Keep Your Greenhouse Cool In Summer

Keep Your Greenhouse Cool In Summer

7 Ways to Cool Your Growing Dome

You can keep your greenhouse cool…even in the heat of summer.

A greenhouse is designed to trap heat. They are bound to get hot, but you don’t want them to get too hot. What is too hot for a greenhouse?

How does our 33′ Growing Dome® read 90° inside when the thermometer reads 90° outside?

Udgar is here to show you 7 Methods to Keep Your Greenhouse Cool

First – utilize Large Leaved Plants in strategic places…

such as these fig trees,keep your greenhouse cool or this grape vine. keep your greenhouse coolThey are both edible, fruit bearing, soil shading, evaporative coolers.

The large leaves help shade the soil and keep the soil cool. In this particular 33′ Growing Dome, we have about 40 tons of soil.

If that 40 tons of soil reaches 110° or 120° because it’s bare dirt, this dome would be a lot lot hotter than if we have 40 tons of soil at 75° or 80°.

Also, plants themselves act as evaporative coolers.

They transpire moisture through their leaves, which helps keep your greenhouse cool.

Second – The Water Tank

We talk a lot about how the water tank helps keep the dome warm in the winter. It also helps keep the dome cool in the Summer.keep your greenhouse coolThe water tank contains 3,000 gallons of water which is cooler than the ambient temperature.

Temperature exchange happens easily through the sheet metal framing of the tank. The temperature outside could be 90°, trying to climb to over 100°, but the thermal mass of the 75° water keeps the dome cool.

Air Flow, Fans, and Pistons

Third – Fans

Here is an example of a 110 volt fan in our 33′ Growing Dome which helps move air. We also use

direct drive cooling fans run from solar panels.keep your greenhouse cool

Free e-book 9 Reasons a Growing Dome is Better Than a Regular Greenhouse

The Game Changing Greenhouse

Click here to access the 9 Reasons e-book

Fourth – Automatic Vent Openers

Here is a shot of the upper vents…keep your greenhouse coolhere are the lower vents.keep your greenhouse coolThe vents automatically open when it gets hot. The piston is filled with wax. When it gets hot – it expands – and opens the window.

The Growing Dome naturally creates a convection system when the hot air escapes from the top and gets replaced by cooler air from the bottom vents.

Fifth – Shade Clothkeep your greenhouse cool

A shade cloth cuts down the brightness of the sun and the heat. You can hang them on the inside or put them on the outside.

However, if it is a dark colored shade cloth, it will get hot, and you can actually increase the temperature.

This particular shade cloth is called aluminet. It’s made of aluminum and it doesn’t heat inside of the Growing Dome.

We recommend a 50 percent shading.

Do not cover the whole of the dome. You don’t want to have too much shade and make the plants leggy.

With the shade cloth hung on the south side, you cut down the midday sun, but still get early morning and late afternoon sun.

Sixth – Undersoil Fan/Climate Control System

The undersoil fan is driven direct drive by a solar panel. It blows hot air through pipes buried in the soil – effectively cooling the air as it cycles through the dome.keep your greenhouse cool9

keep your greenhouse coolSince we have shaded soil at 75°, and 95° air blowing through the soil….

….the air comes out at 85°.

So we’re actually cooling the dome by blowing hot air through pipes buried in the soil.

Free e-book 9 Reasons a Growing Dome is Better Than a Regular Greenhouse

The Game Changing Greenhouse

Click here to access the 9 Reasons e-book

Seventh – Power of Evaporating Water

The power of moisture, and evaporating water, creates a cooling effect of up to 20°. There’s two ways we do this in the dome.

One way is a swamp cooler.

Here Udgar explains the use of our solar powered swamp cooler. It is very effective for keeping the dome cool…up to 20° cooler while it is running.keep your greenhouse coolThe swamp cooler blows air through a pad which is kept moist by water trickling down or being sucked up the pad.

The cooling pad is designed to let air flow through it.

The fan on this particular swamp cooler is driven by a solar panel. There’s a little pump which pumps water through the cooling pad on the outside and the air coming out is around 70°.

The second way we use the power of evaporating water is a Misting System.

Misting systems can be set on various types of timers or humidistat controllers. The light spray of water is effective at cooling the space, but use it judiciously to avoid too much moisture leading to mold or fungus.keep your greenhouse coolWell, it’s hot. It’s summer. It’s hot outside.

If you have a greenhouse, or a Growing Dome…

….you can bet it’s going to be hot in there too.

Learn how to keep an accurate track on the temperature. Don’t keep your thermometer in direct sunlight or propped up under a black pot!

Learn hot to “listen” to your plants. They will tell you if it is too hot inside your greenhouse.

The 7 Methods to Keep Your Greenhouse Cool

  • Plants – large leaved strategically placed
  • Fans
  • Automatic Vent Openers
  • Water Tank
  • Undersoil System/Climate Control System
  • Swamp Cooler
  • Misting System

These are all ways we have been able to keep our Growing Domes within an ideal temperature range – even in the middle of the hot summer.



  1. We built a cob retaining wall 3 feet in from the edge of the 22ft dome. It is 3.5feet high. Unfortunately it absorbs heat and consequently the soil bakes and takes forever to reabsorb. I’ve considered painting it white to reflect the heat? Any suggestions? Thanks

    • Hey Larkin,

      I would not paint the wall white. I think you will want that heat sink come winter. I wonder about draping a relfective material over the wall for the summer season?

      Furthermore, I would make sure to have plenty of large leaved plants growing in the beds to keep the soil from being too exposed and drying out. Maybe even mulching with a light colored mulch.

      Hope that helps.

  2. Note of caution in regard to vines. Last summer my Armenian cucumber vines managed to pull the wire out of my large solar panel which powers the aeration pump in the water tank and the exhaust fan. I have since installed a wire to hold vining plants and ensure they don’t get caught up in the panel wiring.

  3. There is an 8th way to cool & very efficiently too. I designed a geothermal cooler/heater which uses 6″ diameter PVC pipe, trenched underground and connected to my home crawl space. It requires a 30-watt duct fan, which sits onto of the lead PVC duct. It pumps 56 degree air from my crawl space with a return air pipe adjacent to the active pipe. I’ve been using it for several years. It heats in the winter and cools in the summer. PM me for pictures.

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