3 Best Humidifiers for Greenhouses

3 Best Humidifiers for Greenhouses: To maintain healthy plants, humidification must be maintained constantly and at a healthy level. If the humidity levels drop in your greenhouse, photosynthesis slows down, and your plants are more prone to disease.

Best Humidifiers for Greenhouses
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It will be necessary to buy a humidifier unless your plants can withstand dry conditions. Instead of a humidifier, consider a dehumidifier if your plants are designed to thrive in dry conditions. Discover how to select the best humidifier for your greenhouse by checking out our top picks.

Reviews of the Best Humidifiers for Greenhouses

Humidity refers to the amount of water vapor in the air, and some plants simply need more humidity because their root systems aren’t designed to hold enough water. Humidifiers measure the level of humidity and restore it to optimum levels, helping the plants thrive, so they’re more potent at fighting off infections and diseases. Check out our top picks.

Evergreen Pet Supplies Reptile Humidifier

Designed to produce up to 300 ml of mist per hour, this is a compact ultrasonic humidifier. Filling is easy with the no-spill valve on the 2-liter tank.

This humidifier is ideal for first-time humidifier buyers because it’s budget-friendly and easy to assemble. The hose on this humidifier allows you to adjust it to spray mist in specific areas, unlike other humidifiers.

This humidifier is an excellent choice for a small greenhouse because of its compact design. Depending on your plants’ needs, you can control the output from a light mist to a dense fog. In addition, it shuts off automatically when it runs out of water to ensure safety. Despite that, this humidifier can only be used with distilled water, and at higher output levels it becomes quite loud.

What We Like

  • Compact and affordable humidifier.
  • Controllable mist output depending on your plants’ needs.
  • Adjustable hose to spray mist.
  • Automatically shuts off when the water runs out.

What We Don’t Like

  • You can only use distilled water with this humidifier.
  • Is a little loud.

Ideal Air HGC700861 Industrial-Grade Humidifier

As it’s designed to cover an area up to 1610 square feet, this humidifier is ideal for bigger greenhouses since it helps plants grow by maintaining healthy levels of humidity. In dry weather, this will be excellent because it can produce 200 pints of water a day.

You only need to connect the humidifier to the water supply, so you won’t have to worry about refilling it. To maintain a healthy climate in the greenhouse, the mist is spread in multiple directions by the multi-directional head.

Moreover, its powerful motor will last for years of continuous use. The only disadvantage is that the humidifier is noisier and more expensive.

What We Like

  • Suitable for a bigger greenhouse.
  • High level of output per day.
  • Multi-directional head.
  • Connects directly to the water supply.

What We Don’t Like

  • More expensive than other models.
  • Loud operation.

TaoTronics 4L Cool Mist Ultrasonic Humidifier

This humidifier is perfect for medium greenhouses, because it can cover a space of 300 square feet. Based on the selected output level, it can last up to 30 hours with a 4-liter capacity.

Using the LED display, you can check the current humidity levels and make necessary adjustments to provide your plants with optimal moisture. A mist level can be set into three different settings based on the temperature. By activating the night mode, you can also set the timer to turn off the humidifier.

Due to the built-in filter, this humidifier only releases clean water. It shuts off when the water runs out to protect the motor, and there is a clear window so you can see the level of water.

If the humidity levels do not drop drastically in your greenhouse, you can choose this humidifier. The humidifier’s humidity must be reset every time it is restarted.

What We Like

  • Affordable humidifier for small and medium-sized greenhouses.
  • Long-lasting operation with adjustable mist level.
  • Adjustable timer.
  • Built-in filter.

What We Don’t Like

  • Doesn’t work in extremely dry conditions.
  • The settings need to be reset every time you restart the humidifier.

How to Choose the Best Humidifier for Greenhouse

How to Choose the Best Greenhouse Humidifier
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A greenhouse allows you to grow plants when the weather conditions aren’t optimum. Maintaining adequate humidity and moisture levels allows plants to better adapt to this controlled environment. Here are a few factors to help you choose the right humidifier for your greenhouse.

Type of Humidifier

Warm mist humidifiers are the most common type. This increases the level of humidity by warming up the water, which evaporates and turns to water vapor. By moving air over wicking material, evaporative humidifiers create water vapor.

A humidifier that uses ultrasonic vibrations increases evaporation. It produces a better mist.

Temperature of Mist

The plants won’t suffer any effects from cold or hot mist since the temperature difference won’t be noticeable. A hot mist, however, tends to be of better quality as the heat will purify the water. Electricity is also required for a hot mist humidifier. Cold mist humidifiers use less electricity and require less maintenance.

Covered Area

A small humidifier will work if you have a small or medium-sized greenhouse. If you live in extremely dry conditions or have a big greenhouse, you should invest in a larger industrial-grade humidifier.

Refill Type

Most humidifiers come with a tank that you can easily refill. However, if you have a big greenhouse that you need to run for longer hours, you should consider a humidifier that directly connects to the water supply.

Run Time

A humidifier that runs for a long time will use more electricity. It also needs to be filled more often. The run time depends on how you adjust the mist output.

