Home Posts Tagged "greenhouse"


1.07K 0

With the second crop in the Winterlight greenhouse at the Energy Innovation and Demo Centre (IDC) in Bleiswijk (NL) coming to an end, it’s time to draw some initial conclusions. The predominant feature of the greenhouse is its extremely high light transmittance.

Growers don’t only stand to gain from this in the winter but in the dark autumn months too: the 10%-plus light gain the designers were aiming for has turned out to be a reality. This not only means that all the partners involved in the project did a fantastic job, but also that the models used in the design process, such as RAYPRO, have proved their worth.


On the crop side, the two high-power crops we grew also yielded good results, despite the thrips problems we had in the first crop. With a few growing weeks to go, the tally is currently 268 cucumbers with an average fruit weight of 407 grams, bringing the total yield to more than 109 kg/m2. We are pleased with the outcome on the energy front, too. In this greenhouse, which is single glazed and has two high-transparency screens and a dehumidifier with heat recovery, we used less than 20 m3/m2 gas between the end of December and mid-November. But this did mean that we had to buy in around 13 kg of CO2.

1.82K 0

Greenhouse builder Debets Schalke has a built one of the largest greenhouse for the cultivation of algae in the world in Austria. The greenhouse has a surface area of one hectare dedicated to the annual production of 100 tons of biomass derived from dry algae. When the full expansion of the greenhouse has been achieved in 2021 production figures will run to 300 tons per year.

The production of microalgae is a lucrative enterprise; the total turnover from the production of microalgae comes to billions of euros worldwide. Algae are relatively easy to grow and contain a high amount of high-quality fatty acids (Omega 3 & 6), natural colorants and valuable proteins.


The greenhouse built by Debets Schalke was tailored to the provide algae grower eparella with the facilities necessary for year-round production. A greenhouse with a post height of eight metres is exceptional, but necessary to enable the bioreactors that produce the industrial micro algae to operate to the best of their ability. Additionally, the greenhouse makes use of large ventilation systems to adequately regulate the extremely warm land climate in the greenhouse.

Versatile raw material

The microalgae grown by eparella are cultivated in 43,000 glass tubes distributed across 32 production chains: the bioreactors. It is possible to produce powdered algae of edible quality all year round by growing it in bioreactors. However, eparella does not use the micro algae exclusively for the production of foods and food supplements; eparella’s microalgae are also used as a raw material for cosmetics and medicines.

Sustainable product

Because algae contain high-quality fatty acids like Omega 3 they are considered a sustainable alternative to fish oil. The production of algae does not create an imbalance in the existing ecosystems, as opposed to fisheries. eparella’s closed cultivation system ensures that the algae are grown in a pure and largely uncontaminated environment. As a result, the industrial microalgae are a clean raw material for sustainable products.

Text: Leo Hoekstra. Photo: Debets Schalke.

1.17K 0

In the past five years, the Dutch greenhouse horticulture industry has shrunk by approximately 10% in terms of acreage. As opposed to just under 10,000 hectares of land dedicated to greenhouse horticulture in 2012 (9,960 hectares), this industry’s acreage has decreased by 1,000 hectares as it stands today, according to the Statistics Netherlands. During this period, the cultivation greenhouse vegetables has increased, which automatically translates into a decline in the greenhouse cultivation of ornamental plans.

According to Statistics Netherlands, the surface area dedicated to greenhouse vegetables amounts to 4,950 hectares, just under 30 hectares more than last year, In comparison to 2012, this means an increase of 80 hectares or, in other words, a 1.6% growth. This growth can be attributed primarily to tomatoes, for which crop the total surface area this year amounts to 1,730 hectares. This is 40 hectares, and therefore just under 2.4% more in comparison to 2012.

Greenhouse vegetables are flourishing

The explosive growth of the cherry tomato is responsible for this, according to the statistics. The surface area amounts to 420 hectares this year, almost 3 times more than in 2016. This is, however, at the expense of the vine tomato, which has seen a 20% reduction, down to 970 hectares. Nevertheless, the vine tomato remains the most popular greenhouse vegetable, followed by red block peppers, cucumbers and greenhouse-grown strawberries. The acreage reserved for sweet peppers, cucumbers and aubergines remains stable, while surface area dedicated to strawberries grown in greenhouses and tunnels has increased proportionately this year: by 17.6%, up to 400 hectares.

Fewer ornamental plants

Where the cultivation of greenhouse vegetables has grown, the production of ornamental plants in the Netherlands has shrunk during the course of the past five years. The surface area dedicated to growing flowers amounts to 3520 ha in 2017, 300 ha less than in 2016, meaning a decrease of just under 8%. Between 2012 and 2015, the acreage decreased by 3.5% to 5.5%. In the past five years, the acreage dedicated to nursery-grown flowers decreased by 1,030 hectares, a shrinkage of at least 22.5%. This decrease can be attributed primarily to cut flowers. In 2012, cut flowers were grown on 2,310 hectares of land, which means that the cultivation of cut flowers has decreased by 630 hectares within the space of five years. This is a decrease of at least 27%. With regard to potted plants, the surface area decreased to 1,270 hectares: a decrease of 60 hectares or 4.5%. As from 2012, the surface area dedicated to potted plants amounted to approximately 1,290 and 1,330 hectares on an annual basis.

