Updated at: 17-03-2023 - By: Sienna Lewis

As a general rule, a greenhouse’s temperature shouldn’t exceed 80 degrees Fahrenheit.

If the temperature in your greenhouse rises above 90 degrees Fahrenheit, it is too hot. Temperatures this high will kill even the most heat-resistant plants and vegetables. The optimal temperature for plants to thrive is between 80 and 85 degrees Fahrenheit.

Here are some strategies to cool down your greenhouse if it is too hot:

Open the doors and windows

Allow fresh air into your greenhouse. Roll up the plastic sheet and allow the air to circulate by opening the doors and windows or unrolling the sheet.

Use fans

For greenhouse cooling, fans are preferable over opening the doors and windows. Fresh air is drawn in by the movement of the fans. Fans should not be placed on the ceiling or ground level for this strategy to work. To move air over and through your plants, set the fans at a height of six feet or more in front of vents.

Is My Greenhouse Too Hot?

Use shade

Shade is another method for lowering greenhouse temperatures. This shields your greenhouse from the sweltering rays of the sun. Shade cloth, vines, or a liquid shading compound can all be used.

What Grows Well in a Hot Greenhouse?

Because summer temperatures soar, it’s preferable to grow plants that do well in hot climates. You just need to make sure they get sufficient of water so that they can keep producing throughout the season. The following plants are worthy of consideration:


Warm weather is ideal for growing greens. Planting them in a greenhouse, on the other hand, will expedite their growth and harvest.


Temperatures in the 90s are ideal for growing luscious melons. Don’t overwater your plants, especially as the melons get closer to ripeness. Melons get tasteless when water is added in excess. It’s ideal to grow heirloom melons in hot and dry climates because of their deep roots in the soil.


The faster the maize grows, the more it can handle the heat. It’s important, though, to keep the soil well-watered during the growing season. A lot of water is absorbed by the kernels of corn to make them crispy and delicious.

Sweet Potatoes

Sweet potatoes are popular in the southern United States, but they’re catching on in the north. As with any other plant, sweet potatoes need even moisture in order to grow in the heat. Before the soil temperature drops below 55 degrees F, pick your sweet potatoes.


Heat-resistant spicy peppers are more effective than sweet ones in the long run. Big Bertha, Cal Wonder, Cubanelle, and Sweet Banana are all sweet peppers that can be grown in your garden.

Top Reasons Why You Should Invest in a Greenhouse

You can regulate the climate in a greenhouse. On warmer days, you can open the windows, shield your plants from heavy rains and strong winds, and provide shade from the hot sun. You may also control the humidity levels to guarantee that your plants are growing well at the same time.

It’s a good idea to get a greenhouse for a few reasons:

Prevent pests

All of your hard work might be undone by pests and other critters. Insects, such as aphids and mites, can’t get to your plants if you keep them in an enclosed location. There is no need for hazardous pesticides or chemicals to keep these pests out of your home or business.

A longer growing season

Because they maintain a more consistent temperature, greenhouses allow for a longer growing season. This extends the planting season by many months.

Protect plants from extreme weather

Your plants will be protected from adverse weather conditions like heavy rain, strong winds and hail, storms and blistering heat by placing them in a greenhouse Greenhouses, as we’ve seen, may protect plants from temperature fluctuations.

The delicate plants can be damaged by strong winds and the sun’s rays if they are exposed. To ensure that your plants get the maximum amount of light and ventilation, go for glass greenhouses or those with a translucent plastic roof. Make careful to protect your plants and produce from the elements by using a greenhouse.

More plants to choose from

Consider a greenhouse if you plan to cultivate plants that aren’t native to your location. As previously stated, greenhouses allow you to manage the temperature independent of the weather conditions outside.

Even though it is winter, you can grow warm-season vegetables because of the warmth and insulation provided. You may customize the climate in a greenhouse to suit the needs of the plants you wish to cultivate there. You only need to know what your plants need in order to develop and thrive.

How does the type of plant affect what temperature is too hot?

It’s crucial to know your plants’ needs because the appropriate greenhouse temperature differs from plant to plant.

It’s critical to understand the optimal temperature ranges for various plant types.

