When you’ve been farming long enough, you can feel it in your bones—when the corner of your house gets too warm or a cold draft sneaks in under the roll-ups. But as greenhouses grow more sophisticated and unpredictable weather becomes the norm, gut checks alone aren’t always enough.

This month in Field Notes, we’re digging into the five key principles of temperature control that can make or break your season.

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. Hot Zones and Cold Pockets: Why They Form

Temperature inconsistencies in a greenhouse usually stem from two culprits: poor airflow and air leaks (both in and out). Corners, endwalls, and areas near fans, doors, and roll-ups often become problem zones. Especially in structures without endwall vents or circulating fans, hot and cold pockets can form fast—and linger.

*** Pro Tip: Even in smaller tunnels, strategic placement of circulation or exhaust fans can keep air moving and temperatures more consistent.

. Airflow Beats Fan Size, Every Time

It’s easy to think a bigger exhaust fan will solve all your problems. But airflow isn’t just about CFM ratings—it’s about creating a clear path for air to travel.

We’ve seen better outcomes from a pair of well-placed 24” exhaust fans and opposing intake vents than from one oversized fan. Add automated controls—whether simple thermostats or more advanced controllers—and you’re no longer at the mercy of someone remembering to flip the switch when temps spike (or drop).

*** CT Greenhouse Tip: Our houses come standard with roll-up sides—but we also offer options like ridge vents and intake shutters that pair well with automation systems for even better results.

. Shade Cloth: A Simple Cooling Boost

Shade cloth isn’t just for midsummer lettuce. Used correctly, it can lower daytime temperatures inside your house by 5–10°F, reduce crop heat stress, and lessen dependency on constant fan use.

Shade cloth is typically installed using the same wirelock base on your hipboards and can be clipped or zigzagged into place easily. Whether you’re protecting tender greens, maxing out your tomato production, or keeping transplant trays from overheating, it’s one of the simplest and most cost-effective upgrades you can make for summer production.

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. Ridge Vents: Passive Cooling That Levels the Playing Field

When it comes to greenhouse cooling, ridge vents are the silent workhorses. By allowing hot air to escape naturally from the peak of your structure, they help bring inside temperatures much closer to outside conditions—often without touching a fan switch.

In the field, you’ll notice the difference immediately:

• Faster, more even ventilation
  
• Lower humidity buildup
  
• Better air quality for both plants and workers
  

Ridge vents work well across all tunnel sizes. The only drawback? Once you experience one, you’ll wish every house you own had them. And if the budget isn’t there on Day 1, no worries—all CT Greenhouse frames are ridge vent–ready, making it easy to add them later as your farm grows.

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. Blending Automation with Manual Tools

We get this question a lot: “Should I go all-in on automation?”
Short answer: not necessarily.

The best temperature control setups combine automation with smart manual systems. For example, automated ridge vents can manage your high points while manual roll-up sides give you flexibility and a fail-safe during unexpected power outages.

Our automation options give you powerful tools without a steep learning curve—think simple app-based control of vents, heaters, and roll-ups, alongside easy-to-set thermostats.

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The Real ROI of Stable Temperatures

Temperature control isn’t just about keeping plants happy—it’s about farm profitability. Stable greenhouse temps can:

• Extend your harvest window by weeks
  
• Improve transplant and propagation success
  
• Reduce pest and disease pressure
  
• Lower heating and cooling costs
  
• Help your team work more comfortably and efficiently
  

Each stable degree translates into earlier market sales, higher-quality crops, and stronger financial returns.

The Bottom Line: Know Your House, Then Build Smarter

At CT Greenhouse, we’ve built our own tunnels, walked our own rows, and tweaked our own ventilation setups more times than we can count. That’s why every house we design—from a simple 20’ wide grower kit to a fully automated Tomato Powerhouse—is built with airflow, temperature control, and real-world farming experience in mind.

Need help thinking through the right mix of tools for your tunnel?
Just give us a call or shoot us a message. We'll talk it through with you—no upsell, no pressure.

Let's grow smarter, together.
860-341-8707 | info@ctgreenhouse.com 

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