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The ideal greenhouse temperature and humidity settings for every season

How to get the right temperature and humidity level for healthy plants

Everyone wishes they could grow their favorite plants and vegetables year-round, but the temperature requirements of each plant make that impossible outside. However, this is where a greenhouse comes in.

If you are new to growing plants in a greenhouse, then you probably don’t understand why temperature and humidity are important. Yes, choosing your greenhouse’s irrigation system and considering your greenhouse’s lights are crucial components for growing plants. But temperature and humidity are factors that weigh heavily on your plants’ health. Whether you are growing vegetables year-round or simply plants that look beautiful, there are steps you can take to support your plants’ growth.

Exterior of greenhouse on concrete patio

The perfect temperature and humidity

While each plant is different, the ideal greenhouse temperature for most plants and vegetables is 80°F. or 27°C. Most plants will grow healthy in this temperature. For humidity, the higher the temperature, the higher the humidity you want. The chart below provides the ideal greenhouse temperature and humidity comparisons:

°F Humidity
50° 83%
61° 89%
68° 91%
86° 95%

However, 80°F. is simply a general guideline. You should look up the ideal temperature for each of your plants if you are worried about disease or infection. For example, if you are growing crops that love a ton of sun, such as tomatoes or melons, then your temperature should be warmer. In general, do not rise above 90°F. (32°C) and do not fall below 75°F. (24°C). Sticking in this range will keep most plants alive and healthy.

The proper temperature must be maintained because these plants are growing in an artificial setting. In such a setting, the temperature and humidity can increase quickly, especially if you have a lot of plants. Thankfully, there are many ways to control the temperature so your plants thrive.

Person going out of greenhouse

Controlling the temperature and humidity

The temperature in a greenhouse is driven by the amount of sunshine and ventilation. The point of greenhouses is to trap the sun’s heat; while that makes it easy to get a hot room, it does not make it easy to control that heat. However, there are a few simple ways to moderate the temperature and humidity.

The biggest thing to create is ventilation. While that could mean installing vents in the roof, it could also simply mean opening windows and doors to create a cross breeze. You could also use air conditioning to bring the temperature down. During the winter season, pull in the cold air and exhaust the warm air with fans to reduce the humidity.

Depending on what you are growing, you can even trick the plants into thinking they are in a different season. Extra lights can imitate the sun during the winter while heaters can increase the temperature. However, this can be set up to be almost fully automatic using greenhouse timers. This brings us to the tools you can use for proper greenhouse temperature and humidity monitoring.


Tools for greenhouse monitoring

There are great tools for a greenhouse that can easily maintain it. While these devices are not necessary, greenhouses are artificial settings that need proper maintenance and care at all times, especially during the off-season. These tools make that much easier.

Greenhouse temperature alarm

This alarm tracks potential problems in the greenhouse, such as power outages, temperature fluctuations, water damage, and bug intrusion. Some models go one step further and will send you a text message of any such occurrence.

Greenhouse temperature control system

This tool provides proper and dependable heating and cooling options for your greenhouse. Keeping the temperature at an optimum level all year-round is important. Despite the outside weather, you can maintain the temperature to whatever is needed.

Greenhouse temperature sensors

One of the coolest things (no pun intended) about greenhouses is the chance to automate them. Sensors monitor the temperature in the greenhouse and can automatically activate vented roofs, side vents, and fans to keep the temperature at the optimum level. Some sensor models can also alert you if these systems stop running or run into a problem.

Remote temperature monitor

Keeping track of the greenhouse temperature throughout the day is very important. How can you know how to grow your plants without an accurate reading of how hot it is throughout the day? A temperature monitor lets you see broad data about the temperature over a defined period of time. The temperature is recorded so you can view it at any moment.

Keeping optimum temperatures and humidity is very important for keeping your plants healthy. While it depends on which vegetables and plants you are growing, there are tools and tips anyone can implement to increase their chances at growing crops year-round, automatic and (almost) hassle-free.

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Niko Vercelletto
Former Digital Trends Contributor
Niko Vercelletto lives in Lansing, Michigan. He is passionate about going into depressive spirals thanks to the Detroit Lions…
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