You’ll find this information on the seed packet, so keep an eye out for it the next time you go shopping for something for your greenhouse.

Knowing if your plants can handle the heat is extremely crucial.

Heat-tolerant plants

Temperatures as high as 90 degrees Fahrenheit can sustain some plants. Temperatures between 80 and 90 degrees Fahrenheit are ideal for plants that thrive in the heat.

Summer crops are typically referred to as such since they are able to tolerate the heat and remain productive. Among them are the following:



Potatoes with a sweet taste






The chiles

Even yet, a greenhouse with a temperature of 90 degrees Fahrenheit is too hot for any of the plants listed above.

Photosynthesis slows down as the temperature rises above a certain level.

As long as you keep an eye on the temperature in your greenhouse, you should be fine.

While these plants may be tough, they aren’t the only ones that are hardy.

As a result, there’s no reason to be alarmed.

A smart choice for beginners, those concerned about their greenhouse getting too hot, or those who have had problems with their plants in the past would be to plant any of these varieties.

Heat-sensitive plants

Heat-sensitive plants, on the other hand, require special attention.

Temperatures between 75 and 85 degrees Fahrenheit are ideal for these plants. These are only a few examples:



The Brussels sprouts







It’s time to get some pork (Bok choy)


Plants like this aren’t the “resident tough guys” I previously mentioned.

If you want to get a good harvest from heat-sensitive plants, you’ll need to lower the greenhouse temperature. 85 degrees Fahrenheit is too hot for heat-sensitive pants.

Summer is the time of year when most gardeners have difficulty keeping their greenhouses from overheating.

Remember that 85 degrees Fahrenheit is too hot for beets to grow in your garden.

How does your location affect what temperature is too hot?

Make sure to keep in mind the weather in your area before making a decision.

When it comes to greenhouses, those who live in highly hot areas need to be extra careful.

Alaskan greenhouse owners, on the other hand, will face a different challenge: how to keep their greenhouses warm enough!

There’s more to take into account than just how hot or cold it is where you live.

People who live in humid climates should pay extra attention to their greenhouse’s temperature.

Plants can suffer from fungal infections and mildew as a result of the combination of high temperatures and excessive humidity.

So, greenhouse growers, take command! The lower end of the recommended temperature ranges for your specific plants should be your goal if you live in a hot and humid area.

The American South and Southwest, Mexico, India, the Philippines, and other countries in the subtropics have the most difficulty controlling the temperature of their greenhouses.

Don’t worry about it if you live in a place like this!

Later in this post, we’ll discuss ways to keep your greenhouse cool.

How to check the temperature of your greenhouse

Don’t buy a mercury thermometer, for the sake of your health. There are simply too many drawbacks to consider them all at this time.

Mercury thermometers are notoriously unreliable and, if mishandled, quite hazardous.

So, they’re actually insufficient for monitoring greenhouse temperatures.

Take advantage of the thermocouple to get an accurate reading of your temperature.

What is a thermos?

Thermocouples, which you may not be familiar with, are very fascinating devices (no pun intended).

Two pieces of metal are twisted together to form a thermocouple.

They generate a voltage in proportion to the difference in their temperatures.

Is this what happened?

It’s simple to correctly measure temperature, which provides you with an accurate greenhouse temperature reading.

Which, if you still have a hankering to produce beets, you’ll require.

In order to acquire the most accurate reading, where should you set your thermocouple.

Protect your sensor from the sun and other sources of light.

The thermocouple will give an incorrect reading if it is not.

If the thermocouple is to function well, it should be placed in an area with a steady flow of air.

Make sure your thermocouple is housed in an aspirated box of reflective color to meet these standards.

Another common blunder is to place the thermocouple at an excessively high elevation.

Remember that the heat rises. In this case, the thermocouple will read a few degrees higher than what your plants are actually experiencing.

As a result, your thermocouple should be placed at or near the plant’s height.

Whether you don’t check your thermocouple often, you won’t be able to tell if your greenhouse is getting too hot.

In addition, make certain that your thermocouple is still in good working order and that it is situated correctly.

The Summer Sun is Overheating Your Greenhouse, Here's How to Cool it Down | GrowSpan

How to lower the temperature in your greenhouse

What do you do now that you’ve gathered so much knowledge about the ideal temperature for a greenhouse?

