Updated at: 15-05-2022 - By: Sienna Lewis

How do you keep a greenhouse from overheating? Plants might wilt and die if the temperature in your greenhouse is too high. Optimizing shade, ventilation, and airflow are all effective techniques to keep a greenhouse cool.

Many things influence how cold your greenhouse will be, including the location, climate, and the plants you’re cultivating.

Quick overview of greenhouse cooling options

Cool air can be brought into the greenhouse by vents or windows, and fans can circulate the air. Water evaporation keeps the structure cool, and shade keeps the greenhouse from being too hot.

Keeping your greenhouse cool is a matter of choice, and there are many of them. Generally speaking, these choices fall into three categories:

  • Shade
  • Ventilation and flow of air
  • Cooling the Walls

Shade can be provided by either natural or artificial means. In other words, if you build a greenhouse under or near a tree, it will naturally receive shade. However, if you don’t have any trees, you can utilize plant-shading materials instead.

10 Ways to Keep Your Greenhouse Cool in Summer

To keep your greenhouse at a more comfortable temperature, utilize vents to allow cold air to enter through the roof. Fans, in addition to vents, are essential for allowing cool, fresh air into the greenhouse. Finally, cooling walls use evaporating water to cool the greenhouse’s air.


To begin, why is it necessary for a greenhouse to maintain a cold temperature? You could end up damaging your plants if your greenhouse gets too hot. In the event of excessive heat, plants may:

  • Wilt.
  • Drench in the sun.
  • Become agitated.
  • Let go of all of your leaves/products.

For the majority of plants, there is a preferred temperature range in which they thrive and generate their best yields. Your plants won’t be able to grow as large or as healthy if you exceed this temperature.

When is it too hot? Any temperature above 90 degrees Fahrenheit is considered too hot for most plants. Tomato plants, for example, will not bear fruit in temperatures higher than 90 degrees Fahrenheit.

The ideal temperature range for your greenhouse is 80-85 degrees Fahrenheit. However, some plants are able to live in temperatures lower than that. Warm, wet soil is ideal for beet seeds to sprout. Consider the plants you intend to grow before deciding on the ideal temperature for your greenhouse.

Let’s take a look at the numerous options for keeping your greenhouse cool right now. There may be an upfront investment and some effort required for some of these solutions. Aside from deciding where you want to put your greenhouse, the other options you’ll discover are completely free.


Three methods are available for creating shade:

  • Taking advantage of an existing framework.
  • Utilizing trees and other forms of vegetation.
  • Shade cloth, for example, can be used as a substitute.

Using already-existing structures

It’s critical to determine how much shade you’ll need before building your greenhouse. Consider building your greenhouse so that it shares a wall with an existing structure if you need a lot of shade.

A good example of this is to place your greenhouse so that one of its walls is adjacent to the back wall of your home. Then, at certain times of the day, your home can provide shade for your greenhouse. Pay attention to the times of day and the areas of your home that receive shade.

Remember that the sun rises in the east and sets in the west each day. Consider carefully when you’d like to provide shade for your greenhouse plants.

Using trees and vegetation

You can also use existing trees and vegetation to provide shade for your greenhouse. Your greenhouse will be naturally shaded if you build it near or beneath the leaves of trees.

You should think about locating your greenhouse under or near deciduous trees if you intend to use it all year round. The leaves of deciduous trees drop in the autumn and regrow in the spring.

The benefit of deciduous trees is that their leaves provide much-needed relief from the heat in the summer. It will be easier for your greenhouse to get sunlight in the winter months when the trees’ leaves fall off.

Coniferous trees (evergreens and firs) will not drop their leaves in the fall, therefore be mindful of putting your greenhouse near coniferous trees. Coniferous trees provide year-round shade, so design your greenhouse to take use of this.

Shade cloth and artificial shade

This is the final option for creating shade in your greenhouse, and the most commonly used material is shade cloth. Shade cloth is a blanket that you put over your plants to protect them from the sun’s harmful ultraviolet (UV) radiation.

