How to Spot, Stop, and Prevent Thrips in Your Greenhouse

September 11, 2026

Greenhouses are uniquely vulnerable to thrips. Stable temperatures let them breed year-round, continuous plant material gives them an endless food source, and limited natural enemies mean nothing keeps their numbers in check. With so many variables working against them, growers often underestimate how quickly a single overlooked thrips can spiral into a full-on infestation.

“Thrips’ morphology is very cryptic and difficult to detect,” says Muhammad “Zee” Ahmed, Ph.D., assistant professor of turf and ornamental entomology at Clemson University. “Let’s say thrips enter your greenhouse today. You’re not going to know for another two weeks, until they finish another generation and really start causing damage.”

That’s what makes proactive pest management critical—if growers can prevent one thrips from entering the greenhouse, they can avoid an infestation of 40,000.

Preventative Action Is Key

If growers are working with imported plant material from another greenhouse, they have no way of knowing what their risks are.

“Growers have to have the assumption that anything coming inside the greenhouse already has thrips,” says Samantha Willden, Ph.D., assistant professor of entomology at Cornell University. “That’s the safest way to get in front of prevention—just assuming the plant material isn’t clean.”

An effective scouting program will scout for bigger, more mature insects. But since most thrips species lay their eggs in the plant tissue, larvae are especially difficult to identify. So even if a plant looks clean, it could very well be infected.

For a free guide on successful thrips management, check out the OHP Thrips Cocktail. (pdf)

Here are Dr. Willden’s recommended actions for growers before they plant foreign plant material in their facility:

Dipping: Submerging plants in insecticidal soap or horticultural oils for unrooted cuttings or biopesticides. “This is a great way to reduce that incoming population and install your beneficial program,” she says.
Screening: Using mesh netting to block thrips from entering the greenhouse and affecting rooted crops. “Growers either love screening or they hate it because there is a direct tradeoff with airflow,” Dr. Willden explains.
Compartmentalization: Separating young plants from old plants in the greenhouse. “Your old plants will have thrips on them, and you want to keep the young ones clean,” she says. “Dip your new cuttings into the insecticidal soap and place them in a different area of your greenhouse—this helps prevent thrips movement between the plants.”

These tips can help growers prevent an infestation from happening in the first place. However, a thrips infestation can go undetected for weeks, likely longer if growers don’t know the warning signs to watch for.

Identifying the Warning Signs

Since they’re miniscule in size, identifying thrips is difficult for growers unless they place sticky cards around their facility. However, sticky cards will only catch mature thrips, which means they’ve already laid eggs.

“Sticky cards are useful for detecting the early arrival of thrips,” Dr. Willden says. “The larvae look similar, but it’s easy to identify the species of the adult thrips you’ll catch on sticky cards.”

If growers don’t have sticky cards and use their plants as indicators, the damage to the plant will be clear and specific to thrips.

“Thrips have a very distinct mouth that leaves scratch marks on the leaves of the plant,” Dr. Ahmed says. “They aren’t sucking the sap out of the leaf like other pests do. They’re scraping the plant before eating it.”

These scratch marks are also known as “silvering,” as the action scrapes the top part of the leaf back. When growers catch adult thrips on sticky cards and find silvering on the leaves of their plants, they’re almost certainly dealing with a thrips infestation. But not every infestation carries equal risk. How urgently a grower needs to respond ultimately depends on what they’re growing.

Considering the Susceptibility of Certain Crops

In a broad sense, thrips are polyphagous—meaning they feed on just about anything.

“They are a bigger pest compared to other insect pests because they don’t have a preference,” Dr. Ahmed says. “If there’s a crop, they will eat it, and they usually prefer ornamentals.”

For a free guide on successful thrips management, check out the OHP Thrips Cocktail. (pdf)

While no grower wants to see pests in their greenhouse, they’re an even bigger problem for ornamental plants. Garden center shoppers don’t want to see any visible damage to their crops. “They have a zero pest tolerance,” he adds. “If you’re buying a plant for your grandma or a family member and they see a small scratch on it, they’re probably not going to like it.”

