Growers invest a large amount of capital into their greenhouses, equipment and even automation to create an efficient and profitable grow. An operation could have the most high-tech equipment money can buy, but if they neglect their lighting, the grow can fall apart and the operation will end up losing money on energy costs and unhealthy crops.

Supplemental lighting is an integral part of any grow operation, and a proper lighting plan ensures that the lights are perfectly configured in order to deliver even, uniform light throughout the greenhouse in the most effective and efficient way possible.

There are many important factors to consider when designing a lighting plan, including light intensity, plant requirements, greenhouse layout, greenhouse cladding and more. Each of these elements influences the lighting inside the greenhouse in one way or another, so a lighting plan needs to consider all of these factors in order to be effective and efficient. A comprehensive greenhouse lighting plan takes things such as crop needs, greenhouse layout and light intensity into account to ensure for uniform, even light distribution over all plants for a healthy and thriving grow.

How to create a comprehensive lighting plan

Before getting into specific lighting plans, it is important for growers to know the lighting options they have and choose the best ones for their specific crops and greenhouses.

There are four types of supplemental lighting that are most commonly used in greenhouses:

LED: LED fixtures are one of the longest lasting and most energy-efficient greenhouse lighting options. While their upfront cost may be a bit higher than other options, they will provide energy cost savings to make up for it, so growers can expect a return on their investment. LEDs have a lifespan of about 50,000 hours and higher end models even provide flexibility of the color spectrum.

"A lighting plan should be designed by a greenhouse specialist with specific greenhouse lighting experience. — Janine Coppola

High pressure sodium: High pressure sodium, or HPS, fixtures are a type of high intensity discharge (HID) lighting, which means they give off a bright and intense light to crops. They provide a good spectrum of light to crops and are efficient and a popular choice among greenhouse growers.

Ceramic metal halide: Ceramic metal halide fixtures, another form of HID lighting, are similar to HPS fixtures. They offer a similar intensity to HPS fixtures, but provide intense blue or white spectrum light, and are well-suited for vegetative growth stages. These lights are ideal for locations that lack natural light.

T5: T5 fixtures are more efficient and compact than their more traditional, older fluorescent counterparts. These full spectrum fixtures are ideal for greenhouses with an absence of natural sunlight and are beneficial for large areas due to their efficiency. They also work well for propagation.

Growers need to consider the spectrum of light their crops need when choosing their lighting fixtures and designing their lighting plans. The spectrum of light necessary for growth varies from crop to crop, and different lights will generate different color spectrums.

For example, a lettuce grower might only need metal halide fixtures since lettuce does not need to flower like a tomato or cannabis plant would. Growers of flowering crops, on the other hand, would need high pressure sodium or full spectrum LED fixtures. Higher end LEDs work well for smart lighting applications, as the color spectrum can be adjusted or changed based on the growth stage of the crop. And light intensity can be dimmed for various stages of growth.

After lighting is chosen, it is time for growers to create their greenhouse lighting plan. It is important to note that a lighting plan should be designed by a greenhouse specialist with specific greenhouse lighting experience. This will ensure that the plan is designed for maximum efficiency and will properly function for the needs of the crops, while boosting the operation’s profitability.

3 factors you must account for

There are many factors that must be taken into account when designing a greenhouse lighting plan. Adrian Valois, greenhouse specialist at GrowSpan Greenhouse Structures, cites three key considerations for growers to keep in mind when creating their lighting plan.

“The first thing that you need to think about is your crop. Different crops have very specific needs when it comes to the right spectrum of light they need to thrive,” he says. “Second, you need to have a layout for your crops, so that you can maximize each light fixture being used. Third, you need to have the right wattage and coverage for each light.”

The greenhouse’s layout has an immense effect on its lighting plan, so growers should try to maximize each light by having a good crop layout. For example, if crops can be grown in a 2- by 2-foot area instead of a 3- by 3-foot area, growers can have 25 plants under supplemental lighting instead of 10. Based on how plants and equipment are situated throughout the greenhouse, lighting placement needs to be adjusted in order to reduce shadows and deliver the maximum amount of uniform light to the crops in the most efficient and effective way possible.

Equipment around the greenhouse or even the light fixtures themselves can cast shadows on the crops below, limiting the light they can take in. When lighting is not properly hung, rafters and purlins can cast shadows as well. It would be counterproductive for a grower to install light fixtures only for their shadows to hinder their crops from taking in that light.

Light intensity is of paramount importance when a grower is creating a lighting plan. The light intensity needed by different plants varies, and too high or too low light intensity can be detrimental. Finding the perfect light levels for the crops and the right light coverage will ensure plants thrive.