In your greenhouse, shade cloth can be placed a few feet above your plants, or it might cover the entire structure.

Shade fabric comes in a variety of grades and percentages. Shade cloth that is labeled as 30% will block 30% of UV radiation, for example. Instead of being exposed to the Sun’s UV radiation, a 90 percent shade cloth will shield you from their harmful rays.

Maintaining an ideal greenhouse temperature may include taking down and reinstalling a shade cloth at different times of day depending on your environment and location.

Venting and airflow

Vents and windows are two of the most straightforward ways to keep your greenhouse cool. Cool, fresh air can enter your greenhouse through vents and windows, while hot, stale air can leave.

For greenhouses that need to be kept warm, it is common practice to open and close the vents in the morning and evening, respectively. Even if your summers are hot and dry, you may not need to shut the vents if you live in such an environment.

Timers and sensors

Manual vents that must be opened by hand or electrical vents that open automatically on a timer or sensor are two options to consider when it comes to ventilation. For obvious reasons, timer-controlled electric vents are more expensive than manual ones.

In exchange, you won’t have to worry about whether you opened the vents when you get up in the morning. If you travel frequently and are unable to open your vents on a regular basis, you may want to consider timer-controlled electric vents.

Sensor openers, on the other hand, open your greenhouse vents and windows when the temperature reaches a set level.


Using a fan to circulate air throughout the greenhouse is perhaps the most straightforward approach to keep it cool.

Keeping your greenhouse cool may necessitate the usage of more than one fan, depending on its size. Using two fans in your greenhouse, one to draw in cool air and the other to expel hot air, is a common method of using fans.

At the greenhouse’s entrance, place a fan that is positioned to draw in air from the outside. The cooler air will be drawn in more effectively if it is placed close to the ground.

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Place a second fan near a high vent or window to circulate the air (positioned to blow warm air out of the greenhouse). Your greenhouse will benefit from the optimum possible airflow as a result of this.

Evaporating walls (i.e., cooling walls)

Cooling your greenhouse with evaporative cooling walls is another excellent, cutting-edge method. Using the evaporation of water from wet surfaces and the resulting cooling effect on the air, evaporative cooling can reduce the temperature of your greenhouse by 10–20 degrees Fahrenheit.

You need to keep in mind that evaporative cooling is most effective in dry and arid conditions, when the humidity is low.

Keeping a permeable surface (like cardboard) constantly wet is the key to evaporating walls. Fans are then utilized to draw air into the greenhouse through the moist surface.

For this reason, your greenhouse will be filled with cooler and wetter air because of the breathable surface’s wetness. For those who don’t want to create their own, evaporative walls and cooling devices are available for purchase in stores.

What Temperature Should You Keep Your Greenhouse?

It’s already too hot for your plants in greenhouses that reach 90 degrees Fahrenheit or more. Your plants may wilt, dry out, or cease producing leaves and fruits if your greenhouse is too hot. Your plants need to be at their proper temperature in order to thrive and produce fruit or veggies.

Generally, the greenhouse temperature should be between 80 and 85 degrees F. As a rule of thumb, you should keep your plants in a temperature range of between 65 and 75 degrees Fahrenheit.

How Do You Cool a Greenhouse in High Humidity?

It is possible to cool a greenhouse under high humidity using many methods. A few of the more cost-effective options are as follows:


In order to minimize greenhouse temperatures, you must ensure that the plants have adequate air flow in and out of the greenhouse. Roof and side vents can be installed. In addition, the door of your greenhouse should allow air to flow through it, which will help to keep your plants cool.

Roof vents should cover one-fifth of the greenhouse’s floor space, allowing for a full air change every two to three minutes. However, if installing roof vents is out of the question, simply opening the doors and windows on the sides would do.


Proper shade in your greenhouse can help keep it cool. It’s difficult, though, to add screens to your greenhouse because plants require sunshine to thrive. While shading can help keep a greenhouse cool, it’s important to make sure there’s still plenty of light coming in.