Dr. Ahmed says thrips specifically target roses, hibiscus, and gardenias. While flower crops are susceptible to thrips, food crops aren’t entirely off the hook—their growers just have a little bit more leeway.

Dr. Willden works closely with tomato growers, and having a certain amount of pests is acceptable as long as their yields aren’t reduced and the fruit doesn’t have any major damage.

According to her, the biggest thing tomato growers should be concerned about is gold flecking, or patches of yellow that make the peel look dull, and depressions in the fruit, as thrips like to feed in protected areas.

“If two fruits are touching, thrips are likely to feed there,” she says. “They also like to feed in the depression where the stem meets the top of the fruit.”

If a grower spots the warning signs of thrips even after taking preventative action, they need to scout their greenhouse thoroughly.

Developing a Quality Scouting Program

When Dr. Ahmed’s students scout for thrips in the greenhouse, they follow a consistent three-step process:

Identify the hot spot. Pinpoint where thrips are entering the greenhouse first, since that’s where infestations typically take hold.
Increase scouting frequency. This is labor-intensive, but it matters. If growers don’t have the bandwidth for more frequent in-person checks, adding more sticky cards around the facility is a good substitute.
Determine the most effective pest management plan. Once thrips are identified, growers must decide if pesticides or biological controls are the right solution.

Dr. Willden offers a few additional tips for building a quality scouting program.

Invest in a microscope. A microscope will tell growers if they have thrips or another pest. It will also help them diagnose what kind of thrips they have so they can design their management plan more effectively.
Tap your plants. Growers can tap their plant over a white plate and see what comes off of it. This is an effective method for catching mature thrips.
Wash your plants. Growers take the plant tissue, shake it up in an alcohol solution, then pour it into a strainer with a coffee filter. This is an effective method for identifying thrips at every life stage.

Whether a grower is tending to ornamentals or food crops, the strategy stays the same: assume thrips are already present, scout consistently, and act before the population outpaces a greenhouse’s natural defenses. Dr. Ahmed and Dr. Willden agree that the growers who are best equipped to handle thrips don’t eliminate every risk factor, they catch the problem early enough for it to become manageable.

For more information on a great thrips products check out BotaniGard ES, Azatin O or Triact 70.

Fresh Off the Farm, Not Off the Truck: How KingsOne Farms Is Rethinking East Coast Lettuce

August 13, 2026

Lettuce production on the East Coast is much less common than the West Coast. A handful of growers have tried their hand at the crop, but the large majority of lettuce in the U.S. and Canada still comes from California and Arizona.

The distance doesn’t only drive-up transportation costs. It also pushes lettuce on the shelf closer to its expiration date, two major inconveniences for grocery store shoppers on the East Coast.

“By the time you get the lettuce, it was already on a truck for four days and sat on a grocery store shelf,” says Cole Mucci. “So a lot of people on the East Coast don’t know what it’s like to buy and eat fresh lettuce.”

That gap is what led Mucci, an Ontarian and Mucci Farms legacy, to launch KingsOne Farms: cleaner, high-quality head lettuce grown closer to the people who eat it.

“I always knew I wanted to be in the industry in some way,” Mucci says. “I wanted to differentiate myself by using new technology and homing in on food safety.”

KingsOne Farms is a 6.5-acre greenhouse facility located in Kingsville, Ontario. Production began in January 2026, with its lettuce marketed under Naked Leaf, a Mucci Farms brand. Mucci says the business is off to a strong start.

Putting Quality and Food Safety First

Since most lettuce in Canada isn’t grown locally, Mucci makes “Canadian grown” central to his marketing efforts.

Now, Canadian customers can purchase lettuce that was just harvested yesterday or two days prior, ensuring a fresher and more consistent high quality product throughout the year.

Mucci also grows without pesticides. He emphasizes that this focus on cleanliness is what differentiates his indoor-grown product from lettuce and leafy greens grown outdoors.

A Smooth Start

Launching KingsOne Farms has gone smoothly. As with any new facility, there are always challenges during startup, but Mucci says the team is extremely happy with the quality of the lettuce and proud of the people behind the operation.

