Home Posts Tagged "hydroponics"


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Christ en Jacqueline Monden of De Kruidenaer in Etten-Leur had hybrid lighting installed in their new high-tech greenhouse, in which they grow basil, just over a year ago. Until now, their experiences have only been positive: a higher production yield, better quality, a longer lifespan and improved plant resilience.

Last year, Christ Monden had a new 14,000 m2 greenhouse built with diffuse glazing, a humidifier and hybrid lighting for the cultivation of basil on water (hydroponics). The basil is grown in six 2,100 m2 containers, which Christ refers to as ‘ponds’. The young plants are started in this greenhouse as well. They are transplanted to ‘floaters’ with plant holes after 1 to 2 weeks. The ponds are located parallel to one another, without any aisles in between. As a result, optimum use is made of the available space.

Short cultivation cycle

On one side of the greenhouse, the floaters with the young plants are set to drift in the water and – after 3½ to 5 weeks – they are lifted out at the other side of the greenhouse for harvesting. This is a short cultivation cycle, thanks to the intensive lighting, which ensures a constant supply of fresh basil six days a week. In addition to basil, the Brabant-based nursery also grows 23 other types of herbs, lettuce (grown hydroponically) and sweet peppers (amounting to a total of 8.5 hectares of greenhouse cultivation and 23 hectares of open-field cultivation with tunnels) for the retail, food service and export industries.

Basil likes warmth, but not too much. In this case, LED lighting is the ideal solution.

Chequerboard pattern

In addition to diffuse daylight, the plants also receive artificial light provided by Oreon Grow Light (260 KVA) LED fixtures, in combination with Gavita SON-T (460 KVA) lighting, with a maximum output of 100 μmol/s (the output of the LED system alone is 50 μmol/s). The light fixtures are suspended above the crop in a chequerboard pattern. Their design (lighting plan) and the installation of the system were carried out by Voshol Warmte-Elektrotechniek. Oreon LED fixtures have been installed, among others, at lettuce grower Boer den Hoedt and Koppert Cress.

Water cooling

One of the unique features of the Oreon LED fixtures is its water cooling system. This has various advantages according to Jos Duijvesteijn of Voshol. ‘Basil likes warmth, but not too much. In this case, LED lighting is the ideal solution LED is composed of diodes, which get very hot at the back. Heat is, of course, detrimental to the useful life of electronic devices. Thanks to the cooling system, we can keep the temperature of the lamp between 35 and 45 degrees Celsius, thus substantially extending their useful life (L90 = 35,000 hours, ed.). The heat discharged through this process (50 degrees Celsius) is reused by De Kruidenaer – for heating the ponds, for example. This means that no energy is lost.’

The heat discharged through this process is reused – for heating the ponds, for example.

Test set-up

Christ explains why he chose to install the Oreon LED fixtures: ‘They came out best in a test that was conducted prior to the construction of the greenhouse. The plants grew very uniformly and were super strong. In the end, we opted for 50% SON-T and 50% LED because basil can really use this extra heat. We can light the plants exclusively with SON-T, or exclusively with LED, or with both types of lighting. Thanks to the LED fixtures we can give the plants light for much longer, both in the morning and in the evening, particularly at this time of the year.’

Prolonged cultivation

The lighting is switched on as frequently as possible, up to a maximum of 20 hours per day. ‘Last year, I used more SON-T lighting than I had expected. The crop was able to tolerate the extra heat very well. We use SON-T exclusively or in combination with LED, but have not used exclusively LED all that often yet.’ Christ thinks that the LED fixtures were switched on for 2,000 hours last year. Thanks to the LEDs he can give his plants prolonged light and start earlier in the season – four to six weeks each season, he estimates.

We were able to produce the anticipated volumes, and the quality is better. The plants also have a longer lifespan.

Longer lifespan

The result after growing plants under hybrid lighting for one year is positive. We were able to produce the anticipated volumes, and the quality is better, says Christ. Additionally, judging from customer response, Christ noted that the plants have a longer lifespan. He also has to purchase less product in addition to what he grows in order to meet customer demand. ‘They prefer basil grown in the Netherlands, with a PlanetProof Hallmark (previously Milieukeur). We were able to get through last summer – with temperatures above 35 degrees Celsius – much better than I had anticipated.’


Christ is convinced that the LED lighting contributes to improved plant resilience: ‘During the tests, we noted stronger plans, with sturdier leaves and shorter internodes. The colour was better, too. I am sure that this gives the basil has greater vigour. These results are also reflected in our crops. Basil is a highly demanding crop, a real “prima donna”. Things can be completely different from one day to the next.’