Source: CBS. Photo: Mario Bentvelsen.

828 0

Interest in artificial lighting with LEDs is on the rise. Recently tomato growers Verkade in ‘s-Gravenzande (Westland, the Netherlands) gained their first experience with a hybrid system consisting of SON-T HPS lights and LEDs in a greenhouse that is too low for intensive lighting using only SON-T lights. Growing manager Fred Schäpe is happy with the winter yields. Based on his first impressions, he believes this system could deliver even more. He is pleased with how things are going.

It’s the middle of summer. At Verkade the LED interlighting modules are often still on at 11 am, depending on the climatic conditions. They can be switched off after midday. In his first year with this lighting system the growing manager is already exploring how far he can take things. By taking a good look at how other growers are using artificial lighting, he is learning fast and making his own plan.

Low greenhouse

In the autumn of 2015, an artificial lighting system was installed at this ‘s-Gravenzande-based tomato grower’s 4.4 ha site with the support of the growers’ cooperative Van Nature, in order to meet rising customer demand for Dutch products of consistently high quality all year round.
The Venlo greenhouse has a bay width of 8 m and a post height of 4.85 m, which is too low for intensive lighting with SON-T lights because of the amount of heat they emit. “We could also have raised the height of the greenhouse, but a combination of SON-T lights and the cooler LEDs proved a better option in the end,” Fred Schäpe explains.
After much discussion, the two organisations decided to install a hybrid system. At the top they installed Hortilux 1,000 watt SON-T downlights delivering 135 µmol/m2/s. These lights are distributed in threes along the width of the trellis girder. The distance between the light and the tops of the plants is 1.2 m, reducing to around 1 m as spring arrives.
One strip of 55 µmol/m2/s LEDs was suspended between the plants in each row and can be moved as the plant grows taller. A total of 6,610 Philips GreenPower LED interlighting modules have been installed, bringing the system’s total output to 190 µmol/m2/s.

Start of growing

Verkade specialises in large cluster tomatoes. Fred Schäpe has always grown Merlice. In midsummer the plant load is spectacular – an image that is only enhanced by intensive leaf pruning which makes the trusses stand out even more.
The 64-day-old grafted and topped plants were planted at the end of October. At first the plant density was 2.3 per m2. A lateral stem was allowed to develop in week 46, increasing the density to 3.05 per m2. The last lateral stem was added in week 48, bringing the final density to 3.8 stems per m2. Production started in week 52.
Immediately after planting, the plants remained unlit for ten days, after which the light level was gradually increased. In the lighting season, which lasted until around 1 April, the SON-T lights were left on between midnight and 6 pm. They were switched off when the radiation reached 2,000 J/m2, so the number of lighting hours was lower in April.
Unlike the SON-T system, the LEDs are left on constantly from 4 am to 5 pm from 1 April onwards, except on very hot days when the system is switched off earlier.

Effect on truss development

At the start of cultivation the interlighting strips were hung as low as possible in the crop. Later on they were repositioned once, close to the developing trusses. The growing manager is already coming to the conclusion that he will have to move the modules several times over the course of the next crop to keep up with the trusses and to enable every set truss to get maximum benefit from the light. Schäpe: “We do this manually. We want the trusses to develop as well as possible with maximum plant load.”
By about week 50 the modules were in their highest position and were left there for the rest of the growing period. He soon noticed the positive impact of the LEDs on truss development and flowering speed. “Trusses seem to be developing a little better with LEDs than with only SON-T.”
In January last year, Schäpe was happy with the crop status. “It’s all going well,” he said at the time. “The crop has been steered generatively right from the start, and I can see that the plants are having no trouble putting their energy into the fruits.” He is happy with the winter production, and although it is only their first growing year, he looks ahead with optimism: “With the knowledge we gained last winter, I’m sure we will be able to do even better in the future.”
The crop manager has his own strategy for truss pruning and fruit load. Sometimes he prunes the Merlice to as many as six fruits if the truss is strong enough. By doing so he is looking for the ideal fruit load.

Heavy investment

Looking back at his first season, Schäpe is positive about the impact of the LEDs on production and quality. Although it’s a heavy investment for large cluster tomatoes, Schäpe sees even more potential in optimising the crop even further. Only time will tell. But for the time being he can look back over his first season of artificial lighting with a smile.


With support from the growers’ cooperative Van Nature, a hybrid lighting system was installed at one of tomato grower Verkade’s sites in Westland, the Netherlands, because the greenhouse is too low for intensive lighting using only SON-T lights. Crop manager Fred Schäpe is happy with truss development and flowering speed. Although this is only their first year of artificial lighting, the company is pushing the boundaries in order to optimise growing.

Text and image: Pieternel van Velden.

879 0

Van der Avoird Trayplant, in the south of the Netherlands, made such specific demands on the greenhouse ventilation that the builder’s computer program was not able to figure out the optimal design. Therefore, based on estimates, a unique greenhouse complex was built that appears to work well. The design of the new site was carried out together with the local residents.

The 1 ha greenhouse looks very normal but looking at its crossways you see two greenhouses each 48 meters wide and 135 meters long. In between these long narrow greenhouses is a four metre wide strip of grass. Next year another such greenhouse will be built along side, again separated by a strip of grass. As well as the vents in the roof, the sidewalls can also open for maximum ventilation.