“We’re extremely happy with where we are today,” Mucci says. “Like any startup, there have been challenges along the way, but we’ve been able to work through them. At the end of the day, the quality of the lettuce has been outstanding, and that’s what matters most.”

The standout right now is a Romaine variety that is selling extremely well. It’s crunchy, sweet, and has a long shelf life.

“Even just five to 10 years ago, I would say the lettuce varieties in greenhouses didn’t perform very well,” he says. “Now we’re doing a much better job of growing lettuce that has a good crunch and exceptional shelf life.”

Outdoor lettuce toughens up from wind and rain, while greenhouse lettuce has historically been softer. Mucci says advances in greenhouse technology, climate control and improved varieties now allow KingsOne to grow lettuce with quality crunch, sweetness, and shelf life.

Looking Ahead

Mucci points to three milestones from the last year: producing a clean, safe product; building a team that’s engaged and growing; and getting the facility running the way it should.

The last one is no small feat. Since ramping up production at the start of 2026, KingsOne now produces 250,000 heads of lettuce per week. While he’s not considered a large-scale grower just yet, Mucci plans to get there.

“I want to be a large-scale grower who grows the right way,” he says. “There are some companies out there that don’t put the plant first, and that’s something we’re 100% doing at KingsOne.”

That ambition runs into a real headwind. High-profile bankruptcies and heavy capital bets across controlled environment agriculture (CEA) have made some buyers cautious—that’s the real dividing line in CEA: who’s actually running the operation.

“I think it’s great that people are passionate about CEA,” he says. “Technology has moved the industry forward in a big way. But at the end of the day, it’s still farming. You can’t forget the fundamentals of farming, and unfortunately I think a lot of people do. The best operations are the ones that combine great technology with great growers.”

“At the end of the day, we’re farmers,” he adds.

No four days on a truck. No week-long expiration date. Just lettuce, grown a couple hours away from the people eating it.

For an excellent organic product used in today’s CEA operations, check out the OMRI-approved BotaniGard line of products from OHP.

How to Spot, Stop, and Prevent Spider Mites in Your Greenhouse

July 24, 2026

Since greenhouses remove the mortality factors that would suppress spider mites, growers are especially vulnerable to an infestation. These factors include predators, extreme temperatures, and volatile weather conditions.

“Greenhouses have suitable temperatures year-round and often ideal temperatures for the growth rate of insects,” says Laura Ingwell, Ph.D., associate professor of entomology at Purdue University. “Growers create a perfect mesocosm of a well-fed, ideal temperature food source that’s never being interrupted by predators or rain—spider mites flourish in that environment.”

Because growers control their environment so precisely, they often underestimate the conditions they create. There aren’t predators, temperature swings, or rain to keep spider mite populations in check.

Every grower could experience an infestation if they don’t take precautionary measures. Even if they do, they must know how to respond.

Considering a Greenhouse’s Vulnerability

The types of plants grown in a greenhouse have a direct correlation to spider mite infestations. This is true for both crop type and how long it’s been in the greenhouse.

“The longer a plant is in the greenhouse, the more likely it is to accumulate pests,” Dr. Ingwell says. “So your highest area of risk in the greenhouse is the older plants that are harboring mites.”

To reduce the risk of harbored mites spreading, Dr. Ingwell suggests considering the spatial organization of plants and the movement between older plants and plant starts. Movement especially, she says, is how pests tend to spread.

“Points of entry are usually going to be the origin of an infestation,” she explains. “So greenhouse growers should think strategically about the organization of their plants.”

Dr. Ingwell offers three specific recommendations for greenhouse growers:

Have protocols in place at the point of entry. This helps reduce the risk of workers bringing in a spider mite on their clothing, which is also known as a hitchhiker.
Consider how workers are moving through the greenhouse. Ensure your workers are going to the seedlings and young plants first, then go to the older plants last.
Be mindful of the crops you’re growing. While spider mites feed on thousands of host plants, there’s evidence that some crops are preferred and more likely to be colonized than others.

Growers cultivating susceptible crops should prioritize early detection and proactive prevention. That starts with knowing which crops are most at risk. To see how you can control spider mites check out this helpful guide.

