Photo courtesy of Creekside Nursery

Jerry Simpson, who co-owns Creekside Nursery in Dallas, North Carolina with his wife Jenny, says the retail side of the business is what primarily drives sales. That includes annuals and perennials grown in greenhouses, but also shrubs and trees produced outdoors.

Annuals specifically, he says, account for about 70% of what Creekside grows under cover. Much of that product is geared towards the busy spring season. That’s true even this year, when sales have been different amid the on-going coronavirus pandemic. Simpson adds that Proven Winners is the main supplier of the company’s annual varieties.

“We’re known as a destination around here for Proven Winners annuals – and perennials too,” he says. “It brings people in.”

Creekside has been working with Proven Winners since 2013’s sell season when Simpson began looking at what he was planning to grow for 2014. When he was shopping around, he was looking for 4” offerings to fill bench space.

“I found Proven Winners’ retail resource guide,” he says. “So I found that, and it was all laid out for us. We used, and still do, use all that marketing power from the tags to the supplemental stuff that they have on their website that we use on ours and in social media. All of it’s there for us.”

When growing Proven Winners annuals – including Supertunia® and Superbells® – he says they’ve all been easy to grow. Additionally, Simpson says there’s an added benefit in knowing the plants he’s growing have been tested for quality and proven to sell.

“They put all the work into figuring out what’s going to sell or doesn’t sell,” he says. “It doesn’t become a Proven Winner unless it goes through the whole trial process.”

As for the varieties, Simpson loves the Superbells® – a calibrachoa that grows between 6” and “10 – because it performs great in hanging baskets.

“From ‘Holy Moly’ to ‘Tropical Sunrise’, we love those in hanging baskets,” he says. “Very compact, easy to grow.”

“We plant it in the landscape or in hanging baskets and people love it,” he says. “Particularly with ‘Bubblegum’, it’s flower power is incredible. And if you can establish the plant early on, it has such a vigorous root system that it’s going to get itself well-rooted so the customer is going to happy. And that’s what we want.”

Photo courtesy of Erico Mattos

Greenhouse Management: How did you end up specializing in researching LEDs and supplemental lighting for greenhouse production?

Erico Mattos: I came to the U.S. to do my Ph. D. at the University of Georgia starting in 2009 and I was part of the biodiesel program at that time that was run out of the University of Georgia. My part of that project was to optimize biomass. I was using light, primarily different colors of LEDs, to optimize biomass in algae for the research. I thought that was interesting, but that work wasn’t having a massive impact on biodiesel. So that’s when I started to look at greenhouses and plants and seeing how that lighting technology could be applied to growing.

GM: You came to the U.S. from Brazil. What was, and is, that like?

EM: I came to the U.S. via a partnership between the University of Georgia and the University of Sao Paulo, where I’m from, and a private company in the bioenergy space. The whole experience was very nice. I’ve been able to expand my view of the world and see what’s different between here and Brazil — good and bad things on both sides. ... I knew very little English when I came here for the first time, so that really made me work hard. When you go to grad school, and have an assistantship as I did too, you have to keep up good grades. So I worked hard and also consider myself lucky for ending up where I did and doing what I do. ... What I do has a small community too, so I’ve been able to get to know a lot of people and all of them are really, really nice people. I’ve been accepted openly into this horticultural field.

GM: What has it been like maintaining research amid the pandemic?

EM: I wear two hats today. I work as the director of the GLASE consortium and run a small lighting control company, Candidus. So with the former, things haven’t changed for me all that much. Some of the research we’ve been doing was considered essential, but some wasn’t, so some of it was delayed. A lot of my time has been restructuring and adjusting our plans. On both fronts, I’ve spent a lot of time keeping my ears open and trying to help the industry and figure out what it needs right now.

Photo © Mulderphoto | Adobe stock

With just over two-thirds of commercial greenhouse managers surveyed indicating plans to replace, expand or invest in new supplemental lighting technologies in the next three years (67%), it naturally begs the question: How do you evaluate the many different options on the market today?

The University of New Hampshire Cooperative Extension recommends that growers set up small-scale trials throughout greenhouses to evaluate which species and cultivars are more profitable under supplemental lighting.

AJ Both, extension specialist at Rutgers University, has been undertaking advanced horticultural research projects since the late 1980s. His advice for commercial growers looking to conduct their own research on plant response to different types of lighting systems is simple Find an expert.

“It can be helpful to consult with an expert who understands plant lighting, because plant lighting is quite different from lighting applications for human environments,” he says.

“I think that conducting trials make a lot of sense when specific benefits are expected,” Both adds, noting that “there is some published research data that can be helpful, but the number of plant species and their cultivars is large.

“Chances are, conducting trials is the only way to determine what the optimum light environment is for a specific plant species,” he says.

Choose your sensor wisely.

Both notes that it is crucially important for those conducting supplemental lighting research to recognize the fact that different plants and cultivars respond quite differently than our own eyes to various sources of light.

Therefore, one cannot simply rely on human observations. Finding the right sensor to capture the right data set is key in any supplemental lighting trial.

“Don’t use a foot candle or lux meter, but instead use a quantum sensor,” he says. “A quantum sensor produces a reading that informs about the intensity of light that plants can use for photosynthesis.”