Risk assessment

In 2006 the nursery that specialises in tray plants for soft fruits built a greenhouse for raspberry mother plants and cuttings. “We had to invent everything ourselves and couldn’t copy any other young plant propagator. It was the same when we built this greenhouse last year. That makes it difficult for the bank because they can’t refer to risk assessment data from anywhere else. That makes them cautious and it’s the reason why we have to build in phases," says owner, Peter van der Avoird.
His company comprises five locations in the province of North Brabant, which together total 31 ha of tray plants and 5 ha of glass for the propagation of raspberries and strawberries. The company is the largest producer of raspberry cuttings in Europe. The greenhouse serves to bring forward the season and to better manage the production process.

Discuss with the neighbours

Sales of soft fruits are growing in Europe. The demand for blueberries, raspberries and blackberries is significantly greater than the supply. The production areas are growing strongly and the propagator is growing steadily too, about 15% annually. However, on the older locations Van der Avoird has reached its limit for expansion. “Legally we can expand in the Molenschot area but the neighbours and council wouldn’t be happy about that. Running a business in the Netherlands increasingly requires you to look around the local area to discover new possibilities,” he says.
This was how he came to find a plot alongside the motorway in the neighbouring village of Bavel; grass and corn country but with a building permit. “We could have just gone ahead and built but we felt it was important to first communicate this with the surrounding residents. I personally visited all the neighbours to explain our plans and asked them to respond to our rough sketches. This did have consequences on the location of the office, other buildings and the green area,” he says. One neighbour wanted to have the office opposite his house; another neighbour preferred to have a fence instead of a green strip and a third wanted a piece of land to be left to nature. “This all worked out well. I wasn’t bothered about the exact location of everything. We could easily move things around on the plans.” The result was that none of the local residents objected to the plan, a unique situation.

Maximum ventilation

The building in Bavel started two years ago and will take four years to complete; within two years the site will have been expanded to 20 ha, and will comprise 13 ha of field trays for raspberries, 3 ha of field trays for strawberries, 3 ha greenhouse and 1 ha of stores and office.
The greenhouses required the most creativity because there was no previous practical experience on which to fall back on. The raspberry cuttings are rooted in the warm greenhouse (of 1 ha) and after two weeks are moved to two cold greenhouses which if necessary can be heated. Here they are hardened off. This means they have to get as much air as possible. “Our most important period for delivery is April/May. You can harden the plants off to meet this deadline but because of our volumes it is too big a risk: Just one bit of frost is fatal. Therefore we need to have a greenhouse that we can heat now and then as well as have maximum ventilation,” explains Van der Avoird. This last requirement caused many headaches and brain storming sessions with the builder. One possible option was a cabrio greenhouses; a greenhouse whose entire roof can open: This was not suitable concluded the grower after making lots of calculations. “Even if the roof is completely open you still have a 7 metre high glass wall. When there is not much wind there is far too little air movement.”


Discussions with the greenhouse builder Van Amelsvoort and advisor Looije Agro Technics led to a unique solution: Both the roof vents as well as the side walls of the long narrow greenhouses could open. This combination, with the open space between the two units, created a chimney effect. As a result there is always a breeze in the greenhouse even when there is no wind.
The problem was that such an unusual solution didn’t fit into the builder’s calculation program. What should be the exact size of the greenhouse? How much energy is lost through the large number of seals in the sidewalls? What width should you make the corridor between the greenhouses? “You can calculate everything for a square greenhouse of 5 ha. Here we had to make assumption after assumption after assumption. In the end the dimensions were mostly guesswork. It did lead to some surprises: Initially we hadn’t planned to have an energy screen in the cold sections but the heat loss was much larger than expected. Therefore we had to install one later.”

Optimal utilisation

The conclusion after one season is that in practise it works perfectly. Therefore they will go ahead with the planned third cold section next year in exactly the same way. “It is a very expensive solution,” he says. “It means we have to optimally utilise the greenhouse space by having at least three crops per year.”
Also the greenhouse equipment is quite expensive. The heating, as well as a ground net with ethylene hoses every 25 cm for above ground heating is hardly used. For 3 ha of glass he has a connection for 160 m3 and that is already an over capacity. The energy screen is hardly used. “For the average temperature in April we don’t need any heating. Actually the energy screen and the heating are a kind of insurance. But we do need them, otherwise we could run into big problems. It occasionally happens that we have to use heat on one day and the next day open everything up to maximise the ventilation.”


The new greenhouse built at Van der Avoird Trayplant is very special: long, narrow and all the walls can open up to achieve maximum ventilation. It is an expensive but effective solution. The company currently comprises 31 ha of field trays and 5 ha of glass for the propagation of raspberries and strawberries. The business continues to expand. Before building on a new location the owner contacted all the surrounding residents.

Text: Tijs Kierkels. Images: Wilma Slegers

964 0

Constant innovation is the key to Metrolina Greenhouses becoming one of the largest and most successful greenhouse growers in the USA. For over four decades the family-run enterprise has continued to invest in technology including robotics, data analysis and logistics. It produces around 700 species and is currently laying the foundations for further expansion to keep up with market demand.