Crops to Monitor Closely

Food crops are much more likely to attract spider mites, and it’s difficult to prevent them from entering the greenhouse altogether.

“Food crops have to be grown for a long time in a greenhouse for flowering and fruiting,” she explains. “I think cucumbers are at the top of the list for susceptible greenhouse crops. If you’re growing cucumbers in a greenhouse, you’re going to have spider mites.”

Cucumbers and tomatoes are especially vulnerable to mites because they’re vining crops that have thick leaves.

“They penetrate into the leaves of the plant, pulling the juices, photosynthesis, and sugars out of the plant material,” Dr. Ingwell says. “They don’t damage plant cells and they don’t leave holes in the leaf. Their mouth parts are very exact, and they can go in between cell layers to get the exact tissue they want to feed on.”

As time progresses and the spider mites continue to feed on the plant, chlorotic spots will start to appear due to the photosynthate loss in those cells. Experienced growers will notice those spots early on—but newer growers may not notice them until more severe warning signs emerge.
Knowing what to look for and when can be the difference between early intervention and a full infestation.

Spotting Signs of a Spider Mite Infestation

One of Dr. Ingwell’s biggest goals is teaching growers how to identify warning signs sooner. Here are the different infestation signs growers will encounter ranging from the least to most severe.

Spotted leaves. Distinct bleach spots on the leaves of the plant.
Mottled leaves. Larger bleach spots on the leaves that start to blend together—not distinct individual spots.
Webbing on leaves. When spider mite populations are high, webbing will be visible on the leaves of the plant. “Eventually, you will start to see spider mites crawling around on that plant material,” she adds.

To make sure they’re dealing with the two-spotted spider mite, she encourages growers to perform the “white paper test.” This test makes it easy to spot an infestation before the other signs start to appear.

“You hold a white piece of paper under the plant and tap it, which will dislodge the mites that are harbored in the plant,” she says. “Spider mites are almost translucent with two black dots on them. If you have mites, you’ll start to see little black dots crawling around on that sheet of paper.”

The faster a grower acts, the better their chance of containing it.

The Importance of Sanitation

Sanitation is the most effective weapon against a spider mite infestation.

“It’s really about starting with a clean environment,” she says. “That means having no weeds and clean benches in the greenhouse.”

This applies to plant material as well. Dr. Ingwell suggests finding a healthy seed source and ensuring the growing media entering the greenhouse is sterile and clean.

“That could mean physically inspecting all the plants that enter your facility,” she says. “It could also mean proactively releasing a predator to take care of anything that might be residing on those plants before you plant them in the greenhouse.”

But prevention doesn’t stop at planting in a clean greenhouse environment. Growers must maintain clean, sterile surroundings during and between growing cycles. This means removing all plant material from the greenhouse and cleaning as well as disinfecting all structures.

“If you can’t get a sanitizer on the surface, do a heavy hosing down,” Dr. Ingwell explains. “Dislodge them to the ground and wait as long as you can until planting again. This gives them time to starve.”

For Dr. Ingwell, preparedness is the bottom line.

“Growers have a balancing act of all the different things they have to manage in the greenhouse,” she explains. “They need to understand the biology of each potential pest they could encounter on their crops.”

In a greenhouse, the conditions are always right for spider mites. The question is whether a grower is ready for them.

One Engineer’s Fight for Energy Efficiency in CEA

July 15, 2026

Gretchen Schimelpfenig entered the energy space fighting climate change one utility bill at a time. As senior energy engineer at Energy Resources Integration, she aims to save energy and reduce the cost of operating buildings.

She originally started working on university buildings, data centers, and hospitals. Throughout those experiences she learned a lot about HVAC and lighting, which encouraged her to tackle the energy challenges plaguing the controlled environment agriculture (CEA) industry.

Since she first joined the industry in the 2010s, when CEA was picking up steam in the U.S., Schimelpfenig started creating policies and programs that aimed to make indoor agriculture more efficient.

“I didn’t realize how much energy was used in CEA until I started working in large-scale greenhouse construction,” Schimelpfenig says. “I wanted to look into how better HVAC and lighting solutions could keep that in check.”

