Your recipe for growth

Most commercial greenhouses are growing vegetables on vertical high-wires these days, and the demand for artificial lighting has been increasing for years. To help greenhouse growers grow their crops even more efficiently, Philips lighting is always searching for the most effective solution. Ten years ago, we introduced a new type of lighting called interlighting, followed recently by a high-output version. By now, this way of applying light to plants has proved itself numerous times, and we’d like to share what we’ve learned along the way. 

Many high-wire crops like cucumbers and tomatoes are grown using traditional HPS (high pressure sodium) grow lights above the crop. But with the arrival of LED interlighting in 2008, Philips lighting began researching the effects of placing LED lighting within the canopy of high-wire plants to improve crop yield and quality. These trials showed that placing LED interlighting within the canopy of high-wire plants allows you to focus growth-stimulating light on parts of the crop that are normally darker, so that the leaves have an even greater impact on fruit production. This can significantly improve the quality and yields of crops.

Back in 2010, Dutch tomato grower Jami and his growers' cooperative were closely involved in these trials, and the positive results convinced them that intercanopy lighting was the way to go. In 2012, growers cooperative Van Nature (where Jami is one of the members) invested in a Philips hybrid lighting system, combining HPS lights with a double line of LED interlighting which was installed in Jami's greenhouse. Their greenhouse was too low to accommodate sufficient HPS lighting to support year-round production. That meant that this hybrid lighting solution was the best option for them. At that time, it was a 'forced choice'. Ask them now, and based on their experience and results with LED, they wouldn't want anything else. 

Mid-September 2018, we began a new round of trials in our tomato demonstration greenhouse at the Delphy Improvement Centre. In this project, Merlice vine tomatoes from De Ruiter Seeds are cultivated under a combination of Philips high-pressure sodium (HPS) and Philips GreenPower LED grow lights. We try to prove that a hybrid lighting solution can give growers a flexible way to apply high light levels to the crop right through early spring, while still taking advantage of the radiant heat provided by HPS lights at colder times of the year. The goal is to harvest over 55 kg/m² at the end of week 18.

In a few years, indoor (vertical) farms have become popular for producing healthy food year-round in urban environments and harsh climates. Leafy greens and herbs are the most commonly grown crops, but growers are looking to expand to a much wider variety of vegetables and fruits. In our Philips GrowWise research Center, we have been running trials on strawberries for several years. Recently we took these trials to the next level. Our goal? Develop a reference design for growing strawberries indoor, find the optimal light recipe and the best performing varieties.

At the Philips GrowWise Research Center in Eindhoven, we research all growth parameters relevant to a crop: light is obviously essential, but factors such as climate, variety choice and substrate are equally important. The idea of growing strawberries indoors was not new to us. In fact, we have been growing strawberries without daylight for over five years already. Despite some disappointments and setbacks, the results and first business case calculations proved encouraging enough to further pursue the topic and build a reference design for growing strawberries.