The 68 ha of glasshouses in Huntersville and the 70 ha for outdoor cultivation in York, North Carolina, are a far cry from the 1860 m2 that Tom and Vickie van Wingerden bought in 1972. With 5,000 dollars in their pockets the Dutch couple had just emigrated from the Netherlands to start their American Dream. Today the business is run by their four sons and has a turnover of over 200 million dollars. It produces 110 million seedling and cutting plugs per year which in turn produce 7 million hardy chrysanthemums; 6 million summer annuals; 5 million hanging baskets; 3 million poinsettias; 1.8 million bedding plant trays and 11 million perennials. And each year 5% of sales are made up of new items.

Extremely modern

But the company is not resting on its laurels. Tom van Wingerden’s motto was ‘the absence of innovation means stagnation’ and with that front of mind the family continually invests to improve all greenhouse processes. “In our newer greenhouses we have rolling tables and benches, cranes and spacing machines doing all the work,” says Thomas van Wingerden, one of the brothers with responsibility for operations. “Trays are placed on the production line and are not touched by human hands until they are put on a shipping cart. In some of the older greenhouses, someone has to push the tables around but no one has to touch the plants,” he says. The company employs around 600 full time hourly people, 150 salary and 750 to 1000 seasonal staff.
Metrolina is without doubt extremely modern: Technology is king and the brothers collaborate with highly innovative suppliers from across the globe. But with their Dutch roots it goes without saying that they acquire much knowledge and expertise from the Netherlands. They recently invested in a new sticking machine which was manufactured for them by the ISO Group. “We wanted a machine for difficult varieties such as calibrachoa and verbena and for very small cuttings that are difficult to stick by hand,” says Thomas van Wingerden. The ISO Group, of the Netherlands, had such a machine for chrysanthemum cuttings which it was able to develop further. “The machine does a much better job than we can do manually because all the cutting are stuck uniformly so we have a much better success rate.”

Ahead of the game

Trying something new is part of the family’s philosophy. “We always want to be ahead of the game so if there is something better out there we want to have it.” That’s why they are currently replacing about 12 ha of shade screens with Svensson Harmony diffuse screens which should be in place by 1 February. “We’d seen the new screens at shows and after discussing it with our growers we felt they would be worth trying in our lower-light greenhouses. They should give better light than the Solaro 50% screens, which have an open structure to enhance ventilation and offer 50% shade. These are currently installed on 60 ha and double up as energy curtains which has led to significant savings,” says Van Wingerden. “We have also installed blackout curtains on 40 ha of glasshouses. These not only block out the light they are used for insulation too.”
The summers in Huntersville are humid and temperatures range from 32ºC, down to 15 to 21ºC. The winters, however, can be cold. Average winter temperatures range from the 4-7°C). The greenhouses in Huntersville are heated by four 8 MW woodchip boilers which were installed about seven years ago when natural gas was expensive. Although the gas prices have dropped, the woodchips, which come from a 50 mile radius, still make good business sense, he says. “They are still cheaper than gas and they are renewable so it’s better for the environment.” About 60 ha of the greenhouses have hot water pipe floor heating that has a capacity for some 19 million litres.

Renewable energy

While 6 ha of greenhouses are Venlo types with fan and pad cooling the majority are MX open roof greenhouses. As new houses have been added over the years they have become taller, the highest being 6.7 meters, to accommodate the robotic cranes that lift and move the trays of plants and the sprayer crane, another innovation that has improved efficiency. “The electrostatic sprayers put an electric charge on the chemical particle so that it sticks on the underside of the leaf where the bugs tend to hide. It is much more efficient: We use at least 50% less chemical product than previously but get the same coverage.”

Ozone clean water

About 48 ha have ebb and flood floors and the water is recycled in a closed system. The other 20 ha have a traditional system and the water returns to ponds for recycling. These ponds cover some 10 ha which collect 15 million litres of water for every inch of rainfall, says Van Wingerden. “We get about 45 inches of rain per year so we have plenty of water and we’ve not suffered any water shortages over the past ten years.” That’s saying something because the Huntersville facility consumes a staggering 5.7 million litres of water per day.
All the water is filtered and for the last three years has been sanitised using ozone. “We originally filtered to 150 microns and step by step reduced this to a finer filtration of 5 microns. The next step was ozone,” he says. It made such a positive difference that the system is being upgraded and will be used more widely. “Our plants are much healthier with better root systems which has allowed us to reduce the crop cycle. For example, we have been able to reduce the production time for poinsettias by four weeks and spring crops by two weeks. Although general improvements in growing techniques might have helped we certainly feel that the cleaner water has been largely responsible,” he says.

Big data

This typifies Metrolina’s philosophy of wanting to do better every day. It’s a strategy that is extremely reliant on data. “We record and analyse everything,” says Van Wingerden. “We employ at least 15 analysts who analyze everything going on in the greenhouse and connect it via the inventory management system to data from the stores. We have to make sure that all the numbers adds up. Our in-house database is updating information from every crop all the time. We use this information to speed up or slow down crops if we notice that plants are ahead or behind schedule. We can create about 50 different climates and with the additional use of artificial lighting we can ensure that crops hit their schedule dates.”
The database platform connects production planning, finance, replenishment and inventory management right through to shipping. They supplies three customers: Lowes (359 stores), Walmart (881 stores) and HomeDepot (150 stores, perennials only). The stores provide daily sales numbers so they knows which items are selling well. “Our analysts then decide what to ship to which stores the next day, a system that also requires an extremely innovative logistical solution, including 160 of our own trucks. Not only are we a producer of plants we also take care of the end-to- end process right up to sales to remove the hassle for our buyers.”

