Skip to main content

How to keep your greenhouse cool in the summer

When most people think about temperatures in their greenhouses, it’s all about wintertime and keeping it warm and cozy. However, they really ought to be considering how to keep their greenhouses cool in the summer. When temperatures shoot up during the summer months, your plants can suffer. That’s why it’s crucial to bring temperatures down so your plants will produce and you can realize a plentiful harvest during this season.

There are several ways to ensure your greenhouse stays cool. A lot of these methods are DIY and depend heavily on your available budget and precisely how much cooling you need. Below are six great ways to keep your greenhouse cool in the summer.

Related Videos
A man working in a greenhouse

What temperature is too high for your greenhouse?

Before talking about how to lower temperatures, you should know how high is too high. Essentially, plants don’t do well in temperatures above 90°F (32°C). For that reason, you need to ensure that you keep the heat down and temperatures below the levels just mentioned.

However, if you live in a hotter location where outdoor temperatures regularly rise above 100°F (38°C), you might find it difficult to keep temperatures down inside your greenhouse. If that’s the case, you’ll want to take one or more of the steps outlined below to ensure cooler temperatures.


What in the world is transpiration, you ask? Well, it’s the process of water moving through a plant and then evaporating through its stems, leaves, and flowers. Plants need water, just like all living things. However, the plant only uses a small amount of the water taken up by its roots for metabolism and growth. The rest, which amounts to somewhere between 97 and 99 percent, is lost by transpiration.

What does this have to do with cooling your greenhouse? Well, in essence, the plants that live in your greenhouse act as little evaporative coolers through the process of transpiration. As a result, enough plants in your greenhouse will lower the interior temperature even if you take no other action.

Create shade

It may sound like a no-brainer, but creating shade is a great way to help lower the temperature inside your greenhouse. Obviously, you can help ensure that temperatures are cooler inside than outside by blocking out the sun and its heat-producing rays. You can create shade in several ways. One way is to strategically placing plants with large leaves in areas where they can block out the sun. For instance, planting trees with naturally large leaves on the southwest side of your greenhouse will do the trick nicely.

Another way to ensure shade is to purchase shade cloths, which can reduce sunlight by up to 50 percent while still providing enough nourishing rays that your plants can continue photosynthesis.

Use a misting system

A misting system is an excellent way to cool down your greenhouse. However, you have to be careful and monitor moisture levels. Too much moisture can create perfect conditions for the growth of fungus and mold. If you’re careful, however, a misting system can complement your shading efforts.

Install a portable air conditioner

Another excellent option is to purchase a portable air conditioner, especially if you have a larger greenhouse. They’re cost-effective and energy-efficient. Plus, a dehumidifier is typically a part of the system. The downside is the price tag. Portable air conditioners can be pretty expensive. For that reason, this option isn’t a good one if you have a smaller budget.

Fans and ventilation

Using large fans in combination with proper ventilation can cool the interior of your greenhouse substantially. Remember that proper ventilation allows fresh air to reach your plants in addition and helps to control humidity and the overall temperature. Providing ventilation is important since greenhouse structures aren’t normally built with ventilation in mind.

Exterior of greenhouse in a planted field

Wrapping up

The truth is that you’re risking all your hard work if you don’t keep your greenhouse at optimal temperatures. Hotter temperatures provide pests and disease organisms with better opportunities to attack your plants. Plus, higher temperatures cause your plants to dry out and wilt. If temperatures get too high, they could even stop growing completely.

Should any of the above happen, you won’t have a good harvest. Most vegetables grow well in cooler conditions (which is not to say cold conditions), and rising temperatures mean less growth. If you want to protect your plants throughout the summer, then keep your greenhouse cool.

Editors' Recommendations

A complete guide to the best lights to choose for your greenhouse
Houseplants under grow lights

Just like growing houseplants indoors, growing plants in a greenhouse requires specific care and a suitable environment. Even though the greenhouse will have some light from the sun coming in, the glass panes are often filtered in some kind of way to prevent your plant’s leaves from scorching. Enter grow lights. They’re used most commonly in darker spaces or during colder months; however, they're greatly beneficial to your greenhouse plants and help ensure that the plants are getting the light they need to thrive.

Can you have an indoor greenhouse?
Absolutely! Indoor greenhouses are revered for how sustainable and inexpensive they can be. An indoor greenhouse with lights can be installed anywhere in the home where you have the space, and it’s a perfect place to grow things like fruits, herbs, and veggies indoors. If you’re only planning to grow a couple herbs, you can get something as small as a tabletop greenhouse! It will fit a few plants, won’t take up too much space, and will add to the aesthetic of a room while letting you grow plants in a unique way.

Read more
Good, better, best: Portable greenhouses for your winter garden
greenhouse in winter

There are many exciting plants to grow in your garden, but not all of them are suited to your particular climate. A greenhouse can significantly extend the range of plants you can grow, as well as what seasons you can start those plants in. A full size greenhouse is expensive and hard to move, but portable greenhouses are much more accessible. There are a lot of factors to consider though, including durability, what materials it’s made of, size, how easy it is to put up and take down, and, of course, cost. If this seems overwhelming, then why not let us do some of the work for you? We’ve got three portable greenhouses for your consideration, with all the factors laid out for you!

Good: Costway Portable Mini Greenhouse
The Costway Portable Mini Greenhouse covers all the essentials of a greenhouse. It's made of clear plastic fitted over a hard plastic frame. The plastic covering is waterproof, and lets in light. It comes with four shelves, two for each side, and has enough floor space for a couple additional potted plants. This greenhouse is easy to assemble and is lightweight enough to be moved easily whenever you need to, weighing only 16 pounds when assembled.

Read more
Start these vegetables in the greenhouse this winter for a delicious harvest
vegetables to start in the greenhouse winter harvesting carrots

Many people associate garden-fresh vegetables and fruits with the fall or warmer-weather months. But if you have a greenhouse or access to a greenhouse, you don’t have to halt production just because winter has arrived.

Are greenhouses suitable for growing vegetables when thermometers drop? You bet. A vegetable greenhouse can give back a significant yield in the winter, especially if you know which vegetables do well in this environment. It may take a little extra knowledge and focus, but most experienced gardeners should be able to transition to the winter vegetable greenhouse without any major headaches.

Read more