Keeping Your Greenhouse Cool All Summer Long

By: Trevor Dueck for BC Greenhouse Builders

Summer in the greenhouse is a bit of a paradox. The long days and warm nights are exactly what your plants have been waiting for, but push the temperature too far, and that cozy growing space can turn into a sauna! The good news is, with a few smart habits and the right tools, you can keep things comfortable for you and your plants all season long.

Why Summer Gets Tricky

Greenhouses are built to trap heat. That's the whole idea. But in the summer months, that same feature can work against you fast. On a hot day, temperatures inside can spike well beyond what's happening outside, stressing your plants and making it harder to manage humidity. The best thing is, with a little preparation, you have a season that can be very rewarding.

Start with Airflow

The single best thing you can do is move air. Open your vents and doors early in the morning before the heat builds and let hot air escape throughout the day. If you've got exhaust fans or louvered vents, run them, especially on still days when there's no natural breeze to help.

Automatic vent openers are worth their weight in gold here. They use a simple wax-filled cylinder that expands with heat to open the vent and contracts to close it. There's no electricity, no timers, no forgetting. Every BC Greenhouse comes with these included as standard, and once you've used one, you'll wonder how you managed without it.

Shade and Cool

If airflow alone isn't enough, shade cloth is your next move. It's easy to install, customizable for your greenhouse size, and can drop your internal temperature on the hottest days. For dry climates, a misting system can also help. It'll cool the air through evaporation and add humidity at the same time.

Water Smart, Not Just More

Hot weather means faster evaporation and plants that are thirstier than usual. The key is to water deeply and at the right time. Early morning watering gives moisture a chance to soak in before the heat sets in. Drip irrigation is ideal. It'll deliver water right to the roots with minimal waste, and mulching your containers and raised beds helps lock that moisture in.

Keep humidity on your radar too. A simple hygrometer lets you track levels in real time so you can catch any mold or mildew risk before it becomes a problem.

Grow What Loves the Heat

Summer's prime time for warm-weather crops. Tomatoes, peppers, eggplant, and melons were practically made for greenhouse growing in these conditions. They love consistent warmth and long days. If you're also growing herbs or leafy greens, tuck them into the cooler corners of your greenhouse or use shade cloth to slow bolting. Or save them for spring and fall when conditions suit them better.

Don't Skip Maintenance

A little upkeep goes a long way in summer. Clean your vents and fan blades regularly since dust and debris can build up fast and reduce airflow. Check door seals and glazing for any gaps that could affect your temperature control. Run your irrigation system to make sure there aren't any clogs or leaks. These small checks, done weekly, can save you from a bigger headache when the heat peaks.

If you're in a storm-prone area, take a few extra minutes to secure your vents before severe weather hits and make sure your greenhouse is sitting on a proper foundation. It's also worth documenting your greenhouse's condition at the start of the season, handy if you ever need to reference a warranty or insurance claim later.

Enjoy the Season

Most of all, enjoy yourself. Summer greenhouse growing, done right, is genuinely one of the best things about owning a greenhouse. The harvests are bigger, the days are longer, and there's nothing quite like stepping into a space full of thriving plants you've been tending since spring. A bit of planning up front means less stress and more success!

At BC Greenhouse Builders, we've been helping growers make the most of every season for over 75 years. If you'd like to learn more about our greenhouses or get advice for your setup, we'd love to hear from you. Visit us at bcgreenhouses.com to explore our full lineup and connect with our team.

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