LED lighting has a positive effect on the production and quality of roses from the cultivar Prestige.

This study shows the past year at Dutch Dutch Zuurbier & Co Rose Nurseries. The company was satisfied with the results, because the production was considerably higher than with the use of  SON-T (sodium lamps).

Especially in winter months

The recently published final report concludes that growing roses in LED lighting between January and March results in a higher yield per mole PAR, both in number of branches as in weight. After this period, the difference decreases due to the increased natural light.

Exposure to LED lighting had a stimulating effect on weight and no effect on number. The branch weight was the highest with SON-T + LED lighting.

Photosynthesis Measurements
The increased production in this experiment may partly be explained by a higher leaf photosynthesis. More extensive measurements showed that leaf photosynthesis in the cultivar Prestige peaks between 625 nm and 660 nm red light, and plants grown under LED lighting achieve a higher photosynthetic efficiency between 550 nm and 66 nm.

The lower crop temperature due to LED lighting required an additional heating duct above the crop to prevent moisture on the leaves.

Four treatments 

In the test four light treatments were applied: 

• SON-T lamps above the crop (reference)
• LED’s above the crop
• SON-T above, with LEDs between the crop
• LEDs between the crop and above

Practical experiences of Rosaline Zuurbier:

• In general, the company was very pleased with greenhouse growing under LED lighting because the production was clearly higher than for SON-T.
• The LED system was installed in November 2008. In the beginning there were problems with the fuse of the LED lighting system, but once that was remedied the system worked well.
• In December, when the outdoor temperature dropped moisture problems arose in the greenhouse. There was inadequate ventilation so the crops could not it contained moisture evaporate. SON-T was among the crop sufficiently warmed up, but remained below Led to cold, causing humor leaves’ were created.
• After installing an additional heating pipe (max. 40 ⁰ C) above the exposure arose between no new leaves more moisture.
• The water in the cold water pipes for cooling the LEDs was so cold that condensation formed, which dripped on the crop. Use of warmer cooling water, however, results in a lower yield of the lamps.
• During the trial it was noticed that the upper leaves were thick, stiff and dark green.
• Because of their enthusiasm for the test, the employees had no problems working with LED light. But the impact on health of prolonged work under these light conditions requires more attention.
• There was no difference in durability between the different treatments