I am convinced that the LED lighting contributes to improved plant resilience.


Although the investment in a new greenhouse ended up being much greater due to the purchase of the LED lighting fixtures, Christ and Jacqueline Monden are very satisfied about the results. ‘We grow almost all the basil ourselves, particularly in the season. What I am most satisfied about is the quality of the crop. We aim to grow the best basil in Europe. In about five years’ time we want to stop growing sweet peppers entirely. It has been going really well until now,’ he says with a wink that shows his marvellous feeling for understatement.

More output

For which types of growers is hybrid lighting interesting? ‘The product range is becoming increasingly broad,’ says Jos Duijvesteijn of Voshol. ‘There are plenty of possibilities in the cultivation of herbs, particularly if heat is a problem. The same goes for growing lettuce. Hybrid lighting is really on the rise among tomato growers. We are currently rolling out the first projects, with LED top lighting in combination with SON-T. A gigantic advantage is that the LEDs will give you a much greater output, with a smaller capacity. This means that you can get more micromoles from the same capacity.

Light patterns

We are very enthusiastic about Oreon’s water-cooled fixtures. This product is stable, and has pretty much be reached the highest level in terms of engineering. Also, once it has been installed there is nothing you need to do. You can also generate a diversity of light patterns with LEDs, for the vegetative and generative growth of the crop. The latter still requires a lot of research, but I can certainly identify opportunities here.’

This article was written in collaboration with De Kruidenaer, Voshol Warmte-Elektrotechniek and Oreon. Text and photos: Mario Bentvelsen. Video: BrokxMedia.

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Apart from Vertical Farming, there are numerous hybrid cultivation initiatives taking place in and on buildings, also known as Urban Farming and Rooftop Farming. Even restaurants, supermarkets and offices are experimenting with growing fruit and vegetables in cities.

Vertical Farming is, of course, not suitable for crops that grow in an upwards direction, such as tomatoes and cucumbers. This problem was solved in Jackson (Wyoming) with the construction of an impressive building incorporating huge amounts of glass, designed by Larssen Ltd.: a very expensive building costing 3.7 million dollars, partly due to its earthquake-proof construction. Three stories of the building are dedicated to LED-illuminated Vertical Farming, with two stories reserved for herbs and leafy vegetables and the third for tomatoes. The 3,800 m2 surface area is sufficient for a production of 45,000 kg a year. The building is intended to bridge the awareness gap between horticulture and the city’s inhabitants and also provides space for education. The vegetables can be seen growing from behind a glass wall. The project received financial support through crowdfunding and the municipality is the owner of the building.

Restaurants and supermarkets

InFarm is directed at growing vegetables in big cities; in and by restaurants and the retail industry. ‘We are the new farmers and the city is our company.’ In his mind’s eye, the founder of InFarm is seeing supermarkets with multi-tier cultivation for leafy vegetables above the shelves. You simply can’t buy fresher food with fewer food miles than this! InFarm developed the Kräutergarten for the Berlin-based Metro wholesaler, just as Mirai did in Japan: a multi-tier LED-illuminated greenhouse in the supermarket. The crops grown consists primarily of herbs (basil in particular) and leafy vegetables grown on a shallow layer of water (hydroponics).

You simply can’t buy fresher food with fewer food miles than this!

InFarm also operates the UFcontainerfarm in Berlin: a container with a small greenhouse on top. Tilapia fish are bred in the container. The water from the fish is pumped up to the greenhouse, where it is used to water the plants after it has been purified. This concept is also used in London, where it is called a GrowUp Box.

Above and below ground

An outsider in Urban Farming is SkyGreens. This Singapore-based initiative grows vegetables on trays suspended in gutters. These gutters circulate vertically by means of two A-shaped pillars nine metres tall. The circulatory movement enables each plant to obtain the same amount of sunlight. The company has 1,000 of these vertical towers with 20 gutters each and produces 800 kg of vegetables a day, including Chinese cabbage, spinach and other leafy vegetables.

The London-based Farmdrop initiative produces herbs underground, in former bomb shelters.