When it comes to greenhouses, there’s no need to succumb to the whims of Mother Nature.

In order to extend the growing season and increase crop yields, there are numerous techniques to lower the temperature of your greenhouse.

The following approaches and technologies can help you lower the temperature of your greenhouse:

  • Defintion of ventilation
  • Fans
  • Shade
  • Watering
  • Bringing the tempo down
  • Fan misters and evaporative cooling
  • a fan installed beneath the ground

Ventilation systems

Most greenhouses come pre-equipped with ventilation systems, making it simple to maintain a comfortable temperature in your growing space.

Ventilation systems work by moving air through plants that have become too hot.

Your greenhouse’s temperature will be lower if you open the door and the vents on the roof and side walls to allow appropriate airflow.

Lowering the temperature in your greenhouse has never been easier or cheaper than with this one-button fix.


Fans work in the same way as ventilation systems: they circulate air around your plants to keep them cool.

If your greenhouse’s ventilation system isn’t getting the job done, you may want to consider purchasing a fan.

Direct-drive fan units powered by solar panels are also popular and don’t require any electricity at all.


Cooler temperatures are a direct result of the shadow.

Creating shade in your greenhouse can be done in a variety of ways.

Creating natural shade in your greenhouse by growing plants with huge leaves and tall canopies is a terrific idea.

Shade cloths are also an option.

Materials for shade cloths and netting range widely, but the best ones are made of aluminum, which doesn’t heat up your greenhouse when it becomes hot like many other materials do.

You should also read the whole article on shade cloth percentages.


You can’t lower the temperature of your greenhouse by watering your plants, yet it’s the most crucial thing you can do for your plants.

Transpiration, or sweat, is how plants regulate their internal temperature.

Plants, like us, lose moisture when they are exposed to heat and sunlight. They will perish if they are unable to sweat, as their body has no way of naturally combating the heat.

Damping down

To reduce the temperature in your greenhouse, utilize this simple method.

To clean your greenhouse, all you have to do is spray the floor with a hose.

A cooling effect is caused by water evaporation, which cools down other parts of your greenhouse as well.

Despite its simplicity, this method is extremely effective. And it also has the additional benefit of making insect conditions less favorable.

Evaporative coolers and fog misters

The use of an electronic cooling system in a greenhouse is another frequent method for reducing summer heat.

These devices are powered by electricity and can be quite pricey.

A pad-and-fan system (also known as an evaporative cooler or swamp cooler) and a fog system are two popular models.

A mist system is another common choice for larger greenhouses.

Only when all other solutions have failed do you need to resort to the most expensive ones.

Undersoil fan

This is a less-often-used alternative, but it’s actually extremely effective. It’s essentially a greenhouse’s geothermal cooling system.

It is possible to purchase a fan system that is installed in the soil beneath your greenhouse and uses pipes in the soil to expel the greenhouse’s hot air.

The temperature of your greenhouse will be drastically reduced if this is combined with adequate air flow through ventilation.

With this method, the greenhouse’s warm air is cooled down by transferring its heat to the earth beneath it, which is much cooler than the greenhouse’s air (often approximately 55 degrees Fahrenheit).

Have you grasped the gist? Now, during the height of summer, keep those plants cool!

Why do Greenhouses Get Too Hot?

“Don’t I want my greenhouse to be hot?” you may ask yourself. Plants need sunlight, and most people build greenhouses to provide it. But too much sunlight can be harmful to plants.

In a greenhouse, a reasonable amount of heat and water are kept in to maintain a sufficient level of humidity and temperature. Slowing the rate at which heat exits the greenhouse accomplishes this goal.

Because of the heat that is trapped inside the greenhouse, it aids in warming the earth below it. As a result, plants within thrive as a result of the warm ground.

It’s possible that the greenhouse temperature can rise even further when the weather is extremely hot outside. Even the best greenhouse garden might be ruined by these high temps.

Overheated greenhouses are preferable to those that are kept at a little lower temperature. For this reason, it’s essential to keep your plants cool.

Take a look at what vegetables do best when the temperature is just right.

It’s also possible for plant growth temperatures to change. Some of those temperatures are shown here.

