Roses are red, violets are blue, they say. But in fact, other plants can also benefit from red and blue colors. Blue and red LED light can be used for growth retardation and both shorten production time and optimize plant growth more effectively than chemical plant growth regulators. This has been shown in trials with Spanish daisies conducted by DGT by Senmatic and a local nursery.
From the production of cuttings to further propagation at the rooting station and from there to final production in the nursery. There are many processes before the end customer buys a Spanish daisy in their local store. But replacing chemical plant growth regulators with LED lights speeds up the whole process. The shorter production times in the nurseries make room for more plants to be sold to retail buyers.
The result: Shorter production time without the use of growth regulators
The results from the trials with LED light as a growth regulator replacement were convincing, but also surprising. In addition to greater uniformity, production time was also optimized from the usual 4-6 weeks from cutting to resale of seedlings to 3-5 weeks. The shorter production time means more rounds of production on the same square meters and thus has the potential to increase sales.
“I was surprised to be able to produce a lower and more marketable seedling without the use of a growth regulator and solely with the use of LED,” says Jesper Slot, former owner of the nursery where DGT by Senmatic carried out trials with LED and today CEO of Graff Young Plants.
“In addition to being able to produce more plants per square meter and thus increase our sales, we were also able to meet the growing interest and demand for small plants produced without the use of growth regulators. Using only LED lights as a growth regulator gives you a product that you can promote as pesticide-free in addition to fungal spore control. Reducing the use of chemicals is a chain responsibility and something the entire chain from rooting stations to nurseries and buyers should improve together.”
Jepser Slot CEO at Graff Young Plants
These many factors must also be taken into account when calculating the investment of replacing traditional HPS lamps with modern LED lights.
“It’s not just power savings you need to look at when investing in LED. Our customers experience less shrinkage, less retardation and more uniform plants. Factors that all result in optimizing the horticultural workflow as well. You have to calculate the total savings.”
Morten Hjorth Area Sales Manager at DGT by Senmatic
Here’s how we did it: LED as a replacement for chemical growth regulators
The idea of using LED light to replace chemicals began to germinate in Jesper Slot, former horticultural production manager and now CEO of Graff Young Plants, after he had been in contact with DGT by Senmatic and learned that LED could provide good results for plant growth and growth regulation. Together, a trial on the effect on Spanish daisies was launched in a small test house in the nursery Jesper Slot co-owned.
In small chambers in the nursery, which produced millions of Spanish daisies for sale throughout Europe, four varieties of Spanish daisies – or osteospermum, as they are called in horticultural language – were placed under LED light in week 8 of the plant from 05:00 to 21:00 at a temperature of 16 degrees. All varieties had reference plants that were regulated in the traditional way with plant growth regulators in order to compare the results. Research has shown that red light stimulates rooting and therefore “stretches” the plant, while blue light “pulls” and therefore affects height.
– There has been a lot of research into the use of light in agriculture and the plant sector. It has been found that blue light most often results in compact growth, while red light results in stretching growth. However, there can be differences based on the culture – for some plants it can actually be the other way around. We know, for example, that the opposite is true for tulips,” says Morten Krage, while Jesper Slot agrees: “It is well known in the industry that the colors of LED light can affect plant growth, but there are still some unanswered questions and no research has been done on all types of plants. That’s why we set out to investigate this for Osteospermum, which we produced for the whole of Europe,” says Jesper Slot.
With the Osteosspermum variety Emma, repeated trials were conducted with plants with different LED light compositions and reference plants with HPS light and traditional growth regulators. The image shows the difference between a reference plant with plant growth regulators and HPS light (left) and a plant growth regulated with LED light only (right).
Examples of test results – Sunny Osteospermum Emma:
Below are the concrete results of the trials with the Emma variety. The three tables show how the amount of blue light affects the plant. Note that only the light composition changes – the controllable light composition is easy to change with an LED controller or DGT by Senmatic climate control. The reference plants have all been treated 6 times with traditional growth regulation and have received HPS light. It is worth noting that even with a fixed LED light strategy, remarkable results are seen.
“It is thought-provoking that by using LED light you can completely eliminate chemical growth regulation on Osteospermum during propagation,” says Jesper Slot.
In addition to the trials with the Emma variety, similar trials have been done with the Sunny varieties Atilla, Galina and Carlos.
What is growth regulation?
Growth regulation makes changes in the plant’s cells and has an impact on how the plant will look. For example, growth regulation can affect the plant’s height, the distance between the plant’s leaf pairs or how bushy the plant becomes.
Why do you do plant growth regulation?
Growth regulation of plants is done to make the plant more marketable to the buyers who purchase for e.g. supermarket chains, and to the end customers who buy the plants in stores. For the buyer, it is particularly important that the plants are compact rather than tall and unstable. Low, compact plants make it possible to transport several plants at a time – transportation that is often done in standardized CC containers.
Are you considering LED?
DGT by Senmatics LED top light is available in many variants, including luminaires with lens systems. Our solutions fit into most modern commercial greenhouses around the world and are designed to withstand the demanding environment of a greenhouse and continue to perform for years. The minimalist design makes the luminaires easy to install and connect using standard technology, and they provide a minimal shadow effect.
In addition, with controllable LED lights from DGT by Senmatic, the nursery can control and adjust the spectral distribution. This means that when you invest in a controllable LED luminaire, you always have the option to change the light, for example due to new research results, in line with (new) cultivation stages, or simply because you want to dim the luminaire when less light is needed. If you invest in controllable LED grow lights from DGT by Senmatic, you will not be limited to a specific spectrum, but have unlimited possibilities.
Some of the highlighted benefits are:
- Spectral distribution control and dynamic control of light intensity
- Multiple variants for multiple applications such as vertical farming, greenhouses, enclosed spaces, garden centers, production areas with special lighting needs, hybrid installation, indoor environmental planting, green walls – and much more
- Savings on energy
- Long lifetime with no reduction in light output over time
- Constant light on the plant due to a patented optical lens system