Once you zero in on the right sensor suite for your operation, a good place to start is using the sensors to obtain a solid understanding of the level of uniformity of light distribution over the entire growing area, Both says.

“Researchers typically achieve this through so-called light maps, which measure the distribution of light across a horizontal plane located some distance below the fixtures,” he says. “Measurements taken are then distributed across the measurement plane using a uniform grid, and simple statistical tools can then be used to calculate light uniformity across the entire area.”

Know your ideal spectrum.

Different plant cultivars respond independently to different spectrums of light. Some prefer red and blue spectrums during vegetative growth, while some need a healthy dose of infrared during flowering.

“If it is important to know something about the spectrum, or the color distribution, of light in the greenhouse, you can use a spectroradiometer,” Both says, noting the use of these instruments is not entirely common in commercial greenhouse applications.

“Ask for assistance from local researchers, or even from a lighting manufacturer who has experience in this area,” he says.

Identify variance across your canopy.

One of the most tangible benefits of conducting your own supplemental lighting trials is the ability to collect data in the same environment where the system will eventually be placed. This is often more valuable than research that takes place in a clinical setting where conditions are often more controlled than in a typical commercial greenhouse.

“When collecting these light readings, it is important to understand that in most cases light measurements will exhibit both spatial and temporal variation,” Both says. “In other words, time and location of the measurements taken are important.”

In order to diminish the influence of variation during the trialing phase, light measurements should be conducted over longer time periods (days, weeks, months) so as to reduce, or “smooth out” instantaneous variations, according to Both.

“As much as possible, sensors should be located where there is minimal shading taking place from the plant canopy, or even from stationary or moving overhead equipment like spray booms,” he says.

Both also notes that, when measurements are being conducted over long periods of time, sensor location adjustments are usually a necessary evil to ensure the data being collected is free of shadows and other obstructions throughout the process.

“This is also necessary when the canopy starts growing out and covering a sensor,” he adds.

Another issue that can pop up when trialing supplement lighting systems is the physical location of the experiment itself. Because the number of light sensors used during these evaluations is “typically small,” Both advises that “it becomes important to consider a location that is representative of a larger growing area.”

It’s a tough reality to face after a long period of upheaval: the economic effect of the COVID-19 virus may unfortunately force you to shutter some greenhouses this winter.

The impact of severe weather and the prolonged exposure to the elements can cause significant damage to a closed greenhouse, most of which are designed by code to maintain a 50° F minimum temperature.

Here are some pointers to help minimize damage to the structure and equipment:

1. Visually inspect the exterior of the greenhouse to see that it will keep the snow and rain out. Replace cracked or broken glass. Tape tears and seal leaks in the poly cover. Check to see that the plastic is attached securely and that any holes are taped. On air inflated greenhouses, increase the inflation pressure slightly when snow or strong winds are predicted by opening the blower’s intake valve. This will reduce the rippling effect. Weatherstrip and fasten doors so they can’t be opened by the wind.
2. To support wind and snow loads, check that the frame is secure. Tighten truss connections, frame bolts, straps and bracing. In heavy snow country, add a row of wood 2 x 4’s under the ridge on hoophouses to support heavy wet snow that would normally melt and slide off when the house is heated.
3. Decide whether to provide minimum heat or shut the heating system down. If you have a boiler system, it may be better to keep the heat on and set the thermostat at 35° F. This eliminates the need for draining the system and blowing out the pipes. It may also prevent seals, gaskets and valves from drying out. A plastic shelter over propane and fuel oil tanks can provide protection, or adding methanol to oil will keep the fuel more viscous. For hot air furnaces typically used in hoophouses, they can be shut down without problems. Turn off the oil supply valve.
4. Check vents and shutters, ensuring they are closed tight. Inspect roof vents and roll-up sidewalls for leaks or gaps that would allow wind and snow to enter. Fan shutters should be covered with a sheet of plastic or insulation board. Cover evaporative cooling pads and drain tanks, piping and valves.
5. In southern climates, a closed greenhouse may overheat on a bright, sunny winter day. This may be fine for reducing insects and diseases, but it can also damage plastic piping, deteriorate shade material or warp plastic benches. Vents or fans may have to be operated on these days.
6. Energy/shade screens should be open. The sun will warm the greenhouse and soil on clear days and keep the frost penetration to a minimum. It will also provide protection to the screen material to reduce deterioration. If you are running heat then close the screen (unless snow is predicted).
7. Electric power and controls may still be needed when the greenhouse is buttoned up. The power and smoke/fire alarms should be checked frequently to insure they are working. Heat may be needed to melt and remove a heavy snow load.
8. Remove pesticides, fertilizer and other chemicals that could be affected by cold temperature. Check Safety Data Sheets (SDS) for storage requirements. Many chemicals have minimum/maximum storage temperatures and light exposure requirements.
9. Provide rodent control. Mice, chipmunks and squirrels may enjoy the mild climate of a vacant greenhouse. Set traps and baits.
10. Get ready for Spring. The winter is a good time to do needed maintenance. Remove all debris left from the previous crop, dispose of all used containers and powerwash benches. Pick a warm day during slack time to service and repair equipment. Check operation of heating and cooling equipment, calibrate controls, tighten up doors and vents and make needed structural repairs.