Temperatures can reach these levels for months at a time in most parts of the country during the summer months. The temperatures will rise even higher in your greenhouse, indicating that you have an overheated greenhouse.

Get a thermometer to keep an eye on your greenhouse’s temperature. For the best of all worlds, here’s an Amazon thermometer to consider. Humidity is equally as crucial as temperature in determining the overall health of a building.

It is now time to figure out how you can lower the temperature of your greenhouse and maintain your plants healthy and vigorous.

Ways to Cool Down Your Greenhouse

The good news is that keeping your greenhouse cool isn’t as difficult as you would think. Here are some suggestions on how to reduce the temperature in your home.

  • The greenhouse’s door should be opened.
  • Add fans to your social media accounts.
  • Remove a few of the walls.
  • Shade yourself with a tarpaulin.
  • Use evaporative cooling systems
  • Strategically place large-leaved plants in your garden.
  • Utilize storage containers for water.
  • Make use of misters or foggers.
  • If you’re using grow lights, turn them down.
  • Take advantage of an air conditioner.

Open the Greenhouse Door

More air can flow through your greenhouse by opening the door. This should bring the temperature down by a few degrees. Hopefully. Some fans can also help circulate the air.

Remove Some Panels

By allowing heat to escape and bringing in fresh air from the outside, removing panels from the sides and roof of your greenhouse can help improve air circulation.

Use a Shade Cover

To keep your greenhouse cool during the hottest part of the day, cover the roof and the sunniest side of the structure.

When it comes to greenhouse lighting, you’ll need somewhere between 45 and 70 percent coverage. A variety of materials are available, including this aluminum shade cloth I found on Amazon.

Shade cloth should be used sparingly. Providing too much shade can stunt plant growth and cause the plants to extend out in an effort to reach the sun.

Use Evaporative Coolers

Cooling your greenhouse using evaporative coolers saves electricity. Water is collected and stored within on a pad, which is how they work. Cooled air is blown back into the greenhouse as needed by passing over the pad.

When in use, evaporative coolers can reduce the temperature of your greenhouse by up to 20 degrees. You can buy an evaporative cooler on Amazon.

Plant Large-leaved Plants Strategically

When planning the arrangement of your greenhouse, think about how much shade you need. Soil cooling is made possible by plants with huge leaves that are carefully positioned. Temperatures are lower when the soil is cooler.

These plants, together with fig trees, grapevines, crepe myrtle and wisteria on an arbor, are all excellent sources of shade.

Use Water Tanks

Placement of a huge water tank or even smaller water containers around the greenhouse can also assist lower the temperature of the greenhouse. The heat is taken up by the water. Amazon has a 50-gallon water tank.

Use Misters or Foggers

The evaporation of water droplets from a mister or fogger lowers the temperature in your greenhouse.

On Amazon, I found a moderately priced mister.

Also on Amazon, here’s a fogger you might want to take a look at.

When using a mister or fogger, be sure to monitor the humidity level. Mould and unwelcome pests that thrive in warm, damp settings might develop on your plants when the humidity in your greenhouse is too high.

Dim Your Grow Lights:

In the summer, you shouldn’t have to use grow lights as much, but if you must, turn them down or turn them off throughout the day. When it’s cooler at night, you can switch them back on.

On Amazon, you can find a timer-equipped set of grow lights. You may also dim the lights on this set.

There are a variety of cooling systems to choose from depending on your greenhouse’s temperature and your budget. In order to acquire the greatest outcomes, you might combine various options.

Proper Ventilation Helps With Temperature

A healthy greenhouse relies heavily on the proper amount of airflow. Ventilation, in addition to supplying plants with carbon dioxide, also reduces humidity and temperature. To avoid overheating and moisture buildup, it’s important to ventilate your greenhouse. There is no way you or your plants can prevail in that situation, no matter how much you know about gardening.

When it comes to ventilating your greenhouse, there are two options: natural ventilation and mechanical. An introduction to the fundamentals of each system is provided here.

