Can you grow cut chrysanthemums using only red light?

Signify (Euronext: LIGHT), the world leader in lighting, has launched a trial in collaboration with Wageningen University & Research (WUR) to investigate how dynamic light recipes can be used in cut chrysanthemum cultivation, with the aim of achieving high quality with the most energy-efficient use of lighting possible. Seven different light treatments are being tested on two varieties.

The arrival of new advanced Philips LED fixtures allows for more and more flexibility in terms of lighting. By controlling LED colors individually, the optimal and most energy-efficient spectrum for the specific crop can be selected at any time of day. Leontiene van Genuchten, Plant Specialist at Signify, explains: “Natural daylight contains enough blue and far-red for a chrysanthemum to grow well, while these are the least energy-efficient colors in artificial lighting. So it could be very interesting for growers to be able to turn them off or dim them when the crop doesn't need them.” That is why Signify wants to see if it’s possible to grow cut chrysanthemums with mainly – or even only – red light.

In the trial, the popular spray chrysanthemums Chic (Royal van Zanten) and Baltica (Deliflor) will be tested under the influence of various different light recipes in combination with natural daylight. A lot has already been written about using far-red light at the end of the day to improve stem elongation in chrysanthemums. This application of dynamic light has quickly become standard practice. At the beginning of cultivation, stem elongation is desirable, but towards the end, a compact flower cluster is preferred. This research is studying the options of using extra blue light to fully or partially replace the use of plant growth regulators. After harvesting, factors such as stem length, stem weight, and number of open flowers per stem are measured, counted, and evaluated to come to a conclusion.

Udo van Slooten, Business Leader Horticulture LED Solutions at Signify: “As far as we’re concerned, dynamic lighting is the way to go. So, we’re looking forward to the results of this study, in order to gather more information on the optimal combination of natural daylight and LED light. This knowledge will not only be useful for chrysanthemum cultivation, but also applicable to other crops.”

The varieties for this trial were planted on February 12, 2024, at the Innovation & Demonstration Center (IDC-LED) in Bleiswijk, a partnership between Signify and WUR. The trial will be open to invited guests at various times.

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