The employment of shadow paints is one of the most effective methods of shading. With shade paints, you may protect your plants from the sun at a low cost. As the summer progresses, you can apply additional coats of paint and then remove them when the weather cools down. There are some greenhouses where shade paint will work better than others. Neats or blinds might be used in place of paint on the walls.


The most cost-effective technique to reduce the temperature in your greenhouse is to dampen it. Aside from the fact that you only need water, it’s almost free. Wetting hard surfaces is an easy way to dampen your greenhouse. Increased humidity from evaporating water aids plants in dealing with high temperatures.

What Are the Benefits of Having a Mini Greenhouse?

One of the best investments you can make for your garden is a small greenhouse. It’s cost-effective, practical, and provides the same advantages as a larger greenhouse. If you’re still undecided about getting a greenhouse, here are a few reasons why it’s a worthwhile investment.

Many varieties to choose from

Some people believe greenhouses are as large as houses because they have floor-to-ceiling windows. While some greenhouses are spectacular in design, most are available in a wide range of sizes and styles. It doesn’t always have to be a huge greenhouse to be a good one. Home gardeners who want to cultivate plants in their backyard will find mini greenhouses to be an excellent choice.

Protect your plants from harmful pests

There are a wide variety of creatures and insects that love to feast on your food. A greenhouse is the greatest way to protect your plants from these pests. In addition, you’ll shield your crops against a variety of pests and illnesses.

Keep your plants safe from harsh weather

Crop losses can be devastating in an instant due to extreme weather conditions such as heavy rain and severe winds. The usage of a tiny greenhouse allows gardeners to grow plants in a variety of weather conditions. For example, even in places where growing circumstances are generally favorable, a single major storm might wipe out months of diligent effort.

Perfect for gardeners with limited space

Gardeners with limited room can benefit from little greenhouses. These limitations should not deter you from growing your own food. Even if you don’t have an outdoor space, you can put your little greenhouse anyplace you like. Despite their diminutive size, these greenhouses offer the same advantages as a larger one.

Ideal for beginners

Inexperienced greenhouse growers can benefit from little greenhouses. Mini greenhouses give you a taste of what it’s like to operate a greenhouse before you invest in a larger one. You can make an informed decision on whether or not to invest in greenhouse gardening once you have identified your personal preferences.

Extend the growing season

You may extend your growing season by planting before the cold season begins with the help of a tiny greenhouse. Plants can be moved into the garden when the risk of frost has passed. Your harvest will come earlier than normal this manner.

How do you stop a greenhouse from overheating?

Provide plants with good air circulation as a means of combating heat. Overheated plants can be cooled down with the use of roof vents, side vents (often louvered), and the greenhouse door.

How hot is too hot for plants in a greenhouse?

Generally speaking, temperatures over 90 degrees Fahrenheit (or 32 degrees Celsius) are considered uncomfortable. If the temperature in your greenhouse increases to or exceeds 90 degrees, you should take steps to reduce it.

What if my greenhouse gets too hot?

Over 85°-90°F (29°-32°C) is not uncommon in greenhouses during the summer. Plants are at risk of death if they are exposed to these conditions. Lower leaves wilt and the edges of the leaves turn brown when the greenhouse temperature is too high.

What temperature should a greenhouse be at night?

In the daytime, it should be 32 degrees Celsius (90 degrees Fahrenheit), while at night, it should be 24 degrees Celsius (75 degrees Fahrenheit).

How can I cool my greenhouse without electricity?

Maintaining proper airflow, dampening down your greenhouse surfaces, and blocking solar radiation strategically with shade cloth or other sources are the most effective strategies to cool a greenhouse without electricity.

Can tomato plants get too hot in greenhouse?

As important as greenhouses are for producing plants such as tomatoes and cucumbers that flourish in warmer climates, greenhouse temperatures can soar to dangerous levels during the summer months.

What temperature should I keep my greenhouse?

Air Conditioning and Heating It is critical to keep the greenhouse temperature between 80 and 85 degrees Fahrenheit, thus this is the first and most crucial instruction.