  • Natural ventilation: This technique is based on the idea of thermal buoyancy and relies on natural phenomena. Atmospheric evaporation occurs when warm and moist conditions are replaced by colder conditions. Vents in your greenhouse are used to do this. Natural ventilation has the drawback of putting you at the mercy of the weather, which means you have less control.
  • The mechanical ventilation system is exactly what it sounds like: mechanical in nature.. The greenhouse’s opposite end has shutters that let in cooler air while an exhaust fan removes hot air. This system is much more under your control.

Knowing the fundamentals has prepared us for a closer look at each system’s components, both in terms of their equipment and where they are located.

Natural Ventilation

Roof and sidewall vents can be installed to bring fresh air into your home. Each of your greenhouse’s vents should have a combined surface area of 20% of the greenhouse’s total floor area. Some examples of how those figures work out can be seen herein.

Vents in the roof allow hot air to escape from the greenhouse as it rises. A vacuum is created by the air exiting the vehicle, and this new, cooler air is drawn in through the sidewall vents.

Using natural ventilation in your greenhouse is especially beneficial on chilly days when the temperature differential between the inside and outside of your greenhouse is more significant. When the temperature difference between the air and the water is small, there is no buoyancy effect.

A solar-powered vent opener is a useful piece of equipment for improving the flow of fresh air. To operate, all that is needed is for the paraffin wax inside to expand due to a rise in temperature. On a hot day, this saves you from making several journeys outside.

On Amazon, you’ll find a good solar vent opener.

A natural ventilation system can also use large electric fans to help move air. It would be a great assistance if Amazon had a giant fan like this one.

Mechanical Ventilation

A mechanical ventilation system must be matched to the size of your greenhouse in order to be effective. Cubic feet per minute (CFM) is the unit of measurement for a fan’s performance.

For the most part, a minute-to-minute air change is ideal. In order to get the rating you need, all you have to do is figure out the volume of your greenhouse. The term “volume” refers to the sum of a surface’s length, width, and height. There are some examples in this table.

The exhaust fan should be placed at the top of the greenhouse, while the intake shutters should be lower and spread out across the greenhouse, because heat rises. Air is forced through the greenhouse in this manner.

So, if your greenhouse gets too hot, what form of ventilation is ideal for you? There are a few variables that come into play.

  • Both systems are comparable in terms of their initial investment in terms of cost. Naturally ventilated spaces are less expensive in the long run.
  • Natural ventilation systems require a greater time commitment because they cannot be set to operate on a predetermined schedule.
  • For a small or large greenhouse, a mechanical system would require too much power and money, but for a medium-sized greenhouse, it would be ideal.

Related Questions

How do you cool down a greenhouse?

There are three basic ways to cool down a greenhouse: evaporation, ventilation, and shading.

There are a variety of alternatives for each strategy. Open a window or vent to get ventilation, or use a fan if you’d like to go all out.

Shade netting, shade fabric, or shade paint can all be used for shading. A damper, evaporative chiller, or fog misters can all be used to evaporation.

How Hot Can a Greenhouse Get - Krostrade

How can I reduce the heat in my greenhouse?

A greenhouse’s six most popular methods for reducing heat are: air conditioning (evaporative cooling), fans, shade fabric, shade paint, and damping.

Additionally, the evaporative cooling action of fog misters might be utilized as a seventh alternative.

How to regulate temperature in a greenhouse?

Heating and cooling greenhouses are necessary in order to maintain a stable temperature throughout the year (in summer).

Heating and cooling are accomplished through the use of evaporation and ventilation. Various methods of heating include those that utilize insulation, weather stripping, thermal mass, and heaters. Controlling the temperature in a greenhouse can be made simpler and more convenient using automation.

What level of humidity is too much for a greenhouse?

Your greenhouse’s humidity must be controlled in the same way as the temperature.

Unfortunately, there isn’t a single perfect humidity level. When there is no moist foliage in your greenhouse, you’ll have the best humidity. Wet foliage can lead to a variety of issues, including as fungus and mildew.

Thoughts on the Answer to “What Temperature is Too Hot for a Greenhouse?”

Now that you know how hot a greenhouse can get, be sure that yours doesn’t go any hotter than 90 degrees Fahrenheit. Your plants may shrivel and die if you don’t take care of them. The ideal growing conditions for your plants should be understood so that the greenhouse may be tailored to meet those needs.