“Light intensity is more important than the number of fixtures. The right light will provide more coverage, resulting in less fixtures,” Valois says. “More wattage usually results in fewer light fixtures and same quality, so this is highly recommended.”

Another factor to consider is the heat that the lighting fixtures give off. Certain crops may benefit from added heat and growers may even end up saving some money on heating costs. Other crops may not need the heat, especially if the greenhouse is already located in a warmer environment. Growers should consider what temperatures their crops thrive under and how much heat their lighting choice gives off when designing their lighting plan.

“Heat actually helps a lot of growers who only need supplemental lighting during the colder months,” Valois says. “Having a good spread will also help reduce heating costs inside your greenhouse, especially if using high pressure sodium or metal halide fixtures, but you might have to place them a little higher than if you were to use LEDs.”

Different claddings have different light transmission rates, so growers should take their specific cladding into consideration when creating their lighting plan. A greenhouse that has cladding with a lower light transmission rate may need more supplemental lighting than a greenhouse that has cladding with a higher light transmission rate. Growers should also consider the R-value, or heat retention, of their cladding as their lights may give off heat that will then become trapped within the greenhouse if their cladding has a higher R-value.

When creating a lighting plan, growers should think ahead and consider the possible expansion of their operation. Keeping this in mind from the beginning will make the expansion process easier down the line.

“If a grower is expanding, keep in mind the coverage of each light fixture when doing so,” Valois says. “This could save growers a lot of money if they expand by the right amount.”

Key grower takeaway

A comprehensive lighting plan considers every aspect of the greenhouse and the crops to ensure the even and uniform distribution of light for the healthiest grow possible. With all of these factors being taken into account, the perfect lighting plan can be designed for an efficient, effective and thriving grow.

Janine Coppola works for GrowSpan Greenhouse Structures. For more information visit www.GrowSpan.com.

Lone Star State growers and greenhouse operations are picking up the pieces after an unexpected mid-February winter blast saddled producers with in an estimated $600 million in agricultural product and revenue losses, according to initial estimates from Texas A&M AgriLife

The biggest hits were taken by the state’s most prominent field crops — citrus, cotton, trees and shrubs and vegetables — but nearly a fortnight of below freezing temperatures felt as far south as Brownsville, Texas, also damaged many of the state’s nurseries, garden centers and greenhouse operations.

“The green industry will experience increased labor, fertilizer and other costs as part of the price of replacing the plant material that was lost during the winter storm,” said Marco Palma, Ph.D., horticultural marketing expert in the Department of Agricultural Economics.

“The green industry has had severe damage, especially in some of the larger metropolitan areas such as Houston, Dallas, San Antonio and Austin,” adds Amy Graham, president and CEO of the Texas Nursery and Landscape Association (TNLA). “We have a lot of nursery plant growers in East Texas and quite a few of them have reported total losses. In some cases, complete greenhouses collapsed. In other instances, plants died because there was no propane for heating greenhouses.”

How they prepared

Ben Van Wingerden, Color Orchids’ founder and CEO, recently relocated to Texas to help open a new southern production greenhouse. Call it a stroke of foresight genius, or perhaps it was mere coincidence, but Van Wingergen and Co. made the prudent decision to outfit their structure for the same climate and weather conditions they dealt with on the Eastern Seaboard. That decision paid off big-time this winter.

“The builder, Prins Usa, built the greenhouse here as if it were located in Virginia,” Van Wingerden explains. “We engineered with a 3-foot snow load on the roof, and all the walls are insulated panels. All our water lines are buried deep enough to avoid freezing. And we put in natural gas lines and a backup fuel source, and we also have a 400-kw generator.”

Even with all those precautions in place, the team at Color Orchids remained concerned as they monitored the weather forecasts and planned for the coming storm. Orchids are, according to Van Wingerden, notoriously sensitive to temperatures below 65° F.

“Our biggest concern was the extremely low temperatures, because when you build new, you size your boiler based on a certain outside temperature in relation to your desired greenhouse temperature,” he recalls. “Orchids are sensitive, and the temperature can’t fall below 65. When I was designing the facility, I picked an outside temperature of 12° F for the lowest temperature it can get.”

So, the facilities’ boiler for heating the greenhouse was sized and installed, and a backup boiler for “redundancy and expansion” was also added into the mix. Still, even with all those precautions in place, something continued tugging at Van Wingerden.