Keeping pace with demand

New greenhouses continue to be built. “Our customers are opening more and more new stores and growing by 2% per year. We need 4 acres extra per year just to keep up with the growth of their stores so we have just started to build an additional 16 ha of glasshouses at Huntersville. These will be the MX open roof types and will be fully automated. This will take about eight years to complete but we expect to have the first crops available in two years. By then we should have completed all the concrete floors which we can use for production. The aim is to build 4 ha of greenhouses each year afterwards until it is complete.” The aim is to have a turnover of 250 million dollars by 2025.


The philosophy held by US greenhouse giant, Metrolina Greenhouses, is to perform a little better each day. It has achieved this over the last 40 years by investing in innovation. Most of its 68 ha of glasshouses are fully automated so that human hands only touch the trays of plants when they placed in the shipping truck.

Text: Helen Armstrong. Images: Ludvig Svensson and Metrolina Greenhouses

872 0

Thanks to a united effort, an educational greenhouse project has been set up in the east African country of Rwanda. Its aim is to allow businesses, knowledge centres and governments to learn about greenhouse design, cultivation and marketing. It is a process of trial and error yet necessary now that the demand for quality products from Africa is clearly growing.

The interest in greenhouse production is growing worldwide. It is a way to make a big leap in sustainable production as greenhouse cultivation requires significantly less water, fertilisers and crop protection substances per hectare or per kilo of product than open field cultivation. In addition, a crop grown under glass or plastic is protected from extreme weather conditions so the growing conditions and product quality are safeguarded.

Hardly any history

This is true in both rich and poor countries. In a country in which agriculture and horticulture has undergone limited development it is a challenge to achieve a greenhouse design that is suitable for the local conditions as well as create an effective cultivation and marketing structure. Under the so-called Smart Adaptive Sustainable Horticulture, or Smart Horticulture for short, Dutch companies are working with local partners in Africa. In South Africa this involves mid- to high-tech greenhouses and in Rwanda low-tech greenhouses.
“This is the most suitable for Rwanda. There is some covered cultivation, set up from out of Kenya, but there is hardly any history of greenhouse horticulture and no supporting industry,” says Anne Elings, of Wageningen University & Research. He is involved in the project as trainer and researcher. “The level of knowledge is also very low. This is typical of many countries that are just beginning with greenhouse horticulture. The technology itself is not the most difficult; a greenhouse can be designed for all conditions. The challenge is to get the crop growing and in particular to maintain it. This requires training in skills and competences in order to apply the technology effectively and efficiently."

Good lesson

The horticultural company Rwanda Best Company, owned by Jean-Claude Ruzibiza, carries some of the risk. The specially designed greenhouse has been constructed on his property, 50 km north of the capital Kigali. Smart is meant to improve the food supply through covered cultivation, but it is also a learning project.
“Such a pilot is an investment for Dutch businesses as it costs money, even with a subsidy, but in the long run it should pay off. They see clear opportunities. The industry looks beyond this country; they learn from the greenhouse design and what it entails for other African countries," says Elings.

Weak link

Ruzibiza’s plastic greenhouse is equipped with ridge ventilation and insect mesh. The greenhouse climate is not actively regulated, but because the greenhouse is situated at a relatively cool, high altitude that it not a problem. The crop – currently high wire tomatoes, and soon sweet peppers as well – are in pots filled with rice hulls.
“We decided on substrate production instead of soil cultivation because large parts of Africa are contaminated with bacterial wilt. Cultivating in pots requires a technological step with many consequences; watering and fertilisation are more accurate,” he says. Each pot is supplied via drip irrigation. The irrigation is computer controlled; that is possible because the power supply in Rwanda is relatively stable. Crop protection, managed by Koppert Biological Systems, is still completely chemical because there is currently a ban on the import of natural predators. This will change soon, opening up more possibilities.
“The grower is very well supported and that is also necessary,” says Elings. “You see here in practice how difficult it is when people have to come from very far away. In a tropical country the disease pressure is extreme and therefore it is essential to comply with hygiene regulations. The advice is simple: always disinfect boots, wear a protective coat and enter the greenhouse through a lock. But people are the weak link in the system.”

Local crop advisor

The greenhouse was completed in the summer of 2015. The first tomato crop had to be broken off early due to teething problems in the nutrient supply and crop protection straregy. A lot was learned. The grower took the professional decision to start the second crop with a clean slate. The current crop, planted in March, is so far going very well. “Designing a suitable greenhouse for the local circumstances is actually the easiest step. This is still the case. Explaining cultivation measures such as pruning and plant balance is difficult when there is little basic knowledge. The funding runs out after 12 months and the support will have to be phased out. It would be nice if an experienced Dutch grower in such a country, was available to give advice every week. That would make a big difference. But when more greenhouses are built perhaps the growers can help each other out,” he says.
The knowledge transfer takes place at eight similar horticultural nurseries in the region. A local crop advisor has also been hired who supervisors the grower and follows the training himself. In this way the knowledge transfer stays in the region.

