How to Control Humidity and Temperature in Microgreens

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Humidity is a necessity for plants and microgreens to thrive. If you have ever entered a botanical garden or a greenhouse, you may have felt the sensation of hot and humid air. Being able to control the humidity and temperature can be the reason for success or failure with your growth. Growing microgreens inside your home, it can be tricky to know what the optimal conditions are. How do you control the humidity level, and how do you keep the temperature just right for your microgreens to grow healthy? 

There are different ways to control humidity and temperature in microgreens. Providing moisture with the help of a humidifier when the air is dry or using a dehumidifier when there is too much moisture. Another good option is using a ventilation system that can bring in fresh air. 

At the end of the day, the best approach depends on your environment and growing conditions. 

We will take you to through different ways you can apply to control humidity and temperature. We will also provide you the right measures and explain the reasons why they are essential for successful growth.

What should the humidity be for microgreens?

Depending on the stage of the growing cycle, the ideal humidity level will vary slightly. 

Humidity levels are generally higher in the summer and lower during winter months. Factors such as season, weather, and where you live also have an impact. Most microgreens grow well with a humidity level of 40-60%. If you have higher humidity, you may experience that your crop will start to grow mold. If it’s lower, your microgreens may dry out and wilt.

The humidity level in the average home is around 40-50%. It’s the level where most of us feel comfortable. If it’s higher or lower, it may impact your growth of microgreens. Some help may be necessary to provide optimal growing conditions. 

What is causing humidity?

First, let’s understand what it is. Humidity refers to the amount of moisture in the air versus the total amount of moisture that it can hold. We experience condensation and dew when the humidity level is over 100%. It means that there is more water than what can be held up by the air. 

There are different reasons you can experience high humidity in your home. It can be because of building-related causes, broken AC, overwatering of plants, or even due to your daily activities. Showering, cooking, exercising, all of these day-to-day activities create moisture and humidity.

Why is humidity important for growing microgreens?

We know that too much humidity in a home is not healthy. It can pose health risks as the mold starts to grow. On the contrary, if the air is dry and there is low humidity, it can be uncomfortable. It’s equally important for plants and microgreens.

Microgreens need a certain level of humidity as they breathe carbon dioxide from the environment through their leaves. It means that they absorb moisture in the air, which they need for their growing cycle. 

When the air is too dry, it will make them dry out as they will lose more water than they can retrieve via their roots. On the contrary, if the environment is too humid, the microgreens can also fail as it allows them to grow mold and other diseases.

Humidity level and temperature for the different growing phases

Same as plants, microgreens undergo a crop cycle. The first step to growing microgreens is planting the seeds. The germination happens during the blackout period. Not long after the microgreen seeds have germinated, we bring them out in the light so they can begin to grow its first true leaves. Finally, there is the harvest. 

These different phases require some differences when it comes to humidity. Although many seeds are capable of germinating and growing without much help, if we don’t create an optimal environment, then microgreens tend to germinate slowly and unevenly.

The right temperature

It’s equally important to have the right temperature as it is to have the optimal humidity level. In general, your microgreens will grow perfectly well at room temperature around 70 degrees F (21 degrees C). For microgreens, as their growing cycle is short, you don’t need to worry about adjusting the temperature based on the type you are growing.

Conditions during seed stage (the blackout period)

Seeds essentially need three things to germinate. Those are oxygen, moisture, and the correct temperature. If you don’t give them these, you may experience that some seeds will be dormant until they are in the right conditions and some may sprout but later perish.

All seeds need correct moisture to start the processes leading up to germination. During the germination process, the seeds can benefit from a humidity level of around 50-80%. You can create this by placing the seeds in a closed space using different methods. 

You can cover them with a moistured paper, put a lid on a tray, or use a propagator. A propagator is a covered container filled with medium, used for germinating or raising seedlings. It creates a “greenhouse” atmosphere for the seeds to grow.

Using a propagator ensures your seeds are consistently moist. It creates the perfect conditions for growing microgreens from seeds, keeping the soil moist and the air warm. 

Propagators come in different versions. The more simple and cheaper version is the propagator with vents. With a clear dome having vents, you can easily control humidity while allowing maximum sunlight to your seedlings. Depending on your home conditions and if you want to have an even more controlled environment, you can get the propagator with regulated heat mats.

Conditions for the light period

After a few days in the dark and humid environment, the seeds will have germinated. Then you bring them out in the light. During this phase, they will absorb more water from the medium as they grow strong roots. When they have reached an inch to an inch-and-a-half in height, you can drop the humidity level to around 40-60%. 