Another outsider, but of an entirely different calibre, is the Pasona office building in Tokyo, where a myriad of plants and vegetables are grown on and in the building, which also features a dedicated Vertical Farming division. The vegetables grown here are intended for the company restaurant. In conference rooms, workspaces - in fact, all over the building - you will see tomatoes growing all the way up to the ceiling, or sweet peppers and eggplants, broccoli, lemons and even passion fruit. A total of 200 varieties of vegetables, fruit and even rice are grown here! The staff is free to pick whatever they want. The company employs a permanent staff of ten people to keep the vegetables in tip-top condition. Not everything is grown efficiently, but the project was never intended to achieve a high production rate; the concept was developed to engender awareness for food provision.

The London-based Farmdrop initiative produces herbs underground, in former bomb shelters: 30 metres below the surface. It took Farmdrop two years to conquer all the challenges of underground cultivation.

Rooftop greenhouse

Where Vertical Farming appears to be booming, there is less interest among the inhabitants of big cities for rooftop cultivation - in greenhouses, at any rate. Few people practice greenhouse horticulture on rooftops, but when it is, this is mainly in the USA.

According to GothamGreens, urban farming is all about re-establishing the connection between people and the food they eat, educating young people and nurturing the soul.

A firm called GothamGreens operates a series of rooftop greenhouses, in which leafy vegetables are grown in gutters, in New York and Chicago. The first 1400 m2 rooftop greenhouse was built in 2011, and the total surface area of GothamGreens has since risen to 16,000 m2 distributed across four sites. The biggest measures 7,000 m2 and is built on the roof of a bowling alley. According to GothamGreens, urban farming is all about re-establishing the connection between people and the food they eat, about educating young people and nurturing the soul. ‘Urban Farming will never become a primary source of food, but its impact is lasting.’ A head of lettuce grown here costs around $4 at Whole Foods, almost twice as much as conventional lettuce grown in the field and $1 more than organic lettuce.

Bright Farms also aimed to dedicate itself to rooftop cultivation, but it was forced to give up its plans due to the difficulties it encountered with permit applications and the costs, which were 20% higher in comparison to an 8.5 million dollar greenhouse built just outside of the city.

The Hague

The Swiss Urban Farms initiative in Basel built a 250 m2 rooftop greenhouse as a pilot in 2013. Three years later, in May 2016, the UF De Schilde rooftop greenhouse opened its doors in The Hague, the Netherlands. As opposed to the rooftop greenhouses in the USA, which are all on one or two-storey buildings, this greenhouse is situated on top of building six storeys tall. Greenhouse builder Van der Valk Kleijn designed an extra-sturdy greenhouse with double glazing incorporated into the walls and roof. The project’s financiers are SVn (Stimulation Fund for Public Housing) and private investors. The greenhouse collaborates with Rijk Zwaan, Koppert Biological Systems and Priva.

UF hopes to cater to 900 families who can order fresh fish and vegetables via a subscription, as well as to restaurants.

The 1,200 m2 greenhouse is the biggest rooftop greenhouse in Europe. The farm grows lettuce, micro-greens and tomatoes. The floor underneath the greenhouse is rented from the municipality of The Hague to farm fish, whose waste products are subsequently used as nutrients for the plants. Visitors can watch the cultivation process from behind a glass wall. UF hopes to cater to 900 families who can order fresh fish and vegetables via a subscription, as well as to restaurants: 500 tilapia fish a week and 50 tons of vegetables a year. UF expects the venture to be a success, mainly because consumers are enthusiastic about initiatives engaged in the local production of food.

Priva developed the necessary control technology for the project, which required an extraordinary degree of innovation taking into account all the regulations that apply to fish farming (e.g. temperature and oxygen content) and irrigation (including fertilising, temperature and electrical conductivity) for the various greenhouse sections in which lettuce, tomatoes and leafy vegetables are grown. On top of that, Priva also developed the systems for CO2 and climate control.


Lufa Farms in operates a 3,000 m2 rooftop greenhouse in Montreal (Canada) and one in Laval measuring 4,000 m2. Both were built by the Montoni Group and Kubo. The greenhouses are capable of withstanding large amounts of snow.

Verticrop combines a rooftop greenhouse with Vertical Farming, with cultivation on horizontally circulating plates in twelve tiers in a greenhouse on top of a parking garage in Vancouver (Canada). As the plates rotate slowly, all plants obtain the same amount of light and are watered and harvested at a particular point. However, the company has since gone bankrupt. The investment in both the rooftop greenhouse and a complete new cultivation system was probably too high. Additionally, crops grown using this system tend not to grow as profusely due to the limited amount of daylight they receive.

Horticulture 3.0?