“I was concerned that if one boiler went out, then the backup boiler would have trouble maintaining the proper temperature,” Van Wingerden says. “So, that meant everyone had to remain on standby in case a boiler decided to go out on us.”

The crew also fired up and monitored the facilities’ backup generator in the runup to the storm.

“We also wanted to confirm that the generator had been properly winterized by the company that services our generator for us, and then we just went around and insulated everything outside with foam, hay, and covers, that we thought could freeze.”

How they fared

Color Orchids, known in the industry for its Simple Shot and Simple Wick watering systems, thankfully came through the storm and subsequent power outage virtually unscathed, according to Van Wingerden.

“The end result of all of this, for us, was a big win,” he says. “Of course, you do lose growing days, but in the scheme of things that is nothing compared to what could have happened. Our structure held up, we kept the power on, and we didn’t lose our crop.”

Where a lot of Texas-based horticultural operations saw big problems during Uri was with freezing and malfunctioning irrigation lines, storage wells and systems. ColorOrchids came through cleanly in that regard, as well.

“We treat our well water for irrigation water, and we use a storage tank which is kept inside the greenhouse, so we did not encounter any irrigation issues,” Van Wingerden says.

How things look for 2021

It’s the question on the tip of everybody’s tongue down in Texas. How will plant availability be affected? Will the new plant parents still be able to seek out and grow all of the varieties they want this spring?

“I think that will be interesting to see,” Van Wingerden says. “I just read an article claiming the state will suffer around $600 million in ag product loses. We have already heard from our neighbors and partners around the state that there are some places being affected pretty badly, but I couldn’t tell you what kind of impact it will have overall yet.”

One prediction he will make, however, is any disruption will likely exacerbate some of the supply chain issues the industry felt in recent months.

“There was already a large disparity between supply and demand right now in our industry, so any additional shortage will just widen that gap, and it should drive prices up,” he says. “If I had to make a prediction, I would say the retail stores will continue this trend of increased sales of everything plant-related, and these stores will be searching high and low for product to put on their shelves.”

What they learned

Always have enough back up fuel and energy sources, Van Wingerden advises.

“It’s honestly not a huge up-front investment, and I was very happy that we could switch to propane if natural gas prices got to high, and we could run the generator if our kilowatt price went up to high,” he explains. “Well, that happened. In some cases, the electric companies in the state [Texas public utilities are deregulated] were charging 650x their normal kilowatt price. For us, that would’ve been an over $1-million electric bill.”

How they prepared

Native Texas Nursery grows ornamental crops, perennials, shrubs and young trees for wholesale dealers and distributors both in the field and under cover. The wholesale plant producer leverages 28 single layer poly covered cold frame “greenhouses” as well as a modern, double gutter connected propagation greenhouse.

According to owner Bill Carson, the operation has about 31 propane heaters — one for each cold frame as well as three staged throughout the propagation greenhouse — it relies on in the cold months to keep the crops above freezing and in vegetative growth mode.

“Our lifeline during the winter is keeping the propane coming,” Carson says. “We have about 3,000 gallons of storage capacity on site, and we have a very good propane supplier who will make regular trips to top us off during the cold months.”

The cold frames covered with poly that protect its perennial crops are maintained around 45° F, while the propagation house needs to keep a steady 60° F baseline to keep those young plants viable and developing.

“We knew from the forecasts that we were facing a long stretch of single digit temperatures, and when we get down to single digits, we tend to use about double the propane we’d normally need,” Carson says. “The storm was set to arrive on a Sunday, and the Friday prior, I did the math and went into a panic.”

Carson crunched the numbers and came away confident that the operation could handle three to four nights of single digit temperatures without completely running out of propane.

“We could handle four, but not five, not six nights in a row, and on top of that, a six-inch snow accumulation as well,” he explains. “When we get that much snow down here, everything shuts down and nothing moves anywhere — there’s not a single snowplow in this town. Well, this was going to stick around for six days, and our last propane delivery was on Saturday.”

Before that final load of propane arrived, Carson huddled up with his supplier and drew up a plan of attack: with travel set to shut down across the state for a few days at the very least, the propane supplier could lend Carson a 3,500-gallon tanker, full of propane, to keep on site in case they ran out during the week. The rep even came out and trained some of Carson’s crew members how to operate the tanker, and how to offload the propane into their storage tanks as needed.

How they fared

Due to the quick thinking and collaboration of Carson and his propane dealer, the operations lost very few plants during the storm.

“That was about 7,000 gallons of propane [delivered] that we got in here quickly, now that is what I call service,” Carson beams. “I shudder to think about what would’ve become of us if we did not have enough fuel to keep the heaters on.”

