Cucumber production under LED lighting presents growers with a unique set of challenges -and opportunities. In a trial conducted at Delphy Improvement Centre, Sollum Technologies explored how dynamic lighting strategies, including far-red (FR) modulation and blue supplemental morning lighting (B-SML), could impact crop balance, yield, and energy use.
This collaboration reflects Sollum's mission to deliver dynamic lighting solutions that adapt to each crop, helping growers meet production goals with greater precision, consistency, and efficiency.
Cucumber is a highly light-sensitive crop that reacts strongly to the spectral composition of its growing environment. When transitioning from HPS to LEDs, growers often face challenges such as leaf curling and reduced fitness in the absence of far-red (FR) light, fruit abortion and imbalance following spectral changes, and cultivar-specific sensitivity to lighting strategies.
The trial focused on identifying how dynamic far-red (FR) management and blue supplemental LED (B-SML) applications could preserve plant balance and reduce energy consumption, optimize performance for different cucumber varieties, and improve physiological readiness at the start of the day.
Trial design and lighting strategy
The trial was conducted at the Delphy Improvement Centre, focusing on the Long English Cucumber crop. Two varieties were tested: Uptrace, intended for the Dutch market, and Hi Lumiere, aimed at the North American market. The planting density was set at 2.5 stems per square meter, with a photoperiod of 18 hours. The trial utilized a photosynthetic photon flux density (PPFD) of 250–270 µmol/m²/s, provided by Sollum's SF-ONE™ lighting system, over a harvest period of 13 weeks.
Dynamic FR strategy
The trial began with 9% FR, which was gradually reduced to 7% and then 6% throughout the photoperiod. During one week in December, FR was completely removed from 9 a.m. to 4 p.m.—resulting in visible leaf curling and lower plant vigour. Two to three weeks later, fruit abortion appeared, particularly in the lower trusses.
The impact was clear, FR is critical during the darkest periods of the year to maintain cucumber plant health and productivity.
Key results
Hi Lumiere showed stronger overall performance and Light Use Efficiency (LUE) throughout the crop cycle. Uptrace was more sensitive to FR withdrawal, displaying earlier signs of curling and fruit loss.
These differences reinforce the importance of variety-specific lighting strategies under LEDs.
B-SML: A physiological trigger
In a separate protocol, researchers applied 2 hours of 100% blue light treatment (10 µmol) in the early morning before the main photoperiod.
This treatment improved photosystem II efficiency (PhiPSII) and influenced stomatal conductance, suggesting an increase in physiological readiness for the day.
While yield gains were not immediately evident, the data supports further investigation into B-SML as a tool for enhancing daily plant performance.
Conclusions and takeaways
This trial confirms that cucumbers can thrive under dynamic LED lighting, with strong performance potential when lighting strategies are aligned with the cultivar's unique needs.
FR is essential during low natural light periods to prevent curling and imbalance.
Dynamic spectrum adjustments can improve energy efficiency by dialing FR up or down depending on ambient conditions.
Cultivar-specific light strategies are not optional—they are critical to achieving optimal outcomes.
Introducing B-SML at the beginning of the photoperiod is a promising strategy for supporting plant physiology after sunrise-like lighting condition. In summary, B-SML is the most effective in promoting the stomatal opening of the leaves before sunrise, so that plants can absorb sufficient CO2 and photosynthesize immediately after exposure to higher light intensity.
Thought its dynamic LED solution and crop-specific expertise, Sollum continues to support growers with dynamic LED lighting that responds to the realities of greenhouse cultivation.
This cucumber trial further strengthens the collaboration between Delphy and Sollum Technologies, following the positive results achieved in our pepper production trial published in January 2025. Together, these studies highlight the flexibility of dynamic LED lighting strategies and their ability to drive measurable outcomes across different crops.
For more information:
Sollum Technologies
sollumtechnologies.com