How to keep a Greenhouse cool in the desert or Hot Summer?

How do you cool a small greenhouse?

To keep your greenhouse cool during summer, here are 10 tips.

  1. A thermometer should be installed.
  2. Ventilation is essential for a well-functioning greenhouse.
  3. Using fans in the greenhouse to circulate the air.
  4. Evaporative cooling systems are a great way to keep your greenhouse cool.
  5. Make use of a fogger or a misting device.
  6. lowering the temperature.
  7. Your plants will thrive if you give them the proper amount of water.
  8. A portable air conditioner can be installed.

Should a greenhouse be in full sun?

Your greenhouse should be located in a location that receives a lot of sunlight, natural lighting, and is shielded from harsh winds and frost pockets. Because of poor drainage and a lack of sunlight, some gardens have damp or water-prone sections.

Should I leave my greenhouse door open?

On bright days, leave all doors and vents open. If it’s still warm outside, you can leave these doors open all night. Vents and doors may have to be partially opened to prevent rapid temperature rises in the event of a sudden change in weather. At a significant price, larger greenhouses can be outfitted with automated ventilation and shade systems.

When can I start using an unheated greenhouse?

During the winter months, an unheated greenhouse can be used to grow greens, start warm-season annuals, propagate landscaping perennials, and protect frost-sensitive plants. You may also produce cold-tolerant vegetables like cabbage and broccoli in an unheated greenhouse in addition to greens like spinach and lettuce.

How do greenhouses stay warm at night?

Add thermal mass. When it comes to keeping greenhouses warm in the winter, a simple solution is to add thermal mass or heat sink. They’re things that take in heat during the day and release it at night. Overnight, they will expel the stored energy.

How much warmer is an unheated greenhouse at night?

This means that even without heating, a greenhouse can get up to 5 degrees Celsius (about 8 degrees Fahrenheit) warmer than the surrounding air. However, an unheated greenhouse can be used in the fall and winter to keep plants from getting frostbite.

Other things to consider

Using materials that collect heat during the day and release heat at night is a fantastic approach to heat a greenhouse. Water, cement, and rocks are examples of heat-absorbing materials.

Choosing the color of pots for your greenhouse is also an important consideration.

The greenhouse will warm up significantly faster if your plants are in plastic pots that are completely black because of the sunlight warming up those dark surfaces. Use white, transparent, or cloth pots to avoid this. However, it is unlikely that this will prevent the greenhouse from overheating.

One final consideration is the need of using thermometers to monitor greenhouse temperatures.

Several thermometers are available that track the hottest and lowest temperatures recorded during the past 24 hours.. If you want to know how hot or cold your greenhouse gets at night or during the day, you can utilize this.

Just a little primer on how to keep a greenhouse cool this season. The location of your greenhouse, the climate and USDA zone in which you live, and the type of plants you’re growing all play a role in how well your greenhouse performs.

Related questions:

How do I keep a greenhouse cool in the desert?

Evaporative cooling walls are a frequent method of keeping a greenhouse cool in the desert. Even though shade and vents assist, they may not be enough to keep you cool. Because of the low humidity found in deserts, evaporative cooling (also known as swamp cooling) can be a useful alternative.

What temperature is too hot for a greenhouse?

In general, a greenhouse cannot tolerate temperatures higher than 90 degrees Fahrenheit. When it comes to the maximum temperature, it all depends on what kind of plants you’re producing. Temperature tolerance of cacti and most succulents is greater than that of other plants such as lettuce and spinach.

What temperature should a greenhouse be kept at?

An ideal temperature range for a greenhouse is between 80 and 85 degrees Fahrenheit in the vast majority of cases. If you’re growing cactus, you’ll want to keep the temperature in your greenhouse as high as possible.

Final Thoughts on How to Keep Your Greenhouse Cool

Keep your greenhouse well aired, put some shade on it, and dampen the walls to keep the temperature down. Fans and a cooling system can also be fitted to increase the feeling of coolness.