This has been her primary focus for the last 10 years. In that time, she’s helped growers optimize their operations by making smarter energy-focused decisions.

Knowing What to Look For

When she first walks into a CEA facility to perform an energy audit, Schimelpfenig evaluates the organization, the control system, and the equipment installed.

Organization: Getting a feel for the facility’s overall health helps Schimelpfenig determine what the grower’s budget could be for improvements. “If it’s an older facility, for example, low-cost quick fixes that could make a big difference for them to keep equipment running efficiently,” she says.
Control system: How data is monitored and how many people are responsible for operating controls are also key. “Whether they use a tablet, central computer, or their phone, automation matters because it can save energy,” Schimelpfenig explains.
Equipment: Lastly, she looks at the unit heaters, boilers, lights, and other pieces of equipment that are high energy users. “I’ll look at the make and model to get an estimate of how much energy is being used by those systems,” she says. “Then I’ll go back to my desk and use that information to make some energy models to calculate potential savings.”

Once she completes her first walkthrough, Schimelpfenig addresses the most prominent energy opportunities in the operation.

Common Greenhouse Energy Opportunities

Here are the most common drivers behind energy costs that Schimelpfenig encounters across CEA operations:

High-pressure sodium (HPS) lights. Some growers still use HPS lights over LED lights, which can account for 75 – 90% of electricity bills for greenhouses.
Thermal Curtains. Growers may not use energy curtains or have ones that are outdated and in need of repair. By failing to use or upgrade them, they’re unknowingly driving up their energy costs. “The latest climate screens are a great way to save energy on heating,” she says. “Growers can tailor the environment for shade during the day and retain heat at night.”
Automation. Lighting controls are one of the main things Schimelpfenig focuses on when evaluating a CEA operation. Using sensors to automate supplemental lighting operation saves energy in every climate. “If growers are using timers for scheduled control, there is almost always savings if you move to a sensor-based system,” Schimelpfenig says.

While updating these parts of a CEA system is important, it can get expensive—and fast. For that reason, growers should take return on investment (ROI) into account before making any energy upgrades to make sure they tackle the right project first.

Taking ROI Into Account

The importance of ROI varies from operation to operation.

Larger greenhouse operations can tolerate longer payback periods, even if it takes seven to 10 years. However, that’s not the case for small growers with lower profit margin crops—they often need to see ROI within three to five years.

“When I do energy audits at greenhouses, I can usually get a sense of the payback period we’re talking about,” Schimelpfenig says. “If I see a lot of newer equipment, I might assume this facility has been able to do these replacements and they’re not deferring their maintenance.”

This indicates that the facility can schedule equipment replacements in advance instead of waiting for a failure to occur before replacing it.

For operations that can only afford to update their equipment when it’s absolutely necessary, Schimelpfenig encourages them to explore on-bill financing. This gives small-scale growers the option to pay energy upgrades off on their energy bill instead of putting capital into it.

“Some folks need loans, and they can’t make ROI work without one,” she explains. “This year, I’m looking at projects that have shorter payback periods because the cost of energy is only going up.”

Energy Efficiency in Action

Since 2024, Schimelpfenig has worked on a large energy efficiency greenhouse project in Idaho. Setting May 2026 as a completion date, the project will cost approximately $1.8 million. But, since it was built with energy efficiency in mind, it will receive about $200,000 in rebates.

Those rebates have helped shorten the payback period.

“My work is quantifying those energy savings because of the measures we took,” she says. “That’s what energy engineering comes down to sometimes—being the translator for energy upgrades, proving to the utility that they work, and making sure the grower gets the support they need to do the efficient thing.”

She set out to fight climate change one bill at a time. Ten years in, she’s still at it, and continues to make a difference with every grower she works with.

The Intersection of Horticulture, Hospitality, and the Culinary Arts

June 17, 2026

Jack Maruna has spent the last four years at the intersection of horticulture, hospitality, and the culinary arts. He dedicated most of that time to Auburn University’s Food U program, a campus-wide effort that brings locally grown food to students across campus.

