Atlas Manufacturing greenhouse sales rep Stuart Sumner says interest in new structures has never been higher. “We have customers in various sectors of this industry that had very productive years despite COVID-19,” he says. “Due to this, we are seeing more interest and enthusiasm heading into 2021.”

According to Sumner, the following five trends in greenhouse structure innovation seem to be popping up more and more across the projects he has worked recently:

1. Positive pressure (PP) ventilation cooling — Produce growers are taking a closer look at PP ventilation systems, especially in hot and humid climates where a traditional system that draws more humidity from outside is not ideal, Sumner says. “When growing in a high humidity climate, adding additional humidity through an evaporative cooling system in a negative pressure setting can have a detrimental effect on crops,” he says. “You will be much more likely to experience issues with fungal pathogens and have a greater need for humidity control equipment.”
2. Supplemental lighting — Sumner answers a lot of questions about supplemental lighting during the design phase. “There is a lot more interest surrounding LED options for supplemental lighting and the technology itself is rapidly evolving,” Sumner says. “Companies are constantly innovating these lights to be more energy efficient and effective at targeting the desired spectral wavelengths of PAR light. The traditional HPS fixtures may be the most commonly used at this time, but I believe the LEDs may overtake them as the most frequently used at some point in the future.”
3. Taking sidewall height even higher — Growers are also interested in installing the highest sidewalls structurally-possible in new builds, Sumner says. This strategy allows for a larger area at the top of the structure to push and store hot, humid air far away from the plant canopy down below, he says. “It’s true that the higher you can go [on sidewalls], the more optimal situation you are in from a ventilation and cooling perspective,” Sumner says. “With everyone wanting to get those sidewalls as high as they can be, I like to joke that by 2050 we’ll all be growing crops in skyscrapers.”
4. Hydroponic grow systems — From the ubiquitous “Dutch” bucket style for peppers and tomatoes to the popular vertical farming and deep-water culture growing systems, grower interest in replacing soil with growing media and oxygenated water has never been higher. “We are seeing commercial growers utilizing hydroponic grow systems such as Nutrient Film Technique (NFT) systems that can reduce the expected harvest time considerably when compared to more traditional grow methods. I believe we will begin to see this system become more popular as we move forward.”
5. Insect exclusion structures — Companies like Atlas are recommending growers, regardless of crop, consider built-in insect protection measures. Sumner refers to these design add-ons as “insect exclusion structures.” Extending the frame of the greenhouse out on opposite ends a set distance, and then covering that area between the ventilation equipment and the outside with woven insect proof materials helps prevent insect intrusions from the cool outside air. “This is something that we really think is worth a grower’s investment in the long term. It will save you money,” he says.

What is your current view of consumer trends related to indoor production of fresh vegetables for the U.S. market?

We’ve got an increasingly diverse population, whether it’s coming from [inside or outside] the U.S. The beauty of that is it brings with it diverse cultural practices and diverse food tastes. Even more recently, there’s [been] concern not only for human health but also for pet health. That’s all driven by a culture that is intensely interested in what goes into [food] products. We have today an “experience hungry consumer market.” Anything around that experience drives a lot of these trends. That causes growers to think about what markets they want to participate in and those things elevate growers to try new types of crops. It causes breeders to push their breeding results and types of offerings in these specialty crop markets to a higher level, because consumers are not only interested in what foods are available, but where they come from and who’s growing them.

What range of pest management practices are available in the market today to help growers achieve the highest quality in their indoor-grown vegetable crops?

It’s certainly been a rapidly changing environment, especially with new technologies being driven under this new acronym of CEA, which is controlled-environment agriculture. These growers have the ability to control their environment, which means they can control temperature, light, water, nutrients and the use of crop protection products to manage diseases and insect pests. Traditional crop protection chemistries and new biological systems that have come into play now in the last several years — they’re all formulated and labeled for indoor growing in these controlled-environment agriculture systems. Those are the types of things that we see today that are available for growers that BASF is clearly a part of now.

What role do biologically based pest management products and programs play in indoor production systems of the fresh vegetable market?

The challenge for growers today is that they’re being asked a lot of questions [about] how they do it and what’s in the products that they offer so that either the retailer, distributor or consuming public has a level of confidence that the grower is providing them with safe food. We have to find a way to bring biologically oriented approaches [together] with conventional chemistry so that if the grower has to use chemistry, then that chemistry help[s] them with the problem, but at the same time, [doesn’t] negatively impact the other biologically oriented approaches that they’re utilizing as a part of their pest management practices.

How is BASF working to bring new pest management solutions that help growers meet these changing consumer trends?

There is an ongoing need for education and training. That really is at the heart of the demand for commercial growers today — trying to understand how to bring all of this together under these more complex, diverse pest management systems we have. What we have done in the recent past is not only have we been able to be a more reliable commercial provider of these beneficial nematodes — we’ve introduced some new chemistries, particularly for insect and mite control, that were formulated and developed carefully to be compatible with beneficial insect systems.