Stable supply

The driving force behind the development of greenhouse horticulture is the demand for fresh and reliable vegetables. As well as the very many poor people in Rwanda there is also a growing middle class that is prepared to pay for good quality products. In addition, there are hotels, restaurants and, for example airlines, with a clear demand. “It is currently a process of trial and error. But in the longer term, such developments are necessary to meet the needs of the consumers. The middle class wants products that look good and that are grown with few chemicals. The latter is becoming increasingly important. And if you want to spray less, you certainly need greenhouses," says the researcher.
Apart from the production certainty, preserving the quality in the sales chain also needs a boost. Traditional open field tomatoes are often already overripe at the time they are sold. To differentiate from this Rwanda Best needs to handle the fruit as little as possible and put it directly into the right containers. “But the boxes cost money and may not be returned. Cooling also costs money. A stable supply of good quality produce is currently the primary focus before considering other matters such as sales under a brand name,” he says.

Market demand

LEI Wageningen University & Research has therefore also conducted a chain analysis in order to clarify the current situation and to identify bottlenecks. The researchers have made recommendations that will reduce the post-harvest losses (up to 40%).
The project clearly arouses interest in Rwanda. “The result is a big increase in interest in greenhouses. This is an interesting aspect for participating horticultural suppliers. In many African countries local and international companies are supplying greenhouses in which a lot can be improved. Market demand therefore exists. There must be opportunities for a good Dutch product that is accompanied by support and knowledge transfer, especially as governments increasingly encourage covered cultivation due to water shortages. Many teething problems have to be overcome, but if the Netherlands positions itself well, there are opportunities."

Partners working together

Within the project Smart Horticulture Rwanda, business, knowledge centres and governments are working together. Dutch companies are united in Holland Horti International. The companies participating in Rwanda are Bosman Van Zaal, Hoogendoorn, Rijk Zwaan and Koppert. The knowledge centres are Wageningen University & Research, LEI Wageningen University & Research, TNO and BoP Innovation Centre. The local consultant Green Pathways is also involved. The project is financed by businesses and the program FDOV (Facility for sustainable entrepreneurship and food security) of the Dutch Ministry of Foreign Affairs.


Dutch companies and knowledge centres are involved in the greenhouse project Smart Horticulture Rwanda. It stimulates interest in greenhouse cultivation and serves as a learning project. Greenhouse cultivation can improve the food supply in Africa and meet the growing demand for quality products.

Text: Tijs Kierkels. Images: Wageningen University & Research and Wilma Slegers.

988 0

Nearly 20 years ago two Dutch and two Belgian growers joined forces and bought an existing greenhouse in the USA. It was a chance for the Belgians to expand their business in an increasingly limited market and for the two young Dutchman to start their American Dream. Today their company Intergrow Greenhouses, in New York State, is planning to expand again as the demand for greenhouse grown tomatoes, available year round, continues to rise.

Dutchmen Dirk Biemans and Mario van Logten were already working in the USA when in 1993 they were introduced to Belgian grower John Vermeiren, of Loenhout. He was interested in expanding overseas and had already noticed that Dutch and Belgian tomatoes yielded a good margin in the USA, despite the high air transport costs. “My business partner, Dirk van den Plas, and I saw good opportunities,” recalls Vermeiren. “The amount of greenhouse cultivation was limited and a good price was then paid for greenhouse tomatoes. Tomatoes were being exported from the Netherlands – and Belgium – which despite the high air transport costs of one dollar per kilo yielded a good margin. That got us really thinking.”

Close cooperation

However, Vermeiren and van den Plas, didn’t want to emigrate. On the other hand, the two young Dutchmen who were already in the US had the necessary horticultural experience, knew the local situation well and it appeared wanted to set-up their own greenhouse. “We hit it off well and during conversations it seemed that the men would like to start their own company, preferably with one or two partners,” says Vermeiren. This paved the way for a partnership which saw them taking over an existing 6 ha greenhouse in Portageville, south of Lake Ontario in western NY. Intergrow Greenhouses was born.
The purchase was the beginning of a close cooperation based on equal financial and strategic input, which still stands firm. The two Dutchmen run the American greenhouses; Biemans looks after the general management and Van Logten is crop manager. Vermeiren and Van den Plas are shareholders in the business and act as a strategic and technical sounding board. Vermeiren and his wife Lia also have 8.5 ha of greenhouses in Belgium and are currently building a further 10 ha in Meer, for loose plum tomatoes (including San Marzano) and beef tomatoes. Vermeiren, along with Dirk van den Plas and his former manager Tom Lefevre run Hortipower, in Merksplas, and developed the 'B-to-B label' Tomeco, which serves the top segment of the market.

Established name

Meanwhile Intergrow has become an established name in north east USA. Its high value beef, on-the-vine and cherry tomatoes are well known in New York and surrounding area. Its recognisable trucks, which deliver products to the supermarkets’ distribution centres, also make a contribution.
However, it wasn’t all plain sailing. The first year was difficult, especially in commercial terms, recall Biemans and Vermeiren. “Supermarkets wanted the quality tomatoes we could supply, but as a newcomer you don't quickly have a foot in the door.” It took some time before repeat orders started coming in and buyers were prepared to make long-term contacts. That changed as buyers started to appreciate the year-round supply.
“We still do our own sales and marketing and we have direct contact with retailers and wholesalers. With some retailers we have long term agreements, even a yearly contract, and with others we sell on a shorter basis, monthly or quarterly,” says Biemans.