Jack Maruna

He brought knowledge from that experience to his new role at Jones Valley Teaching Farm as the director of partnerships just a few months ago.

Similar to Food U, Jones Valley Teaching Farm is focused on education in the horticulture and culinary hospitality realm—just at the K-12 level. The nonprofit works directly with 16 schools across Alabama, though its level of involvement differs depending on how much help each one needs.

Understanding the Program Levels

Here’s a breakdown of Jones Valley’s different levels of involvement in Alabama schools.

Level 1: Hiring an instructor at a school. Jones Valley chooses the horticulture program instructor at the greenhouse, outdoor teaching farm, and culinary lab—it pays their salary, and they teach the lessons developed in house. “That’s the most intimate level of involvement,” Maruna says. “Often we are financing the design, materials, and construction of outdoor, indoor, and greenhouse teaching labs.”
Level 2: Co-developing an ag or culinary program with the school. The second level typically involves redeveloping the current curriculum. “We essentially help schools revamp their program,” he says. “Or they have an old, dilapidated greenhouse that we help them get back up to speed.”
Level 3: Finalizing details. The last level is the least involved of the three—Jones Valley refines the horticulture and culinary curriculum, ensuring it’s up to date. “We hone in on the specific, more granular details for the curriculum we’re assisting them in,” Maruna explains. “We’ll go into a greenhouse, recommend equipment, and make sure it fits into the current curriculum.”

But for Maruna, the levels are just the delivery mechanism. The real test is whether what’s being taught can keep pace with where the industry is actually going.

During his time in academia, Maruna discovered that universities could be up to three to five years behind private industry. “That defeats the purpose for me,” he explains. “What are we researching at university if growers are already ahead?”

Maruna sees similar risk in K-12 programs. If the curriculum isn’t closely tied to where the industry is headed, schools fall behind before the students graduate. That’s the main challenge he aims to address at Jones Valley Teaching Farm.

But staying ahead of industry trends only matters if kids are engaging with food in the first place. That fundamental connection is where Jones Valley’s mission really begins.

The Jones Valley Mission

One of Jones Valley’s most ambitious goals is to reconnect children with locally grown food.

“It’s a disservice if you go through grades K through 12 without ever talking about food,” Maruna says. “Then, you enter your adult life not understanding where our food is coming from and how.”

From there, it’s a trickle-down effect on health and making informed decisions about food. About 64% of the U.S. eats three meals per day. It’s very likely, Maruna says, that a majority of those people don’t think about those three meals or how they reached a dinner plate.

“It takes a lot of hands, states crossed, logistics, and trucking to get to the final consumer,” he explains. “When people always have food available to them and lack perspective for how it got to them, they take it for granted.”

The hands-on programming Jones Valley offers has already started making a meaningful difference. In one school that has both culinary and horticulture programs, the organization went through an entire lesson with cucumbers. Students grew cucumbers in a Dutch bucket system, harvested them, then pickled and canned them.

In Maruna’s words, the kids were obsessed with the finished product.

“Kids can’t believe that seeds turn into pickles. When they get into a program like this, they’ll be walking around with a foot-long cucumber eating it raw and loving it,” he says. “That connection afforded them the ability to try it, and I think they love it because they were intimately involved in the process.”

Introducing children to these concepts when they’re young opens their eyes to a future career path.

Planting the Seed Early

Jones Valley offers a two-year internship for high school juniors and seniors. It’s a personal and professional development internship, aiming to give these students direction after they graduate.

“The goal isn’t simply to create farmers. It’s to expose students to the entire food system, from production and distribution to culinary arts, business, education, and environmental careers,” he explains. “This is a human impact opportunity, we see leaders exiting our program no matter what next step they decide to take after high school.”

The program currently has 10 interns. That may seem like a small number, but the impact these 10 people can make is significant.

“You think about 10 interns and it doesn’t sound like a lot,” Maruna says. “But when they all graduate from an internship program and stay in the industry year over year, it ends up being pretty impactful for the state of Alabama.”

Jones Valley’s goal: growing that number from 10 to 50 within the next five years.