Looking ahead, what can professional growers in these indoor vegetable production systems expect to see from BASF in the next 3-5 years?

BASF is investing, every day and every week and every year, research and development monies into new chemistries and new innovations that are planned out over the next [10 to 30] years and beyond. Even in this short term of three to five years, there are some new innovations and new chemistries that we’ll bring into the marketplace — most likely in [the] insecticide space, because we know that’s where there’s probably the greatest need to manage resistance issues. We’re encouraging our internal development efforts to look at formulations that can be utilized more effectively, certainly with the idea that less is more — not only [if it] can be used at a lower rate, but if it can also be even more specialized and targeted for certain pests [and diseases].

What is the greatest challenge when producing food or other consumables?

From the perspective of the growing mix, food safety is an aspect that has become more and more important. Berger is ISO 9001-certified, which means quality control is extremely important to us. With growing media being increasingly used for a wide variety of consumables, Berger has been very pro-active when addressing these markets and has tried to stay ahead of the curve by rapidly implementing a food safety program. This led us to adding new equipment and procedures in order to address the growing demand for products that are safe for food production.

What else can be done to prevent potential contaminations?

It’s all about monitoring and rigorous testing in key areas of our operations implemented through our quality control program. We have analyzed all our processes to determine what we need to test for and where we need to pull samples. We also monitor our entire supply chain for common food safety indicators (total coliforms, fecal coliforms, E. coli, …) and have implemented additional security measures to further reduce the risks of contaminations throughout the manufacturing process.

How can using a quality substrate help growers address this challenge?

You want your mix to work for you, not against you. If the physical or chemical characteristics of your mix aren’t adjusted correctly or are uneven, you can encounter major problems. Any time spent correcting these issues is not spent managing other important aspects of operations. Moreover, if these issues cannot be corrected and lead to a significant reduction in sellable produce, the economical impact can be consequential. Using a substrate from a reputable supplier with a solid quality control program like Berger will ensure you get uniform and predictable results.

When producing young plants, what are the characteristics you look for in a growing media?

This is a critical step as seedlings are very susceptible to diseases. Growers want a substrate that allows them to develop strong root balls which maximizes transplant success. The fertilizer starter charge should be well balanced, but low enough to prevent stretching. The growing mix should have a finer particle size since you want to maintain a uniform moisture around the seed throughout the germination process. However, too much moisture can also be problematic. Fine or coarse grade perlite can be added to give additional drainage. Recent research we have done with fine grade wood fiber has shown tremendous results and has led to the creation of our new BM2 NF Wood products. The combination of fine grade peat moss and wood fiber promotes phenomenal root development and helps produce stalky transplantable seedlings.

Does Berger offer any additional services to customers that produce food?

A final inspection report is available for each bale or bag of mix we deliver. Upon request, we can offer additional assurance by providing a third-party food safety analysis report specific to the product a customer received. The tolerance levels are determined with our customers as there currently aren’t any industry accepted standards for growing media. Moreover, our grower advisors are available to support our customers in all aspects of their operation. Whether related to food production, selecting the right growing media or any other part of the operation, our technical services team is available.

For more information:
Pierre-Marc de Champlain
Director of Technical Services
pmarcd@berger.ca
berger.ca

An experiment out of Wageningen University & Research in the Netherlands has shown that there may be some more efficient options in supplemental lighting for growers to consider.

Comparing the traditional high-pressure sodium lights often used as supplemental lighting in greenhouses with a broad-spectrum white LED light, the university found that tomato crops have the same, or higher, yields under LED lights.

Dr. Ep Heuvelink, associate professor at Wageningen, says the university was interested in comparing HPS lighting with white LEDs as more and more growers use supplementary lighting in their operations. Researchers set out to observe the role of the different wavelengths in the spectrum on crop development and crop physiology.

“For tomatoes, we’re talking about hundreds of hectares with supplementary light, and the norm is the high-pressure sodium lamp,” he says. “But everybody knows that LED is more electrically efficient than the high-pressure sodium lamps.”

Wageningen was particularly interested in the effects of broad-spectrum white LED lights because most growers using LEDs opt for 95% red lighting with a small amount of blue. “And that is not because that’s the best for the plant, but it’s because of economic reasons — because they’re LEDs, they’re most efficient in turning electricity into light,” he says.

Shedding some light

At the end of the experiment, Wageningen researchers found an 11% higher yield in the Tomagino cultivar and a somewhat higher yield in the Malice cultivar, although Heuvelink says it was not a statistically significant increase.

The study also included a look at lighting effect on brix levels, finding no differences between the two types of lighting when it comes to fruit sugar content. And while the experiment did not particularly look into quality issues like acidity or shelf life, Heuvelink says researchers didn’t observe any external quality differences.