Keeping the heaters running was just the start of it, though. Carson had his crews staged around the clock to monitor fuel levels throughout the week, since 32 propane heaters all running at the same time can really chew through some fuel, fast. Then, once the snow itself arrived, the workers climbed atop the gutter-connected propagation house and shoveled the snow to keep it from collapsing the poly covering.

“Between what our propane guy did, and what our amazing staff did during the storm, we were able to save about 95% of the product, and that 5% of loss was a lot of the really young and tender stuff,” Carson says. “And now, we’re shipping out product like crazy.”

Pressed to take an educated guess at the level of losses the operation would have suffered, Carson says you have to measure in both dollars of product lost, as well as time and future product potentially ruined.

“It would have been in the excess of a couple million dollars of losses, and if we would’ve lost a bunch of plants in our propagation house that would’ve crippled us for at least another year on our tree crops,” he says. “Just the labor costs alone of having to remove and destroy all that material, with no new revenue coming in, would’ve been disastrous. It basically would’ve shut this company down for good.”

Native Texas’ unique approach to plant sourcing — the operation does not order genetics from seed catalogues; all of its varieties are sourced in the wild (hence the native moniker) — makes sourcing replacement plants quickly a virtual non-starter. The operation, with 50 full time workers, would have had to shut down and lay off its crew until fall, when it could get back to sourcing native plant seed.

“We would’ve had to let go of virtually all of those employees, it would’ve been a shell of a company compared to what we are today,” Carson says.

How things look for 2021

Of course, anytime you lose any amount of plants, it’s uncomfortable. Yet, considering the relatively minor losses that Native Texas experience compared to some of their Lone Star State neighbors, prospects for the next few months are looking up.

“We’ll take a bit of a hit, and it will take some real hard work for us to overcome that, but we’re relatively speaking in a pretty good place right now,” Carson says. “We have greenhouse material that is ready to ship out now that will bring in some immediate cash flow for the business.”

What they learned

Native Texas’ winter storm Uri experience certainly calls to mind the old saying: “an ounce of prevention equals a pound of cure.” By preparing before the storm hit, the team avoided some of the catastrophic losses others nearby in the green industry suffered.

That is a valuable lesson, whether you’re staring down a once-in-a-lifetime weather event or another Mother’s Day weekend mega-rush down at the garden center.

“We were prepared for this cold, but the amount of snow and just how long it stuck around, we couldn’t have been prepared for that. I’ve been in this business for 35 years and nothing that I’ve witnessed has approached the scale of this,” Carson says, noting the operations facilities spent a record 140 hours in a row below freezing.

Carson foresees a few notable developments coming out of this tragedy.

“People that are growing outside exclusively, I think they will really be looking hard at making some changes going forward,” he says. “For us, we will prepare better for propane pressure problems, we’ll probably add more storage tanks as well. And I think we’ll add some more backup heaters. My crew can hook those suckers up in just under 15 minutes. We’ll have brand new ones still in the box, ready to go when we need them.”

The greenhouse structures companies will surely be making some sales calls down in Texas this summer when the busy season winds down.

“I think that’s fair to say, more people down here will probably think a bit longer and harder about growing in a greenhouse, and we’re talking about adding more greenhouses here, too,” Carson admits. “But, at the end of the day we consider ourselves farmers, and farmers are always at the whims of the weather.”

Photo courtesy of ben collister

The month of December could play an important role in Ben Collister’s life if everything goes as planned. The sophomore at Delaware Valley University in Pennsylvania is slated to graduate in December of 2021, and would one day like to open a Christmas Tree farm/nursery.

“I’ve always been interested in Christmas trees,” says Collister, who won the Richard Foster Award, a scholarship available to outstanding students planning careers in the landscape, lawn care or horticulture business. “We’ve always had real Christmas trees growing up and that’s always been something that my dad’s wanted to do.”

While the Christmas tree goal is more long-term, the drive to diversify his father’s company, Collister Landscape Maintenance in Pennsylvania, is more urgent. As he works part-time at the company, he’s envisioned adding design/build to its service portfolio.

That makes sense, being that he is majoring in landscape design/build.

“This is laying the foundation — getting my degree here and then I definitely need to add employees,” he says.

He’s also interested into branching out into commercial work.

“I just enjoy bigger properties,” he says. “I also feel like it’s a lot more profitable — less drive time between properties.”

Collister has an entrepreneurial specialization, which is similar to a minor, in business. Taking those classes will come in handy since he hopes to eventually take on a managerial role at the company.