An interesting point for consideration is the extent to which the higher costs of a rooftop greenhouse are balanced against the presumed higher quality, freshness and local distribution. Or will the multi-tier cultivation of fruit, vegetables and fish under fully controlled conditions pave the way for Horticulture 3.0, with its smaller CO2 footprint, retention of local employment and higher diversity in supply as its social driving forces? In the meantime, restaurants, supermarkets and offices are all experimenting with growing their own vegetables, and urban consumers have discovered the art of growing their own food as a meaningful and pleasurable pastime.

Locally grown, super-fresh and demonstrably sustainable could very well become the new standard of reference.

The consequences are, however, very limited for the Dutch horticulture industry, which has traditionally always focused on the export of primarily herbs and leafy vegetables to other European countries. This does not detract from the fact that the industry should consider expanding its focus area to feeding mega-cities rather than ‘shifting around’ products from one location to another, as the CEO of Hoogendoorn, Martin van Gogh, recently suggested during the Greenport Annual Event. Locally grown, super-fresh and demonstrably sustainable could very well become the new standard of reference.

Text: Tuinbouwteksten.nl/Theo Brakeboer. Photo: UrbanFarmers/Martijn Zegwaard.

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A lot of hard work is currently being done in The Hague on the topmost storey of a former Philips factory building, where a modern urban farm covering 1,900 m2 is being built. A greenhouse is being constructed here, as well as an indoor fish farm. With investments totalling 2.6 million euros, UF De Schilde is everything but a hobby project.

The Swiss Urban Farmers, a spin-off that has its origins in the ZHAW University in Zurich, was launched in 2013 with the development of De Schilde, in collaboration with the Municipality of The Hague and various horticulture specialists including Priva, Koppert and Rijk Zwaan. As from 20 May, private individuals, retailers and restaurants will be able to buy ‘exclusively grown’ vegetables from this urban farm, such as tomatoes, lettuce and herbs, as well as tilapia fish. If it were up to the Municipality, the rest of the building - which is largely vacant - will house even more initiatives that will put The Hague on the world map as a centre of urban farming.

Fast start

Mark Durno, the director of Urban Farmers Benelux, is pleased with the fast start. ‘We are working on a similar project in Switzerland, but the Swiss authorities require you to submit your plans to a vast number of different agencies. This translates into having to file fourteen different versions of 250 pages each, all of which are examined individually. In The Hague a preliminary version was sufficient, and it took only one meeting to discuss the construction and environmental permits with the authorities.’

It’s now up to Durno to staff the farm with people who not only understand how to grow vegetables, but also how to farm fish. ‘They have to be open to new technologies and be creative. This is not a traditional farm.’ He has received a remarkable number of responses from people yearning for a career switch. ‘We’ve received letters from accountants who wants to become urban farmers, for example. Of course we think that’s fabulous, but let’s not forget that we are running a commercial farm here!’

Visit the Urban Farmers website for more information.

Source: Financieel Dagblad. Photo: Urban Farmers.

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This is the fourth time in a row that trial station Proeftuin Zwaagdijk successfully concluded a trial investigating the hydroponic culture of chrysanthemums. No plants were lost during the trial, which was held from October to November 2015. The average branch weight - in the most favourable cases - was 82 grams for the ‘Bacardi’ variety and 96 grams for ‘Alero’ chrysanthemums.

The leaves as well as the roots were of an outstanding quality. This was also the case for plants grown for the fourth time in rows in which neither the nutrient solution was replenished nor disinfection had taken place. The plants suffered only minute pressure from thrips. Possible improvements could be achieved primarily in the area of crop uniformity.

Just as in the previous trials, the cuttings had been rooted in glued coco plugs and transferred to Botman Hydroponics floaters directly after, where they were kept floating on a 30 cm deep nutrient solution that was continually aerated and kept in circulation. The trial investigated the effects of water temperature and the addition of micro copper to the nutrient solution. ‘Bacardi’ and ‘Alero’ clearly reacted differently to the treatments provided.

Sustainable cultivation system

The underlying objective for these trials is the development of a sustainable cultivation system. The system, which is separated from the subsoil, will lead to considerable reductions in the emission of nutrients and chemical pesticides.

The following parties were involved in the trials: Fred van Paassen, Green Simplicity, Bovebo, Dekker Chrysanten, Fides by Dümmen Orange, Botman Hydroponics BV, KaRo BV, van Iperen and the Allsmeer Chamber of Commerce/Greenport Innovation Engine.

Source/photo: Proeftuin Zwaagdijk.