But be aware of the investment costs as they can vary greatly, he notes.

Photo © warloka79 I adobe stock

Michigan State University Professor and Extension Specialist Erik Runkle and Assistant Professor Roberto Lopez collaborated with Greenhouse Lighting and Systems Engineering (GLASE) to discuss supplemental lighting management techniques. Here are some of their findings:

Stages 1 to 2: Stick to callus formation — For stage one, “you want to try to target a DLI of anywhere from 4 to 7 moles during this time period,” Lopez says. “Also, it’s very important to note that you want to provide indirect or diffused lights. This is primarily from the sun by utilizing shade curtains or white watts to maintain a photosynthetic photon flux density (PPFD) of anywhere between 120 to 200 micromoles.”

Stage 3: Root development — Stage three calls for increased light intensity. If growers are providing 70 to 120 micromoles of light with a target of anywhere from 8 to 12 moles per day, once those roots have initiated, Lopez advised to increase PPFD to between 200 and 400 micromoles.

Stage 4: Toning — In this stage, growers are preparing to tone liners for shipping or transplanting. Using 70 to 120 micromoles of supplemental lighting and maintaining a DLI greater than 12 moles of light is recommended.

“In some parts of the country, it’s going to be very difficult to maintain 12 moles of light because even with supplemental lighting, you may only be able to achieve 10,” Lopez says. “But as we tell most growers, the higher that DLI, the higher quality of crop you’re going to be able to produce and the faster you’ll be able to get that crop out of the greenhouse.”

At this point, growers can increase light intensity anywhere from 500 to 800 micromoles.

Supplemental lighting during plug production

To achieve a DLI of 8 to 12 moles, previous MSU research recommends providing 70 to 90 micromoles of supplemental lighting during stages three and four.

“We find that when you provide supplemental lighting for plugs, you’re going to reduce the production time of those plugs, you’re going to see an increase in stem diameter, which is going to produce a studier plug, and more branching,” Lopez says. “Oftentimes when these young plants are grown under high-pressure sodium lamps, because of the additional heat, you’re going to see that these young plants can also flower earlier upon transplant.”

HPS or LEDs?

“It’s very situational,” Runkle says, noting the final answer is often contingent upon many variables such as available electricity, cost to purchase and install, cost of electricity, hours of operation, lamp efficacy, fixture longevity and maintenance, light spectrum, uniformity and intensity. It is also noted that plants under HPS are typically 2 to 3° F warmer than under LEDs.

photos courtesy of charlie garcia and roberto lopez

High-quality vegetable transplants for high-wire production are defined as having thick and straight stems, compact growth with short internodes, well-developed and deep-green leaves, and shortened production times. A minimum daily light integral (DLI) of 13 mol·m^–2·d^–1 or greater is required to achieve these desirable morphological traits.

However, in greenhouses located in northern latitudes, the DLI can average between 1 to 5 mol·m^–2·d^–1 during winter months. Under these low light intensities, plants have weak stems and large leaves, are leggy, flowers are aborted, and subsequently, fruit abortion can occur leading to economic losses.

Supplemental lighting is commonly used to increase the DLI within vegetable transplant greenhouses during light limited times of the year. High-pressure sodium (HPS) lamps have been the industry standard for greenhouse supplemental lighting. However, the availability of energy-efficient light-emitting diode (LED) fixtures for horticultural applications are a promising alternative.

What they found

Beyond reducing the time to produce a high-quality vegetable transplant, the radiation quality (color) of LED supplemental lighting influenced the morphology and physiology of high-wire vegetable transplants when the natural DLI was low (=7 mol·m^–2·d^–1).

From previous MSU research we have concluded that LED supplemental lighting must contribute to greater than 40% of the total DLI to elicit morphological responses. Given this, supplemental lighting radiation quality could be used to elicit desired high-wire vegetable transplant morphological features as they can differ depending on the intended use.

For instance, seedlings can be used as rootstocks, scions, or as non-grafted transplants. Grafted seedlings benefit from an extended hypocotyl [the part of the stem beneath the seed leaves (cotyledons) and directly above the root] length, since it helps to increase grafting success and hence survival rate, and reduce rooting from the scion after transplant. However, elongated hypocotyls are not desired for non-grafted seedlings, as it can lead to weak transplants and logistical challenges for shipping.

Thus, a grower producing non-grafted transplants might utilize supplemental lighting providing B₂₅R₉₅ radiation as tomatoes, peppers and cucumber were the most compact under this treatment. However, they should also consider that parameters such as leaf area and fresh weight were negatively impacted under B₂₅R₉₅ radiation.

Lastly, we have also determined that LED supplemental lighting providing B₃₀G₃₀R₆₀ radiation produces comparable quality high-wire transplants to those grown under HPS lamps. Therefore, we can conclude that LED supplemental lighting is an alternative to the current industry standard for high-wire transplant production.