Is lighting one of the elements you think of when it comes to plant nutrition? If not, it should be, says Dr. Abhay Thosar, Philips Lighting’s senior plant specialist for North America. He is working one-on-one with growers across the country to optimize plant nutrition by incorporating everything from the usual suspects of growing media and water to LED lighting. He says lighting is the often last frontier for many growers when it comes to plant nutrition.
“Lighting is definitely the next step with growers,” Thosar says. “Once growers gain knowledge of supplemental lighting or photoperiodic lighting, they can see how the plant responds to the right light spectrum, and how the right light can help them meet their growing objectives.”
Custom Solutions Necessary For Any Grower
While light emitting diode (LED) technology has been around for about 50 years, relatively speaking, the application of LED lighting in horticulture is new and still in its early stages, Thosar says. The technology has been incorporated widely in Europe, but the difference there is the monoculture crop production. In the U.S., where growers are harvesting multiple cultivars of multiple crops, there is much to learn about how to apply lighting technology, he says. For some growers, making the switch to LED lighting in a greenhouse is a big change.
“The lighting spectrum, intensity and duration varies. A lighting recipe needs to be developed for a specific crop based on the geographic location, production cycles and light requirements during those periods, but also to accommodate a wide range of cultivars and crops,” Thosar says.
No two greenhouse operations are alike. Even in the same city, greenhouses can have different growing environments depending on the plants that are grown. That’s why working with growers to develop plant growing recipes is so important, Thosar says.
“We work with each of our customers to develop a custom light solution and help growers really understand the importance of light,” he says. “Most importantly, we help growers use light most efficiently to optimize their growing.”
Seasonality is another important factor for customizing lighting. In northern climates, where peak retail sales for most annuals and perennials is March through June, growers need to have saleable product ready to deliver for the peak season in May. The production cycle of most perennials must begin from November to December, and production of annuals and bedding plants begins in late January. But in the northern U.S. and Canada, this is the time of year with the least amount of natural sunlight.
“It is late sunrise, early sunset, shorter duration and less light intensity,” Thosar says. “There is not a sufficient intensity of sunlight, and even if there is sunlight, from a plant’s perspective, it is not the optimum quality of light. It is during the low light period that growers need to provide supplemental light to their crops.”
When he meets with growers, the first thing Thosar says he attempts to learn is the objective they want to achieve by using supplemental or photoperiodic lighting. This could include anything from reducing the crop cycle or reducing the use of plant growth regulators to improving rooting conditions, improving rooting percentages or having more consistent growth in plug trays or more compact plugs.
“Compact plugs make for more attractive plants and attractive, healthy plants that sell better and faster,” Thosar says. “We also have growers who are interested in managing their energy costs or to control light and heat as independent elements.”
Once he has an understanding of a grower’s priorities and objectives, Thosar begins working on incorporating them into the light requirements and other factors that need to be optimized, he says.
“This is typically based on production volume and customer demand of particular cultivars, and allows us to discuss specific light requirements of specific crops,” he says.
Grower Trials Are Showing Improved Plant Quality With LEDs
Thosar says the lighting recipes Philips has provided to growers have shown good results. Walters Gardens in Michigan reduced its use of plant growth regulators (PGRs) on heuchera and sedum, and noted an improvement in lateral and basal branching, which reduced the need to shear the crop, saving labor.
“Walters Gardens also noted better survival of plants in hibiscus, heuchera and echinacea plug trays,” Thosar says. “That saves the time of having to sort through plug trays.”
Bordine’s Nursery in Michigan also reduced PGRs in trials with Philips’ new toplighting product for propagating begonias, and the begonias rooted faster, Thosar says.
At Battlefield Farms in Virginia, where Research and Development Manager Travis Higginbotham used Philips LED production modules to test heuchera cultivation, the results showed an improvement in propagation rates.
“Travis saw a 100 percent success rate with the ‘Blackout’ cultivar, a 92 percent success rate with ‘Caramel’ and an 85 percent success rate with ‘Citronelle,’” Thosar says. “This helped Battlefield to meet transplant dates more efficiently.”
LED Offers Labor Savings As An Indirect Benefit
With the current labor shortage and lack of qualified growers available, plant recipes using LED lighting technology are also helpful, Thosar says. This is not to discount the importance of having knowledgeable and educated growers, which is very important, he says; however, findings from trials with Philips LED toplighting this past winter have shown significant labor savings.
“[It] resulted in more compact growth of plugs and a more consistent plug tray, meaning fewer losses,” he says. “This can translate into reduced use of chemicals and reduced use of PGRs, which in turn is a reduction in labor, as well as eco-friendly. A consistent plug tray offers a labor savings from the bottom line because you do not have one person going through the plug trays to find and pull plants that will not survive transplant. The labor savings comes from such things as less time spent applying chemicals or PGRs and less time picking through trays.”
Do Your Research And Ask Questions About LED
With so many LED products on the market, it’s tough to know where to start. All products are not created equal, Thosar says, and growers should be careful not to risk buying a standard, one-size-fits-all application, he says. Instead, do your research, talk to manufacturers and be sure to trial products before making a commitment.
“Far red, deep red, white, low blue, medium blue, high blue — there is much to learn about the LED light spectrum and how plants grow under LEDs,” he says. “For example 400 to 500 nanometers wavelength is blue for human eyes; however, the photosynthetic pigments do respond to certain wavelengths optimally, and all LEDs will not yield similar results. Different manufacturing companies will deliver different results.”
Thosar says even he is still learning, despite working with plants for more than 12 years prior to joining Philips, and three years working to understand how plants interact with light, as are university research authorities on lighting like Dr. Erik Runkle at MSU and Dr. Roberto Lopez at Purdue University.
“We are all still learning,” Thosar says. “Regardless of the manufacturer, growers need to do research themselves. A bad experience or bad product is just that. I hope growers who have tried LEDs and not experienced improvements will look again at another LED supplier. We have been able to provide definite results and proof of research, and that is why we want to work closely with growers to make sure they do a proper trial and set up the trial correctly.”