This project's research activities officially ended in March 2021. Legacy in SmartAgriHubs Portal

City farming for leafy vegetables


Sjoerd Kessels


Ellis Janssen-van Boxtel
Niels Vlasblom

City farming for leafy vegetables

Implementing value chain innovation for leafy vegetables in convenience foods by integrated indoor climate control and logistics.


Eternal spring is what this use case’s location in the Netherlands offers. If you know the Dutch weather, you are probably furrowing your brow right now. So, let us explain! A sunny and warm day in spring are roughly the conditions the team simulates in their indoor farming facility at the High-Tech Campus in Eindhoven as part of their contribution to food security in the future, especially for the urban population. Due to the absence of natural sunlight, the quality of any indoor crop depends on the perfect symbiosis of all factors such as climate control, lighting, sensors, software controls and logistics. After an initial degustation, we can confirm that Sjoerd Kessels, the Use Case Coordinator, and his team of plant and data specialists are already close to the perfect growth recipe for a variety of crops.

Technological setup of an indoor farm

After its recent renovation, the GrowWise Research Center is the largest facility of its kind with 234 m² and 8 climate control rooms, 6 multi-layer cells, 1 dedicated high wire cell, and 1 multi-layer strawberry setup, each equipped with Philips GreenPower lighting with blue, red, white and far-red LEDs.

This multi-layer system gives them the chance to experiment with different dynamic light recipes for the same crop. This arrangement was previously impossible because the traditional high-pressure sodium (HPS) lamps and fluorescent tubes as well created too much heat for a multi-layer setup. The LED lighting is a developing technology that is continuously breaking new ground and provides a unique spectrum of light.

To create the best environment for high quality herbs, fruits or vegetables, the team also monitors the ideal temperature, CO2 levels, humidity, best substrates and required irrigation through the integrated system. While irrigation is undoubtedly a key factor, atmospheric CO2 is equally important as any plant’s metabolism produces sugar (glucose) during photosynthesis. Since every characteristic is optimised, the results range from prolonged shelf-life, enhanced taste, higher yield and stronger plants to increased level of nutrients and vitamins.


Productivity (kg crop harvested per m² per year)


Waste of harvested products


Pesticide use

One of their eight climate rooms is dedicated to our use case: leafy vegetables, or lettuce to be precise. Thanks to LEDs it is now roughly only twice as expensive to grow lettuce in an indoor farm compared to open field agriculture. The harvest per square meter per year on the other hand, speaks for itself. While open field agriculture (in the Netherlands) produces on average between 20-30 kg, greenhouse farming with artificial light raises it to 75 kg. An indoor farm, however, reaches up to 100 kg per square meter per year.

In terms of sustainability, the fresh produce moves closer to the consumer, who gets consistently great quality all year round without any applied pesticides or other agrochemicals. There is no pressure of diseases at all due to the constant circulation and conditioning of air within a closed ventilation system. Furthermore, it alleviates the pressure on the supply chain and the effects logistics have on the climate while saving 90% of water which usually simply evaporates in open field agriculture. Lastly, the waste percentage is extremely low because the entire plant is used and no leaves removed.

Dynamic lighting for different growth phases

The GrowWise Control System enables dynamic lighting through which the spectrum and intensity can be adjusted in the different growth phases. For instance, red lettuce requires a particular adjustment to turn red. If this is done to early, however, it will inhibit growth.

Currently there are about 1000 different varieties of lettuce alone and this is only one example of the specific requirement each crop has, which makes extensive data collection paramount to determine the best growth recipes. Thus, making precise information derived from different growth recipe experiments on each layer in the climate room a key factor. For instance, too much far-red light negatively affects the quality, while too much blue light inhibits the growth stretching (elongation).

A grower’s success also depends on a uniform setup. Only then can the plant specialists of this use case assure that their growth recipe is applied with precision. Sensor nodes are crucial in these regards to monitor exactly if their recommendations correspond with the parameters in the room. It also gives the team the chance to initiate countermeasures at an early stage. A fail-safe so to speak, to inherently respond in a way that causes minimal or no harm to the equipment or produce. To achieve the best results, however, a collaboration with technicians and physicists is required to triangulate the growth setup with fundamental research, algorithms as well as economics.

Scalable growing solutions

There is a remarkable thing happening when leaving an indoor farm with LED lighting. Everything looks green! This effect occurs because the human eye is very sensitive for green light which is depending of the used light recipe without white/green in the climate room.

When leaving the room, we return to a balanced visible light spectrum which includes all the colours of the rainbow. Suddenly there is an abundance of green light available, which was previously missing. Hence, our eyes need to adopt for a minute to the balanced spectrum of regular light. Luckily, this only takes a minute!

While the room we had just left has 180µmol/s/m2, the GrowWise Control System  is able to control up to 350µmol/s/m2. The team offers their customers a variety of full-service options for differing crops: from small, simple climate rooms with lettuce to sophisticated, giant commercial applications growing multiple crops, herbs, tomatoes and soft fruits. One thing most of them have in common is the GrowWise Control System which can be considered the lighting brain of every indoor farm. And much like the human brain, the system can adapt to the customer’s needs. Another thing the produce of this indoor farm has in common is the cleanliness of the end-product. The produce is free of any agrochemicals so by washing it, as requested by some countries’ legislation, you end up making it dirtier.

In the introduction we mentioned that this use case is contributing to food security in the future. And their endeavour does not end here as they currently have other trials going on with strawberries, tomatoes, herbs or cucumbers. Basically, anything can be grown indoor if it is economically viable and environmentally sustainable.

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Achievements, products & services

Sensors to provide process feedback

Colour controllable and dimmable LED lighting

Deep understanding of crop growth and crop selection

Tightly matched climate management

Ensuring optimal growing conditions through hydroponic irrigation

Ideal spacing strategies to optimise growth

A single control system to manage operations and track data

Use case partners

IOT Catalogue


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