Keeping the greenhouse well maintained heading into Autumn

As the growing season transitions from summer to fall, many greenhouse operators focus on crop cycles and climate controls, but the infrastructure itself demands attention, too. Mid-season maintenance isn't just about keeping systems running through the next month; it's a key strategy for long-term performance, energy efficiency, and avoiding expensive failures down the road.

Anthony Hill, LLK's National Project Lead, broke down what facilities should prioritize during this transitional window.

From vent actuators to roof panels, Hill's on-the-ground perspective offers a clear checklist for facility managers and growers aiming to stay ahead of seasonal stress.

​​Structural and mechanical priorities for the fall transition
Ventilation systems: Ventilation systems are the lungs of the greenhouse, and their rack and pinion mechanisms are often underappreciated. These components endure heavy wear during summer and are crucial for air exchange as the environment shifts toward cooler, more humid conditions.

"I'd say probably the most overlooked one is rack and pinions on the ventilation systems," Hill explains. These systems can be easy to ignore if they're automated, but noise buildup and mechanical fatigue are early signs of stress. "You'll really start to hear the noise in progress."

Early maintenance — checking for misalignment, lubrication, and wear — can extend the life of the components and reduce the likelihood of mechanical failure just when you need precise climate control.

Shade systems: Shade systems are pushed to their limits in summer. As they transition into fall, it's critical to inspect both the fabric and the drive system. Hill notes that many of these systems run on rack and pinion or cable-driven assemblies similar to ridge vents.

"If you notice the cloth begins to tear, then you know it's time to get new curtains." This can be caused by constant movement from fans or sun exposure. Mechanically, the earliest warning signs are often audible: "If you have a push-pull system… you can see the teeth on some of these start to wear down."

Regular lubrication, proper fabric tension, and checking for misaligned cables or worn-out clips all contribute to a longer lifespan and fewer operational hiccups when seasonal shading is still required but used less frequently.

Roof glazing: Your glazing system bears the brunt of weather transitions. Leaks, expansion stress, and material fatigue all tend to surface as summer heat gives way to cooler, wetter conditions.

For glass greenhouses, leaks typically begin beneath the bar caps: "What you want to do is have a constant eye on what's going on underneath the bar cap of your glazing system — that would be the sealant."

In polycarbonate systems, UV degradation and micro-cracks can develop invisibly. Poly film greenhouses require blower motors to maintain inflation. "If inflation is not proper, then the life of your poly is going to go down every year."

Visual inspection, sealant testing, and getting hands-on — sometimes literally — are essential for diagnosing issues before they result in crop stress or structural damage.

Sealant diagnostics: There's more than one type of sealant at work in a greenhouse envelope, and knowing their failure signs helps target repairs effectively.

"Those dark spots in the silicone indicate it's time to remove and replace the sealant," Hill says. "Underneath the bar cap in a glass case, you'll typically find a butyl sealant, and once it dries and begins to crack, it tends to chip off and become dusty."

Bedding putty, found under the glass itself, may be visible from the inside if improperly installed or degraded. Proper inspection involves viewing seals both inside and out to catch breakdowns early.

Vent actuation: As cooling needs decline and vents begin closing more often, the reliability of vent actuators becomes critical. Limit switches are a known failure point. "Most of the time, those are the first to go," Hill says.

Mechanical linkages like couplers and motor hangers also require close inspection. These parts bear the brunt of torque and motion and are prone to cracking or loosening over time. "Those ones will get the most weight bearing."

Failure to act on these wear points can lead to vent binding, which in turn compromises climate control — and often requires costly mid-season repairs.

Condensate and humidity: Condensate management becomes particularly important as greenhouse humidity levels climb in the fall. Misting systems play a dual role: maintaining plant hydration and helping regulate internal microclimates. But their performance hinges on microscopic components.

"Filters can go unnoticed because they're so small," Hill warns. "Changing those out once a year is crucial."

Operators should also monitor for environmental indicators like fogging or air stratification. These may point to underperforming vents, clogged screens, or faulty HAF fans — all of which compromise airflow.

Evaporative cooling pads: Evaporative cooling systems are mission-critical in many facilities, especially during the lingering heat of early fall. Yet, the pads and troughs are frequently neglected.

"Inspecting and cleaning the pads and cleaning the gutter trowel in the evaporative system is crucial," Hill advises. Pads clogged with algae or debris not only reduce cooling efficiency but can also introduce mold and mildew into the air stream, affecting crops and equipment alike.

Case studies: When maintenance made the difference
Hill's team recently worked with a facility in West Lafayette, Indiana, where poorly aligned hangers caused rack and pinion binding. "Every single one of them was off by a couple of inches." The result was motor strain and limited vent movement. Once resolved, cleaning the insect screens added further benefits: "Immediate temperature change in there within a day."

At Kent State, a retrofit from failing 1940s glass to polycarbonate improved both safety and climate control. "Those tropical plants thrive better than ever," Hill notes, citing improved insulation and lighter loads on drive motors.

These examples underscore how routine inspection and retrofit work can dramatically boost operational performance.

What makes a greenhouse age well?
The difference between a high-performing greenhouse and one that deteriorates prematurely often comes down to attention to detail.

"The first thing that I'm looking at when I arrive at the facility is your rack, pinions, and hangers. If I don't see any grease marks, chances are that's the root of the problem."

Beyond mechanical systems, roof cleanliness is an immediate visual cue. "It definitely starts up top," Hill explains. Facilities that prioritize routine, preventative maintenance will see fewer breakdowns, lower energy costs, and a much longer ROI horizon.