Further expansion

As demand grew so did the company. In 2003 it built a new greenhouse in Albion which has since been extended to 22 hectares. Intergrow is currently seeking planning permission to build a further 10 hectares in Webster, also in NY state and about an hour’s drive from the other locations. “We chose this location due to the availability of both natural gas and electricity. There is plenty of land available in the US but it’s difficult to find a property with gas and electricity,” says Biemans. They hope to start levelling the ground this autumn.
“We feel there is still growth in the market.” The share of greenhouse produce is increasing at the expense of field grown produce, says the grower. “But there are currently only a few greenhouse growers in the northeast of the USA.” Also more than a quarter of American consumers live within a day's drive of Intergrow’s production sites. As well as offering market potential, “this also fits with our philosophy of delivering fresh product to our consumers within one day. We promote the tomatoes as being locally grown in New York state although some retailers are more proactive in marketing this than others,” says Biemans.
“However, we do sense it is very important to be able to supply year-round. During the winter most retailers appreciate the greenhouse grown tomatoes which we produce using artificial lighting. About 40% of our total acreage – currently 28.5 hectares - is lit using high pressure sodium lights and if the new greenhouse gets the go-ahead that will be completely lit.”

Dutch replicas

The greenhouses are typical of those in the Netherlands. “We stay up to date with the Dutch on greenhouse equipment, packaging equipment etc. We aren’t using the principles of Next Generation Growing but we do have diffuse glass on the roof which we’ve used since 2011. We try improved varieties when they become available which tend to be the same varieties as those in the Netherlands and Belgium,” he says.
One of the biggest challenges for growers in the US is the weather. “It is more extreme here than in Belgium and the Netherlands and it is warmer for a longer period of time. We try to go into the summer with a strong crop so that the plants can withstand the weather.”

Weekly contact

Over the years the need to fly to and from Belgium and the USA has become less but the contact between the partners has by no means diminished. Thanks to enhanced means of communication they still hold weekly conference calls and receive cultivation support from a distance from colleagues at Horti-Consult in Deurne, the Netherlands.
Both Biemans and van Logten travel to Belgium once or twice per year and vice versa Vermeiren and van den Plas visit the US once or twice to discuss cultivation techniques and investment in technical equipment. The more information you can share the better it is,” says Biemans.


With the support of two Belgian growers two young Dutchmen started a greenhouse in the United States in the late 1990s. Since then Intergrow Greenhouses has grown from 6 to 28.5 ha, at two locations. They hope to start levelling the ground for a third greenhouse before the end of the year. The greenhouse supplies beef, on-the-vine and cherry tomatoes to retailers in north east USA.

Text: Jan van Staalduinen en Helen Armstrong
Images: Intergrow and Jan van Staalduinen

783 0

Good air circulation in the greenhouse is an energy efficient alternative to using the minimum pipe rail for growers working with Next Generation Growing. But fans come in many shapes and sizes and how well do they work? They are often not checked to verify if they have the desired effect. Measurement is key: A smoke test quickly shows how the air is moving. Suppliers would like to cooperate and furthermore they recommend that equipment is properly maintained.

If you want to read this content you need a subscription, or log in when you already have a subscription.

998 0

China’s increasing awareness of food safety and food security is driving development of more modern and efficient cultivation systems. Over the last 15 years many new ‘high-tech’ greenhouses have been constructed, often with help from local subsidies. However, in many cases they are not adequately equipped and growers still lack technical expertise to make them work. With a growing trend to hire in expert advice some of these nurseries are becoming productive.

The majority of China’s horticultural crops are still produced using traditional, somewhat primitive methods but there is a growing desire to master high tech systems. An increasing shortage of resources such as clean water and energy cries out for more efficient production and at the same time consumers are demanding for safe, quality products.
In response, government and local authorities have subsidised many new greenhouses to improve land utilization, create better environmental conditions and reduce the need for chemical substances. However, the potential of many high tech projects has been wasted due to lack of knowledge: Splinter new glasshouses have been left desolate after a failed crop. Now there’s a trend to revitalise some of these greenhouses using foreign-based expertise.

Solar still common

The most common greenhouse in China in still the traditional solar greenhouse, a half plastic tunnel fixed to a single wall. Each solar house covers around 1 mu (0.667 ha) and usually several are built close to each other in an agricultural zone. These solar greenhouses are mostly found in the north of the country where the temperature can drop to -15ºC and even to -40ºC in the winter and rise to 35-40ºC in the summer. Despite the extreme cold, plants survive because the temperature inside remains relatively warm (10ºC), even without heating.
Sometimes growers store heat in the soil wall during the day and release it at night. But these greenhouses are not productive during the peak of the summer when the temperature becomes too high.
Some air vents are present in the roof but air circulation is poor and the climate is difficult to control. Plants are usually grown in soil and crop protection products are used regularly which results in reasonable yields but at extra cost.