“There’s quite a few business classes that are part of that – principles of marketing class, I have a management concepts class, business law,” he says.

One lesson he has learned that a lot of landscapers struggle with is the balance between working on the business versus working in one.

“Eventually, I’d like to move into more of a management type position where I oversee stuff and have more people that can be out there in the field,” he says. “Because it’s pretty hard to grow a business if you’re out in the field all day, every day. You can’t be focused on marketing and selling and meeting with clients, all that type of thing.”

And he knows to do that, you need to develop talent to take on the day-to-day tasks.

“Another personal goal is to develop a great team of salespeople, crew leaders and crew members. Developing this type of team will allow me to both achieve my professional goals as well as my personal goal of moving into a management position,” he wrote in his submission essay.

One takeaway from his college courses, which will help him as enters a management role, is how much networking plays an important role in business.

“I didn’t really realize how powerful that can before coming to school here,” he says.

As Collister gets closer to his graduation date, he’s going to take in all he can while at school.

“We have some pretty great professors, teaching all the courses that have had real world experience, whether that be through owning their business or working for other larger companies,” he says. “They’ve been here a long-time teaching this, so they really know the material.”

Since the 1970s energy crisis, screens have become an important part of environment control in greenhouses. More than a hundred types of fabrics have been developed for different purposes and all of them provide some energy conservation. They can be fully transparent to completely opaque, have open or closed weave, have reflective surfaces to reduce radiation or provide blackout conditions. Depending on the desired environment, selecting the right one can be difficult.

Comparing materials for energy conservation and other properties has also been difficult, as there have not been any standard tests available. In the past, most of the reported energy savings are from evaluating fuel savings in a particular greenhouse.

Recently, a standard in the Netherlands has been developed to provide uniform testing (NEN 2675 – 2018). Some of the properties that they examine include the following:

Energy savings – 30%-35% of total greenhouse heat energy is infrared thermal radiation. Energy screens reflect part of this heat (emissivity) from the surface. Screens also transmit radiation (transmissivity) through the fabric. The best screens are those that have a low emissivity and a low transmissivity. Screens with aluminized surfaces or aluminum strips meet this criteria and have the lowest radiation loses. Generally, if you install a single screen for energy conservation, select one with a closed weave and aluminum strips (Svensson – Tempa). This will provide shading during the day and energy conservation at night. Cracking the screen sections a few inches wide during the day will allow excess moisture to escape through roof vents.

Plant cooling: In hot climates, shading is important both for plant and air temperature control. In this situation, an open weave material works best (Svensson – Solaro, Polysack Plastic Industries – Aluminet). It allows the heat to rise and escape out through roof vents. It also allows the heat in the moisture to escape. The aluminum or white platic strips reflect the heat before it reaches the plant area. Depending on the amount of strips, it can provide moderate energy savings. An outdoor version of this material can be installed above the greenhouse to keep the heat from reaching inside.

Winter light transmission: To reduce heat loss during the daytime during the winter, a use of a material having a closed weave and high light transmission could be used (Svensson – Luxous). Materials with light transmission as high as 89% are available. Multiple screens of this material are sometimes installed to control the light level depending on the cloud cover.

Light Diffusion: Diffused light penetrates deeper and more uniformly into the lower plant leaf surfaces. It can increase growth and yield on most plants, especially tall ones, and is most effective on taller climbing crops, such as tomatoes, cucumbers and roses. Diffuse light can also reduce scorching, lower container temperature, reduce fungal spores and decrease insect propagation. Scattered light can also change the balance between red and far-red light. Alternating white and clear strips provides both energy conservation and uniform light across the growing area (Svensson – Harmony).

Blackout: To provide photoperiodic control for sensitive plants, a blackout material is needed ( Svensson – Obscura). It is available laminated with white surfaces on both sides to reflect summer heat away from the greenhouse and reflect supplemental light back to the crop area. With an inside aluminum surface, it will provide 70% energy savings.

Other considerations:

• Multiple screens are becoming popular to get maximum energy conservation. Cost is on average between $2 - $5/sq ft installed.
• Most screen materials are available in many shade levels and energy conservation percentages.
• A material that is flame retardant will meet most building codes.
• To reduce the shading when retracted, select a material that folds compactly.
• To be effective all screens should have a tight seal where they butt against the greenhouse wall and trusses.
• Useful life of the material is 5 – 10 years. System life varies up to 20 years.
• Clean dust and dirt to retain high light transmission, replace when it is frayed or aluminum delaminates.