Provide them ideally with natural light, remove the dome, and give them fresh air. Your microgreens will grow healthy if you keep them in stable conditions and not have constant huge swings in temperature and humidity levels. 

As mentioned, if you expose microgreens to high humidity they tend to mold. Keep your medium continuously moist but not soaked. Overwatering can as well cause a humid environment. 

How can I measure the humidity level?

To measure humidity you can use a hygrometer. This device, which looks like a thermometer, measures the amount of water vapor in the air. If you find that your microgreens are not growing healthy and know that you have issues with humidity for whatever reason, this can be a small investment to help you get the conditions right. 

A hygrometer costs around 15 dollars. It’s a good investment for keeping your microgreens under control and growing in a healthy environment.

How do you add humidity to microgreens?

If you are suffering from too little humidity and dry air, there is help. In colder climates, during winter, you may experience that the humidity level drops in line with the temperature. During periods of extreme heat, we use air-conditioning that also has a drying effect on the air. In any of these circumstances, there are methods you can use to add moisture and humidity. 


To add humidity to your microgreens you can use a simple method which is to mist them with a fine spray of water. You will add moisture to the growth. However, the downside is that the effect is only temporary. The water will vaporize and you will have to mist often to keep them moist. If you are keen to look after your microgreens frequently, this is an easy and cheap solution.


Another option is to use a humidifier. It’s an electronic device that adds moisture to the air. You fill the machine with water and it creates steam to increase the humidity level in the air.

The benefit of this machine is that it can provide a steady and continuous level of humidity. Its capacity differs depending on the machine’s water tank size.

The downside of using a humidifier is that it requires some work. Dirty reservoirs and filters can develop bacteria and mold. So you must maintain the machine by regularly change water and filters. If you are up for that, it’s a great solution.

How do you remove humidity?

If you are suffering from too much humidity, there are ways to reduce it. First, you want to consider where you are growing your microgreens. Some rooms such as kitchens have higher humidity levels. Chose a place that can provide the best conditions.


One option to remove humidity is by using a dehumidifier. It’s a device that extracts water from the air. The good thing with using a dehumidifier is that it removes excess water but it doesn’t impact the temperature.

Ventilation system

You should also consider checking your ventilation system. It can be enough with a fan to help control the temperature & humidity level in the grow area. Depending on the level of humidity you have, using a proper ventilation system can vent out humid air, and replace it with fresh air. 

When is the best season to grow microgreens?

We have talked about the impact of humidity and you might wonder if season-wise there is a better option. We don’t believe there is a better season to grow microgreens. You can grow them all year round. 

As microgreens don’t require to be grown outside in a garden or a greenhouse, you can provide the ideal conditions all year inside your home. 

Where is the best location to grow microgreens?

The best location is where you have room to place your microgreens. It can be in your kitchen or any other room or even your basement. It depends on your ambition. By this, we mean, if you are planning to grow on a larger scale or if you just want a few trays. 

If you are planning to grow commercially, you may want to use a larger space such as a basement to accommodate numerous trays. If it’s on a smaller scale you can grow in any room as long as you can provide the right conditions for temperature, humidity, and light.

As mentioned, remember that rooms such as kitchens normally have higher humidity levels, so you may need to use a dehumidifier to get the right conditions.

What problems are caused by wrong humidity and temperature?

When your microgreens don’t grow in the right conditions you may end up with a growth that doesn’t give you the results you had expected. The most common problems you will face are that your microgreens will grow mold, they will be turning yellow and they may even start to smell. You can also experience that your seeds are not germinating and that you end up with an uneven crop.

RELATED: 8 Common Microgreen Problems and How to Fix Them


To grow microgreens, you must have the right level of humidity and temperature. That is 40-60% humidity and room temperature. If you don’t look after this, you may end up with microgreens wilting and growing mold. 

It can seem challenging at first to keep it all under control. But with this guide, we have given you some tools to get some basic conditions right. 

Remember, the figures we have listed in this article are guidelines. You have to try what works for you. One of the benefits of growing microgreens is that the growing period is short. You don’t have to wait long until you realize if you have to adjust anything to achieve better growth. If you have faced problems due to humidity and temperature, try applying the measures we have described. Before you know it, you will have found a way to control the humidity and temperature in your growing area.

Happy growing!

Microgreens Corner
Microgreens Corner
We are Janette & Jesper, and we love microgreens.


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