Unlocking the Potential of Greenhouses with Light

Since the 1800s, light has been a fundamental part of the greenhouse value chain, with sunlight being the main constant in growing everything from food to flowers. As the industry has evolved and controlled environment horticulture has grown, researchers and growers have joined forces to identify the best seed stock, the right nutrients and the most effective pesticides to increase both the volume and quality of greenhouse harvests. Yet our approach to light hasn’t evolved in line with these other inputs and greenhouse growers now have an opportunity to unlock new value in their commercial operations by looking at light through a different lens.

According to analysts at QY Research, “The global Commercial Greenhouse market was valued at 29,600 million US$ in 2018 and will reach 57,300 million US$ by the end of 2025, growing at a CAGR of 8.6% during 2019-2025.”* This predicted 94% increase in market value in just seven years reflects both the opportunity and the imperative that growers now face; with the global population set to top 9.7 billion people by 2050, producers must find new methods to increase food supplies using the finite resources that are available.

However, these targets and challenges aren’t necessarily as insurmountable as the headlines may lead us to believe. The balance of power in horticulture between art and science is shifting as global researchers unlock more secrets of plant biology, increasing their understanding of how plants develop from seed through to maturity. Growers can now take these insights, combined with accelerating technological advances and evolve their operations to become leaner, more productive and sustainable.

Light: the new precision tool of greenhouse growers

It could be argued that until recently, light was seen as a fairly blunt instrument in the grower’s toolkit. The two primary aspects that could be manipulated were the amount and intensity of light reaching the plant. Aside from relying on the sun, growers could use traditional high-pressure sodium (HPS), compact fluorescents (CFLs) or metal halide lamps to extend the length of the growing day (photoperiod) as well as the intensity of light delivered. HPS lamps deliver a warmer coloured white light, as well as infrared radiation, whereas CFLs and metal halide lamps tend to deliver a cooler, white spectrum light. However, these lighting solutions are typically energy-hungry and, particularly in the case of HPS, can also generate a lot of wasted heat. Although this can be useful in greenhouses located at high latitudes and in colder climates, it also adds a new variable that greenhouse operators have to manage in order to create the perfect growing conditions for their chosen crop.

Today, far more is known about the light spectrum and the precise impact of different light wavelengths on plant morphology. Light has a crucial impact not only on plant shape and size, but also on elements like taste, nutrition and colour. The development of LED technology by companies like GE Current, a Daintree company, has enabled the use of bespoke LED solutions that harness this scientific insight and deliver a tailored lighting recipe depending on the needs of the plant.

Light quality is a factor in the biosynthesis, metabolism and accumulation of phytochemicals. By providing a specific light spectrum in addition to controlling the photoperiod, growers can optimise the production of phytochemicals (via plant photomorphogenesis), which govern elements such as taste, nutritional content, aroma and others important characteristics such as the shelf life of fresh produce.

Hans Spalholz is a plant scientist who has spent his career understanding the impact of different light wavelengths on plant morphology. He is now helping Current to develop and refine its specialist range of horticulture LED solutions to help indoor farmers achieve high-quality, commercially viable yields. He notes, “Even though modern greenhouses have been around for decades, we are now just scratching the surface of their potential.”

Harnessing complexity for success

As plant science reveals more and more insights into how plants react to the basic inputs of CO2, water, nutrients and light at different stages of growth, the ways in which greenhouses produce food, flowers or even plants for medicinal use such as cannabis, can be refined to drive higher yields than ever before.

“By understanding the exact role of different light wavelengths on different biological processes in a particular plant cultivar, we have far greater control over what the end product looks like, simply by giving the plant the exact blend of raw materials and light needed at that precise stage of growth,” explains Spalholz. However, with this knowledge comes the realisation that greenhouse cultivation has the potential to be infinitely more complex as the ability to fine-tune each variable becomes possible at every step and individual factors such as geography, climate and customer trends are identified and considered.

Such a realisation can be daunting but established growers can’t afford to ignore its potential as new market entrants adopt the latest technology and techniques to compete on a global stage. For this reason, the success of future greenhouse operations will truly become a team effort with growers working closely with their technology partners and plant scientists to understand their individual circumstances and design the most effective operation to optimise commercial production.

What does “success” look like?

When we think about “optimising commercial production”, it’s common to fall into the “bigger, faster, more” mindset, but for some greenhouse producers, the “best” harvest may look completely different from others. For example, Current worked with a producer of lettuce in a warm, sunny climate who found that each head was growing too large and open to fit into the commercial packaging. The client wanted to produce more dense, compact heads of lettuce which were more attractive to local consumers. The team deployed Current’s Arize horticulture LEDs with an alternative lighting recipe that incorporated more blue wavelengths to encourage the lettuces to grow in a way that satisfied local requirements.

If every greenhouse operation is different (due to factors such as geographical location, climate, scale, type and age of physical structure, etc.) and the way in which every plant species (even down to the precise cultivar within that species) responds to different light wavelengths is individual, the trusted relationship between a grower and their partners becomes even more crucial.

“First and foremost, it’s my job to listen,” says Hans Spalholz. “Every grower has different challenges and wants to achieve different results according to their individual markets, customer demand and operational capabilities. So, we have a conversation where we work out the balance between commercial production needs and the specific plant biology in question. I can then advise on the most appropriate lighting recipe to help them achieve their specific goals.” Such conversations can also incorporate troubleshooting and more general advice to help optimise production. For example, plant spacing within the facility to avoid shadowing, temperature, humidity and nutrition all play a role in ensuring the most successful harvest alongside the perfect light recipe.

Switching from more traditional lighting to a tailored LED recipe can feel like a risky step to producers who have mature operations with predictable plant growth and financial returns. However, as energy prices and the need to operate more sustainably increase, and as new competitors gain an advantage through advanced technology, the long-term benefits become irrefutable. For growers looking to explore this important step, Current’s team works closely with them to trial and demonstrate the technology against their individual criteria, selecting the most appropriate LED solutions and light recipes for their needs.

Lighting the path to future growth

Although the advances in our understanding of LED lighting and its impact on plant morphology have allowed us to start using it as a more powerful tool in recent years, the future for indoor farming using tailored light wavelengths to their fullest potential is just around the corner. Few growers today feel comfortable with the idea of manually tuning a light recipe and risking an unpredictable result so for now, broad recipes have been developed to elicit a predictable response from a wide range of plants.

In 2050 and beyond however, greenhouses will use a host of connected sensors and sophisticated artificial intelligence to conduct real-time, in-depth analysis and management of each individual plant within the facility. These smart greenhouses could potentially feature automated, tuneable LED lighting that delivers the precise spectrum required by the individual plant cultivar as it grows, to maximise yields and return on investment. As we start a new decade with the effects of climate change already starting to bite, the race to secure the future of our food supplies is already underway. Light could be one of the most powerful tools available to feed our future global population, tapping into plants’ natural genetics to grow healthy, tasty, appealing produce in a way that won’t cost the Earth.


*Global Commercial Greenhouse Market Professional Survey Report 2019

For a more in-depth technical overview of the impact of light on plant growth, check out our latest whitepaper: LED Grow Lighting101: A Guide to Greater Yields, More Harvests and Higher Profits