, our exporting activities were relatively easy to get off the ground, as we are active within two sectors in the horticultural industry. It comes down to simply travelling along with your customers. In the course of time, Dutch growers have been relocating to all corners of the globe. I could even go so far as to say that every greenhouse horticulture project launched today, no matter where in the world, has a Dutch person or firm somehow connected to it. Growers become used to working with specific equipment when they were still in the Netherlands, and want to continue using it at their new location.'

‘The situation is entirely different in the building and construction industry. In this case, we moved from country to country, conquering our niche in the market as we went along. The first country we established a new branch in was Germany. This was not the easiest place to begin, as it was also the home base of many of our competitors in the building management system sector. It may not have been the best choice at the time. We currently have ten offices in such countries as Canada, the UK, Belgium and China.'

'Our new strategy focuses more on “verticals”, specific groups of customers.'

‘We are, however, planning to adjust our strategy, because this approach simply takes too long. It takes five to seven years for a newly established branch to start generating a steady profit. This procedure is too expensive, and too slow for building up a global network. Our new strategy focuses more on “verticals”, specific groups of customers, with scalable solutions that we can develop for specific segments and can subsequently roll out on a global scale. Examples include climate control in supermarkets, or operation rooms.’

Many business enterprises with a focus on exporting activities employ stringent selection criteria from the very start. All applications that do not immediately fall within a specific niche are not followed up on. What is Priva’s strategy in this?

‘Of course, we will look into the application, and do follow up on practically every lead except for in specific cases. What is an important point for consideration is that we are the absolute market leader in our segment. What we want to prevent under all circumstances is getting the reputation of being slow - or, even worse, arrogant.’

Are you personally still active in the market?

‘Certainly! My portfolio within our three-headed management team is commerce. I undertake a long journey twice a year, during which I concentrate on business development, in addition to customer relations management. My position as a CEO opens quite a few doors, and gives me opportunities to set my foot on hitherto unpaved roads. What I specifically aim to do, is to launch pilots in collaboration with businesses that play an exemplary role in the market. By using our equipment and accurately calculating the results and, above all, communicating clearly, we are able to convince other companies of the advantages of our technology much faster.'

You are unlike many other CEOs because you are actively engaged in marketing your firm’s products. Many companies these days are led by spreadsheet experts, and not by people who still play an active role in the market. What’s your opinion of this?

‘I’m not such a big fan of spreadsheets. If you start making calculations, you have to use them sooner or later and most often that will mean cutting costs. After that, it takes about a year to straighten out the consequential damage. What’s more important is that, if I were to start working that way, the rest of my business would be prone to following my example. Before you know it, everything will be directed at internal operations, and that’s not what I want at all. I - and the same goes for the rest of my company - prefer to direct my energy outwards.’

'“Adding value” is our motto, and if I succeed in doing this for another decade, I’m satisfied and will take it from there.'

Meiny Prins is a fervent supporter of the circular economy. She launched the ‘Sustainable Urban Delta’ initiative, a string of pearls in the field of water, food, energy and knowledge.

Is this a personal hobby, or does this tie in with your company somewhere?

‘Sustainability is never a mere hobby; it is a significant theme that deserves the same status as quality. I firmly believe that whoever can offer integrated solutions will have a leading edge on the competition. And that it is important to have a vision for the future. More and more people are drawn to living in a cosmopolitan environment, to urbanisation. This means that the waste water produced by these people will have to be used for the production of food. Waste derived from food will, in turn, be used as biofuel, and residual heat derived from greenhouses to warm residential areas. All of these systems will be scaled downwards, and inter-coordinated. As control is our business, we’re already engaged in developing the next generation of control equipment, in which we don’t take only the greenhouse or building into consideration, but also look into how we can coordinate our system to the processes going on in the direct environment.’

You are the co-owner of a successful business. What are your plans for Priva in the next 50 years?

‘I can’t think that far ahead! My motivation stems from the ability to provide added value. Following in the footsteps of my father, money is not a goal onto itself. Every euro is reinvested in the company. “Adding value” is our motto, and if I succeed in doing this for another decade, I’m satisfied and will take it from there.'

‘It’s not without a reason that I say a decade: these days innovations come and go at such a rapid pace and have such a gigantic impact that added value is the key to survival. Even stronger, everything that is not capable of contributing some sort of added value is disappearing or will be disappearing. This shift is more far-reaching and faster than gradual technical developments. In our niche of the business, we are already referring to what we call “disruptive innovations”, and “game-changing inventions”.'

'It is far better to develop your own Uber Taxi and retain control over it than to relinquish it to the competition.’

‘Within Priva we have already developed all the knowledge we need to cannibalise our own products. If we were to introduce our new concepts on the market, our own sales figures would drop by half. But that’s not what it’s all about; you can also think in terms of possibilities. By considering new markets to tap into, for example. Of course, you don’t really have a choice: if you don’t jump on an initiative, someone else will. It is far better to develop your own Uber Taxi and retain control over it than to relinquish it to the competition.’

This interview was made possible by Tuinbouwvertalingen.nl. Photo: Priva.