Not profitable

In southern China, where it is much warmer, growers tend to construct plastic tunnels that require little investment. Again, no climate control is possible so in winter they are far too cold and they are very vulnerable to storm damage. “We do see an increase in solar greenhouses, and to some extent tunnels, but it’s the high tech greenhouses which are really growing,” says greenhouse consultant, Lifeng Peng, of Delphy China. This is an international organization for horticultural advice, training and research based in the Netherlands.
“More local greenhouse constructors are becoming established and the advantages are better environmental control, high and efficient utilization of land and less pests and diseases. However, the main problem is the operation. Growers may achieve a slightly higher yield than in a solar greenhouse but it is still a third to a half of that in a greenhouse in the Netherlands which cannot compensate the investment.”
Another problem is that the new high tech greenhouses are scattered over the entire country. If they were concentrated in one place growers could jointly establish an infrastructure and share resources, such as gas pipes or water purification units, and colleagues could more easily exchange knowledge.

Appearance is deceiving

Made from glass or polycarbonate, these new greenhouses appear similar to typical Dutch greenhouse. However, it’s a different story inside. Some have very little equipment or they have systems which growers don’t know how to use. “Some growers have installed locally produced irrigation systems but these did not always work too well. Others simply don’t have the knowledge to use the equipment to make the greenhouse productive. That’s where we are trying to help,” says Peng.
She admits it’s very difficult to change the mindset of the people running the greenhouses but has recorded a success at the Blue Horizon nursery in Shandong province, north east China. The nursery was established early 2013 by a big private group which has diverse interests including hotels.

Reconstruction design

It built six separate polycarbonate greenhouses each of 2500 m2 although actual growing space is 1500 m2, the rest is taken up by concrete paths and heating pipes. Four of the houses are growing dragon fruits, seedlings and pot plants but two had been virtually abandoned after the debut crop of strawberries failed.
In October 2015 Delphy was invited to do a reconstruction design with the goal to produce cherry tomatoes and medium sized tomatoes. “When I arrived these houses looked very neglected and had in fact been empty for nearly three years. The first thing we did was change the black soil covering to a white one because it was very dark inside. We would have liked to replace the polycarbonate roof with a glass but that would be too heavy for this construction.”

Yield improved

The greenhouses were changed from soil cultivation to cocopeat slabs, a drip irrigation system was installed and Peng formulated a fertigation recipe. “We explained the costs and estimated pay back period. Then we installed a Hoogendoorn climate computer and connected everything we can control such as the window vents and the pad and fan cooling system.”
The seedlings, varieties Fortesa 74-112 (cherry tomato), Rijk Zwaan 882 (medium size) were planted 1 Jan 2016 and they haven’t used any chemical products yet. Production still doesn’t compare with Dutch houses but it is much better than solar greenhouses. If production continues as expected, they should be able to achieve 25 kg/m2 from January to early August. A normal yield in China is just under 9 kg/m2.
The greenhouses are 4.8 metres high but there is still no rail system for trollies. It’s almost impossible to work at the top of the plants, says Peng frustrated. Workers stand on a table and then move the table to work on the next plant. “However, we were able to convince them to use bumblebees for pollination, instead of vibrators, and this is going very well. The tomatoes have a good shape and flavour.”

Pick-you-own tourism

The harvest is mainly for the group’s own five star hotel and restaurant but they also offer pick-your-own for residents living in the nearby towns. In fact, it’s gaining a reputation as a tourist attraction and many people come and pick the tomatoes because they know it is safe product.
“People like the experience of visiting a greenhouse and they pay double the normal price for tomatoes. However, it is not ideal in terms of hygiene and it does pose a disease risk. I am trying to persuade the owners to harvest the tomatoes themselves and perhaps sell them in their eco-restaurant which is very nearby,” she says.

Further expansion

Blue Horizon has already asked the consultant to help design and advise on the operations of a new 6-10 hectare greenhouse they hope to build soon. The company’s four other greenhouses could also be reconstructed in future. “I’ve also just done a reconstruction design for a greenhouse in Changzhou.” It currently produces pot plants but it wants to switch to 5,000 m2 for tomatoes and 2,000 m2 for strawberries. “This investor is looking for benefits so we did a lot of calculations to show the potential profit. It is a trend and we are being asked more and more for this service,” says Peng.

Demo centre

In a similar way a demonstration centre at Chongming Island, Shanghai, is aiming to integrate technology and skills into Chinese horticulture.
The National Engineering Research Centre for Protected Agriculture (NERCPA) is a two hectare demonstration unit designed by Dutch greenhouse manufacturer, the Bom Group, and built by its Chinese partner, Dushi Green. Priva coordinated the state-of the-art project which includes underground storage for heating and cooling storage, irrigation and internal transport systems. It contains trial compartments of 1,000 m2 which is similar to the Delphy Improvement Centre in Bleiswijk. The aim of NERCPA is to verify the possibilities for new technology in the Chinese market as well as offer training.
When clients are considering investing in a greenhouse in China they tend to visit NERCPA first, says Peng, whose colleague Didi Qian, was involved in setting up the centre. “Often in China people build a greenhouse and then seek cultivation advise but often the greenhouse is not suitable for the crop they want to grow. Now they are starting to realize that they first need a clear idea about what they want to grow and then should build a special greenhouse for those crops.”


Many high tech greenhouses in China are failing to fulfil their potential due to lack of knowledge and technical expertise. Some of these nurseries are reinvesting and by accepting expert advice have significantly improved yield and efficiency.

Text: Helen Armstrong. Images: Blue Horizon