Wrap Up

A reliable humidifier that adequately provides your plants with humidity is what you need to control and maintain the humidity level in your greenhouse. A medium-sized humidifier, we recommend the Evergreen Pet Supplies Reptile Humidifier.

Ideal Air’s HGC700861 Industrial-Grade Humidifier is good if you have a very large greenhouse since it provides enough moisture to cover large areas.

Controlling Greenhouse Humidity During Summer’s Hottest Months

What Is Humidity?


It’s important to understand what humidity is and why certain plants need higher or lower levels of it. By understanding this, we’re able to customize our plant’s environments so they truly thrive.

At its simplest, humidity is a measure of the amount of water vapor present in the air.

There are two common definitions of humidity:

Relative humidity – How much water vapor the air is currently holding relative to how much it can hold at a certain temperature.

Absolute humidity – How much water is in a cubic meter of air.

The higher the temperature of air in a given space, the more water vapor it’s able to hold. This is why plants that require high humidity usually require higher temperatures as well — the two go hand-in-hand. Here are a few different growing environments for reference:

  • Desert – Hot air, low humidity due to low water availability
  • Arctic – Cool air, high water availability but still low humidity

When I said that warm air “holds” more water, that wasn’t quite accurate. Warmer air simply causes water to evaporate faster, resulting in more water vapor in the air.

Why Do Some Plants Need Higher Humidity?

A plant’s adaptation to its native environment evolved over time. Plants that grow in humid environments have responded by reducing the amount of water they can hold in their leaves. Similarly, plants native to humid areas have adapted to do the opposite of what succulents do; they hold a lot of water in their leaves. In addition, some plants don’t have robust root systems, so they can’t draw much water from the soil.

Additionally, epiphytes are plants that absorb all of the water they need from their surroundings, so they require high humidity to thrive.

Common Humidity Levels For Houseplants

All plants are different and will require different levels of humidity. However, here are some general guidelines for common houseplants:

  • Orchids – 40-70%
  • Ferns – 40-50%
  • Most other houseplants: 40-60%

Types of Plant Humidifiers

Humidifiers work in three basic ways: warm mist, ultrasonic, and evaporative.

Types of Humidifiers
Comparison of three types of humidifiers

Warm Mist Humidifiers: These are the most common type of humidifiers on the market. The way they work is simple: they heat water up to a high temperature, causing it to become water vapor. It’s then sent out into the environment to boost the humidity of the surrounding area.

Ultrasonic Humidifiers: These are a unique type of humidifier that use vibration to increase the evaporation rate of the water in the tank. You’ll be able to tell it’s an ultrasonic humidifier by the quality of the mist — it’s quite fine and wispy.

Evaporative Humidifiers: These use airflow to create vapor. You may know of swamp coolers, which work similarly. Evaporative coolers draw water from their tanks over a wicking material (like cloth or felt).

How an evaporative humidifier works
How an evaporative humidifier works source

Next, a fan forces air over the wet wicking material, which adds water vapor to the air. It then flows out into your garden, giving your plants the humidity they so desperately want.

Warm vs. Cold Mist

The temperature of the mist produced by your humidifier may matter. It doesn’t! There really is no point in worrying about it. Regardless of whether it’s warm or cold, the temperature increase or decrease will be barely noticeable.

A benefit of warm-mist humidifiers is that water vapor is purified by evaporation. However, since they need to heat the water, they use more electricity.

As a result, cold-misting humidifiers use less energy and can be run for longer periods of time, making them a less-maintenance option.

Features That Make a Humidifier Good For Plants

Humidifiers are made for humans and not plants, so there are a few features that aren’t perfectly calibrated for our indoor gardens. That said, here’s what you should look for when it comes to picking the right humidifier for your plants:

  • Run Time – At least 12 hours of run time and ideally over 24 hours. You don’t want to have to refill it constantly.
  • Simple Design – You’ll be using your humidifier more than most, so it must be easy to maintain and take apart.
  • Small and Attractive – These aren’t necessary features, but I personally like looking at well-designed and compact humidifiers!

These rules go out the window if you are trying to increase the humidity in a larger space like a greenhouse. You should probably go with misters or foggers to humidify a space of that scale.

How to Best Use Your Humidifier

Your garden will not flourish just because you install a humidifier and turn it on. A high humidity environment is equally important.

An environment with proper airflow is essential, especially since many diseases thrive in high humidity. If you allow water to condense on your plants, you will invite leaf spot fungus and all kinds of other diseases.

Here’s a good basic setup for high-humidity environments:

  1. A high-quality humidifier (reviewed below)
  2. A fan to increase air circulation
  3. A tray filled with water and pebbles to catch extra moisture
  4. A temperature and humidity monitor to keep track of levels

Maintaining Your Humidifier

Clean your humidifier completely a few times a month as a good rule of thumb. Because you’ll be using it a lot, you’ll get more salt buildup, fungus, or mold.

You can clean your humidifier by disassembling it and soaking the pieces in a mixture of water and vinegar.

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