Winter cucumber trial: lower energy costs with spectrum control

New winter trial results from Närpiö, Finland, show a promising opportunity for cucumber growers: by intelligently adjusting the LED light spectrum, growers can reduce energy use while maintaining crop performance. In the 2025–2026 winter season, three commercial cucumber growers worked with Signify to explore how spectrum steering can help manage energy costs without negatively affecting yield.

The trial focused on reducing the use of far-red light, one of the steerable channels in a color-controllable LED installation. Compared with conventional cultivation, the daily light integral of far-red light was reduced by 17–30%. In practice, this meant that far-red light was either dimmed, temporarily switched off, or replaced during certain periods with more energy-efficient red light.

The results were encouraging. Even with reduced far-red light, the crop maintained strong yield performance, and didn’t show any negative effect on leaf size, fruit number, or total yield. At the same time, the growers achieved average energy cost savings of around €5,000 per hectare over an eight-week monitoring period. The exact savings varied by grower and depended on how the spectrum strategy was implemented, but the trial clearly shows that intelligent spectrum control can create value in day-to-day greenhouse operations.

“The trial gave us a practical way to test how much flexibility we have in the spectrum without putting production at risk. Seeing that we could reduce far-red use while maintaining crop performance is valuable input for future winter strategies,” says Jesper Prinsen, Production Manager at Oy Johan Prinsén Ab.

Signify’s Philips GreenPower LED toplighting force fixtures enable precise control of different wavelength areas, with each spectrum managed as a separate channel. This gives growers the flexibility to tailor light intensity and spectrum to the needs of the crop and the business. Red light is the most energy-efficient wavelength, delivering the highest light output per unit of energy, while blue, white, and far-red light each play their own role in supporting plant development and practical greenhouse work.

Far-red light is especially relevant for crop morphology. It can encourage larger, flatter leaves and longer petioles, helping the canopy intercept light more effectively. However, this trial showed that far-red light does not always need to be maintained at the same level throughout the day or season. With the right control strategy, growers can use far-red more selectively and cost-effectively while still supporting healthy crop development.

“For us, the interesting part was the ability to steer the light more precisely according to the crop and the energy situation. It shows that spectrum control can become a practical tool for daily crop management, not just a technical feature,” says Mattis Nordström, Grower at M.Nordström Ab.

The study also highlighted an important next step: timing matters. In this trial, spectrum adjustments were scheduled at fixed moments of the day, based on the assumption that electricity prices would be highest during those periods. In reality, price fluctuations were less predictable. This shows the potential of moving from fixed lighting schedules to smarter, data-driven lighting decisions based on actual electricity prices, that can respond more precisely to changing energy market conditions.

That is where the upcoming GrowWise smart energy application shows strong potential. Signify is working on GrowWise smart energy with the aim of turning greenhouse LED lighting into a smart, flexible energy asset, using the crop’s ability to tolerate carefully managed light shifts as a kind of “plant battery.” The proposition is being developed along two routes: a smart energy plan that creates an optimized lighting schedule for tomorrow and the coming days based on day-ahead prices, grower targets, plant models, weather forecasts, and luminaire efficacy; and smart energy shift, which can adjust power and light intensity in real time based on spot prices, DLI, and the grower’s strategy.

Together, these developments point to a future in which lighting intelligence goes beyond simply switching lamps on or off. Instead, lighting becomes an active management tool that helps growers balance plant needs, energy efficiency, and business priorities with far greater precision.

“Energy prices are becoming harder to predict, so it is important to have more control over how and when we use light. This trial shows that smarter lighting decisions can help growers respond to changing conditions while still keeping the crop on track,” says Stefan Nordmyr, Owner of Träskböle Trädgård Ab.

For growers facing volatile energy prices, the message is clear: controllable LED lighting opens new possibilities to manage costs without losing sight of crop performance. The trial in Finland shows that spectrum steering can already deliver meaningful energy savings today. With smart applications such as GrowWise smart spectrum and the upcoming GrowWise smart energy, lighting intelligence is becoming an increasingly powerful tool to help growers improve efficiency, safeguard production, and prepare for a more dynamic energy future.