Greenhouse Climate and Humidity Control

Climate and Humidity

Running a greenhouse can be pretty complicated if you aren’t very experienced or know precisely what you’re doing. One of the most finicky things to get the hang of is learning about proper interior greenhouse climate and humidity control. There are different challenges you’ll have to face and overcome, and we’re here to help.

Here is everything you’ll need to know about maintaining greenhouse climate and humidity control to ensure you get the most out of your plants.

What Are Some of The Challenges You’ll Be Facing?

Running a greenhouse and ensuring it’s in working order can be a lot of work, especially when you’re first starting. There are some challenges you’ll have to deal with to get that perfect greenhouse effect. There are four main challenges you will encounter when managing the humidity and climate of your greenhouse.


When the humidity levels are unchecked, and at suboptimal levels, condensation starts to form. When this happens, your greenhouse can quickly become a death house. Condensation build-up on the plants will spread plant diseases, mildew, and other harmful effects. This can cause serious damage. Investing in a good ventilation system for the summer can work wonders for reducing condensation levels.


As you control your greenhouse’s humidity and temperature levels, you will also be managing the transpiration rate. The term “transpiration” refers to the process of the movement of water through a plant to its evaporation through the stem, leaves, and flowers. If you aren’t careful and manage the temperature or humidity incorrectly, you can affect how quickly water evaporates from your plants. This will dry them out.

Consistent Climate

One of the challenges you may face is maintaining a consistent climate throughout the greenhouse. You will need to find an ideal spread of temperature around the greenhouse. You need to equally distribute the heat to ensure there aren’t any hot or cold spots. These can create microclimates within your greenhouse.

The Climate Outside

The world outside your greenhouse can affect what is going on inside. Despite growing within an enclosed space, you will need to keep tabs on what’s going on outside the greenhouse. This will create a balance between the indoor and outdoor air, creating a more stable environment for your plants.

These are problems you may have to deal with through experimenting with different techniques and styles of growing. And you may need to consider other designs for your greenhouse before tackling the job. As you read on, heed the tips we provide as they can help you get around and solve some of these challenges. Plus, you will learn how to create an ideal climate inside your greenhouse.

temperature and humidity in the greenhouse

Insulating Your Greenhouse

The greenhouse is an excellent way to keep your garden growing well all year round, as you will be in direct control of the elements it will be exposed to. This is why greenhouses are so prevalent in cooler climates worldwide, as you can effectively grow crops all year round.

Proper insulation is essential to efficient yields and protecting your plants from exterior forces. These include rain, freezing cold, and biting wind. You’ll also benefit from enjoying more efficient heating with reduced heating bills. Why? Because your insulation will keep the temperature constant for longer periods.

What Are Some Good Ways To Insulate a Greenhouse?

There are several ways you can go about insulating your greenhouse. Online you can find dozens of techniques and different methods of insulation that use varying materials. We’ll cover some popular and effective options you might be interested in.


Polycarbonate sheets have an excellent reputation as reliable insulators. Plus, their usage in greenhouses is no exception. Their benefits include their lightweight but incredible nature, flexibility as a material, and excellent UV-ray resistance. They remain dependable in temperatures as low as -40°F and as high as 284°F.

Heat loss primarily comes from poor sidewall and roof insulation, and polycarbonate sheets offer the perfect solution. The sheets used for insulation come with built-in air pockets. They achieve this by layering multiple sheets together, and it is these air pockets that provide excellent insulation. Twin-walled panels are the most commonly used in greenhouses. However, triple-walled panels are not unheard of as they are in pretty much every way superior, although more expensive.

It’s important to remember that your particular greenhouse will require a level of unique control. Many factors go into finding the perfect interior climate. This includes the outside climate, the ventilation inside the greenhouse, the location and space you have to work with, etc.

When looking at polycarbonate sheets, you’ll notice that they have two different values: the R-Value and the K-Value. These are measurements you’ll want to keep in mind, as they give you an idea of their effectiveness. The R-Value measures the insulating capability, while the K-Value indicates how well the sheet conducts heat. A higher R-Value and lower K-Value means you’ll receive the best in insulation. Be aware that the more insulation a panel may provide, the less light that may diffuse through.

Insulation Seals

Polycarbonate panels are an excellent way to let heat and light into your greenhouse. Heat that builds up over the day will often escape in the night, leading to a cold start the next day. To prevent this, insulation seals provide an additional way to trap heat in the greenhouse when used with polycarbonate sheets.

You’ll find that many greenhouses will have a rubber or silicone seal that prevents heat loss through gaps and holes. Some DIY gardeners may prefer to seal the hole with a tape of some kind. However, this isn’t a wholly effective solution, especially when condensation is taken into account. By using a rubber or silicone sealant, you can find a permanent solution to filling in any issues and providing an extra layer of insulation to help keep the warmth trapped for longer.

With these seals comes the cost of maintenance. You should continuously be checking for any breaks or gaps that may have formed over time and repair them immediately. This will ensure you can maintain the climate you’ve established without too drastic of a change because of an unseen break in a seal.

