At the Delphy Improvement Centre, researchers are exploring the interface between vertical farming and traditional greenhouse cultivation. As part of the Fieldlab Vertical Farming 2.0 project, a recent cucumber propagation trial aims to answer a key question: How does light quality during indoor propagation impact plant performance later in the greenhouse?
"The goal of the project is to develop more knowledge about vertical farming. We are doing collaborative trials with different partners, but we also try to answer questions of our own," says Brigit den Bakker, Researcher at Delphy. "In every trial, we look for the best crop and resource efficiency when it comes to light, energy, and water."
© Delphy
The focus on propagation in year two of the project
Now in its second year, the project has narrowed its focus to propagation. This essential stage in crop production is being studied from two perspectives: how efficiently propagation can be carried out indoors, and which light spectrum leads to the best results once plants are transferred to a greenhouse.
"This year, we focus on propagation material," she explains. "One side of the trial is to see if we can grow similar plants more efficiently indoors. The other is to see which spectrum propagators should use in their greenhouse to reach the optimum outcome."
From small trials to scaled testing
Delphy began the process with small-scale trials in 7.2 m² indoor cells. These early experiments helped the team understand how cucumbers respond to different light conditions in a controlled environment.
"We started by running several small-scale trials to see what happens under different light spectra and to get familiar with the propagation process," Brigit shares.
After gaining initial insights, the trial was expanded to the multilayer facility at the Improvement Centre. The facility includes five towers with four tables each, covering a total of 68 m². The team tested two different light spectra and two planting densities to examine efficiency.
"We saw that more red light in the spectrum, combined with a higher planting density, is more efficient than giving more blue light with a lower planting density," she says.
© Delphy
Transition to greenhouse cultivation
Once propagated, the cucumber plants were transplanted into an unlit greenhouse using an umbrella system. A set of reference plants from a commercial propagator served as a control group for comparison.
"Our own plants flowered earlier and started producing also earlier," she notes. "It is too early to say what the difference is, but we are excited to see the results."
With fruiting underway, the team is closely monitoring development to compare growth patterns, flowering times, and yields.
Challenges and next steps
While the trial has shown promising results, timing remains a challenge. The current indoor protocol takes 28 days to produce transplant-ready plants, which are suited for winter conditions. The team is now aiming to shorten the propagation cycle to 21 days for summer compatibility.
As the first fruits develop, the research team is optimistic about what lies ahead. The ability to trace the effects of light quality from propagation through to yield could offer valuable insights for vertical farming and greenhouse operations alike.
"It's exciting to see how propagation indoors affect the cultivation in the greenhouse," Brigit mentions. "The differences in growth, flowering, and eventually yield will give us powerful information for improving propagation strategies."
The project Fieldlab Vertical Farming 2.0 is a collaboration between government, industry, and academia: Delphy, Greenport Horti Campus/Greenport West-Holland, Growy, Inholland University of Applied Sciences, Logiqs, Own Greens, Signify, Vertify, and Wageningen University & Research. The Fieldlab Vertical Farming 2.0 is supported by InnovationQuarter, the Province of South Holland, Kansen voor West, and the European Union.
For more information:
Delphy
Brigit den Bakker, Researcher
B.denbakker@delphy.nl
info@delphy.nl
www.delphy.nl