You just survived the super long and super cold winter with these amazing 11 tricks for heating a greenhouse and are fully ready for a spring/summer season.
What temperature is too hot for a greenhouse?
It can be very tricky to maintain the optimal temperature in your greenhouse with the night temperatures dropping as low as 5°C and raising to 20°C during the day.
In this case many people close the doors and vents at night time which increases the temperature inside the greenhouse to whooping 35°C in a day time. It is equal to 90°F which is too hot for a greenhouse.
As you probably know that’s life threatening for the majority of plants. So, you need to keep the temperatures down when it’s hot outside.
Luckily, I am going to share with you my top greenhouse cooling ideas.
Let’s get started!
I would suggest to try all of the traditional ways of keeping your greenhouse cool in the first place.
By the traditional ways I mean the cooling options which don’t require any electricity and are not automated.
These ways are: ventilation, shading, damping down and watering.
How do you cool down a greenhouse?
Step 1 – Ventilate your greenhouse
Ventilation, in other words, is an air circulation created when you are opening doors and vents in your greenhouse.
A good circulation of air provides a better temperature. How? The vents at the bottom of the greenhouse let the cold air in which then heats up and exits through the roof vents.
Step 2 – Shade a greenhouse
Shading is a great way to decrease the temperature inside the greenhouse by blocking some of the sun rays.
There are a few types of shading which you can use: shade paint, shading blinds and a shade cloth.
To find out more about the pros and cons of each of them you need to go to this article.
Step 3 – Damping Down a greenhouse
The drier the air the higher the temperature inside your greenhouse. That is why you need to pay extra attention to humidity.
The best way to keep the levels of moisture in the air up is to wet hard surfaces inside the greenhouse. Wet paths and staging three times a day and you will see the difference.
Step 4 – Watering the plants cools them down
You don’t need to forget that plants can cool themselves down as well. In the process known as transpiration. All you need to do is to water your plants REGULARLY.
I have talked about these four greenhouse cooling ideas briefly, but if you want to find more information – read this article.
Now, let’s talk about some of the more advanced and automated options.
Step 5 – Using Thermostatically controlled exhaust fan systems
If you are not relying on the roof and side vents that much, you can invest into a fan system. It doesn’t use much electricity either.
The huge benefit is that this fan system can be thermostatically controlled. Installed in the system thermostat automatically adjusts a fan to the changing temperatures.
All you need to do is to set it up to a certain temperature, usually, around 75-80°C .
Similarly to a traditional ventilation with side and roof vents the air inside the greenhouse will change every minute and a half or two minutes.
The exhaust fan system consists of a fan and shutters. To ensure that a fan system operates efficiently you need to allow an intake of fresh air from the outside of greenhouse through the shutters.
For the best results install these in the opposite end of the greenhouse. I found this great fan ventilation system which is powered by a solar panel.
It is a very environmentally friendly option. Moreover, because the fan is working only when the sun is shinning it will stop once the sun is weak ensuring that your greenhouse stays warm.
Step 6 – Using Greenhouse Misting System
Greenhouse misting system is an advanced alternative to traditional damping down. Instead of you manually wetting the floor inside the greenhouse an automated system will do it for you.
However, the main principle is the same. It is aimed on raising the humidity levels of your greenhouse.
Moreover, evaporation of moisture has proven to be much more effective in cooling a greenhouse rather than shading and ventilation.
When water evaporates it uses heat to change from liquid to gas state. In conjunction with good air circulation from the fans and vents the evaporation will be higher. As a result, your greenhouse will be cooler.
When calculating the amount of moisture required to cool your greenhouse you have to take into the account following factors.
Consider the amount of shading and ventilation provided, take a not of the local climate and keep in mind the daily weather alterations.
The reference amount for a standard greenhouse is 1-2 gallons of water every hour per each 10 square feet of floor area.
A misting system automatically disperses the mist in equal quantities. The plants can easily absorb the mist without being soaked in water.
The location of nozzles plays a big difference. It is better to install them under the benches and in front of the shutters at the bottom of the greenhouse which intake a fresh air.
Now you know the importance of the evaporation and we are going to talk in which other ways it can be used to cool a greenhouse.
Step 7 – Using Evaporative Cooling System for Greenhouse
Evaporative cooling is a cost effective and a very efficient way of cooling a greenhouse in dry climates.
Similarly to the misting system, evaporative cooling is based on the evaporation of water.
There are two types of evaporative cooling systems: evaporative cooling pads and high-pressure fog systems. Sometimes, a combination of both can be used inside a greenhouse.
What is Evaporative cooling pad?
Cooling pads are made of the corrugated, environmentally-friendly paper material. These are treated with anti-rot and wetting agents.
The pads should be installed along the side or end of the wall opposite to the mechanical fans.
Apart from the cooling pads you will need to install overhead water supply pipe, gutter which collects excess water, sump tank, pump, pipping and control.
Also, you can control the system by using a mechanical thermostat or an environmental computer.
How do evaporative cooling pads work?
How does it work? Basically, the water is pumped over the pads which are pulling hot air through gaps at one end of the structure.
The hot air is used to evaporate the water into the air and cooling down the greenhouse.
The pads are relatively cheap and affordable. You might need to replace them every year or so.
The main concern should be with the costs of running water into the pads.
High-pressure fog systems for greenhouse
You can use a high-pressure fog system in both naturally (roof and side vents) and mechanically (fans) ventilated greenhouse.
Fogging systems are less expensive than pad cooling systems because these are using less water.
Similarly to the misting system, to work effectively, fogging system should be installed in conjunction with several factors.
Greenhouse location, changes in the weather conditions and ventilation rate should be considered when installing a fogging system.
How do high-pressure fog systems work?
The working principle is similar to the misting system. The misting nozzles or sprinklers are installed on the roof of the greenhouse.
These are then fogging water on the crops in your greenhouse. Also, in comparison to the cooling pads system, fogging system nozzles can be placed around the greenhouse. This results in more consistent and equal cooling pattern.
However, be careful with both misting and fogging systems. Excess of moisture can provoke fungal and other diseases!
REMEMBER! Evaporative Cooling and Misting will only work in dry climates!
These are some of the most common ways of cooling your greenhouse. I always have my eye on new greenhouse cooling ideas, so if you have some to share, please don’t hesitate to contact me 🙂