Foundation Insulation

Often overlooked, the ground is a significant heat conductor that could be a substantial source of heat loss in your greenhouse. When the temperatures outside drop, the ground freezes too, along with the air. This cold can seep into your greenhouse, sapping the heat from inside and cooling the interior climate.

Foundation insulation is quite pricey but can provide a needed level of insulation for a wooden or cement floor. Wood and cement are quite conductive, so heat will very quickly transfer through. If you are looking for a cheaper alternative, dirt, gravel, and peat rock can do a good enough job if layered enough times.

Heating Your Greenhouse Efficiently

Now that you have a well-insulated interior that can hold a reliable temperature, you can move on to heating that interior up. Heating the interior of your greenhouse will give you control over the temperature and climate that your plants will be exposed to. There are a few ways you can go about this. We’ll cover some efficient ways that you may be interested in.

Greenhouse for flowers and plant nursery - temperature measuring

The Timeless Classic of Compost

For many decades, compost has been used in greenhouses to provide a source of heat. If you have ever worked with compost before, you might have noticed that a heap of it produces quite a bit of warmth, especially in winter, where you might even see a bit of steam.

The decomposition of mass in such a concentrated area is what generates this energy and warmth. Thus, you can harness this energy. With a bit of know-how or hiring someone with the skills, you can create a network of pipes that link up to your compost heap. You’ll want to start with around nine cubic feet of compost to start generating enough heat to begin. Bear in mind this size requirement can be taxing on smaller plots of land, so it may not always be practical.

Using a Heater

Of course, one of the easiest methods is to invest in a heater for your greenhouse. This comes with some advantages, with direct control over the heat generation inside being the most significant.

Of course, heaters can get quite expensive, especially taking into account the cost of running one. If you think of a heater and you’re already getting dizzy from thinking of the electricity bill, worry not! While electric heaters are perfectly viable, paraffin heaters are a much cheaper alternative that are just as simple to use. Their only drawback is that they aren’t too suitable for larger greenhouses. Either investing in more heaters or larger heaters may be a way to circumvent this, but you risk unevenly distributed heat.

Solar heating can also help solve the issue of a power bill. Of course, you will already be using solar energy through the transparent walls and roof. But we mean to use solar batteries to power whatever heaters you may have to cut down on energy costs.

Some Help From Animals

If you’ve spent some time on a farm, you’ll likely be aware of the amount of heat generated by animals. A greenhouse is no barn, and you can’t invite cattle inside the greenhouse. However, you might find that smaller animals can be great helpers.

Chickens are prime examples of animals that don’t take up much space and provide a few benefits for your greenhouse. They can provide body heat and carbon dioxide to benefit the plants and eat the insects that may have snuck in. In return, the greenhouse acts as a warm shelter and a safe location to keep their eggs. You will, of course, have to look after the animals. The added responsibility may not be what you’re looking for.

Thermal Mass

One of the best ways to heat a greenhouse for extended periods is to take advantage of thermal mass. By taking advantage of items that can store heat and release it slowly over time, you can create a sort of thermal battery. This can keep your greenhouse’s temperature pretty constant and stable.

You can achieve this by using water barrels, compost, stones, or even bricks. Any darker, heavier objects that can capture and retain heat, slowly releasing it over time will work. Water barrels are pretty popular for this purpose, as they have a high capacity for warmth and are easy to acquire. Just find some old barrels, fill them with water, and place them strategically to distribute the heat.

Air ventilation system blowing fresh air in greenhouse

Keeping Your Greenhouse Cool

When the sun is out for longer and outside heats up, it’s very easy for your greenhouse to overheat. This means taking some measures to provide some cooling for your greenhouse. It will also give you more control over regulating the temperatures. These methods will also help you control the humidity by providing constant airflow.

Natural Ventilation

The quickest and most efficient way to cool your greenhouse is to let the excess heat out. By installing a ventilation system in your greenhouse, you can take advantage of natural ventilation by allowing a draft to waft through and giving a channel for the heat to escape through.

For the most efficient cooling, install the vents higher up, ideally in the roof. As the heat rises and accumulates at the ceiling, it will find its way to the vents and escape, allowing fresh air to flow in.

Store-Bought Ventilation

Using fans can be an excellent way to provide additional cooling for your interior. While opening some vents, doors, or windows may typically suffice, a fan may be required in hotter climates. You can find fans of all sizes and strengths available. Just remember that your goal is to cool an entire greenhouse, which is designed to trap heat, so an office fan won’t do.

Instead, look for industrial-grade fanning systems that won’t be intrusive to install nor be taxing on your bill. Staging fans can help significantly with this, as you can set parameters for when the heat begins to ramp up. If you’re really on a budget, a portable evaporative cooler can do the trick for smaller greenhouses. It works by reducing the humidity and cooling the area.

Come To Grips With Your Greenhouse

Now that you have some idea of how you can better approach controlling the climate and humidity of your greenhouse, experiment with what works in your greenhouse. Unless you’ve worked off of another person’s set of instructions, your greenhouse will be at least somewhat unique. So it’s always best to see what works best for your particular case. That being said, what we’ve discussed here is so widely applicable that you’ll have learned something that can help you on your greenhouse growing journey.

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