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How temperature affects plant growth

Temperature is probably one of the most important factors to consider when building your indoor garden. A rise in temperature can quickly cause damage to your plants or stunt their growth significantly. 

What is the ideal temperature for plant growth?

As a general rule of thumb, the perfect temperature for plants to grow is 21-24 degrees Celsius unless using a CO2 supplementation. When the temperature of the growth area rises to higher than 29 degrees, problems can quickly occur. 

Temperature range for CO2 supplemented grow areas

As mentioned above, if you are using a CO2 supplementation within the grow area, experts suggest you can maintain good growth even if the temperature is up to 5 degrees higher (26-29). That being said, in order for growth to continue, all other factors and conditions within the grow area will need to be maintained within the ideal range. 

How to reduce temperature in the grow area

There are several ways to maintain the ideal temperature for your indoor garden, but the main thing to remember is air circulation. 

Use a larger grow space 

Temperature will rise much quicker in a small, unventilated area such as a closet or indoor greenhouse. By moving your grow space into a larger room, you can quickly reduce temperature back to the ideal state. Using an oscillating fan will also help to maintain the temperature. 

Double up on exhausts 

Rather than using a single exhaust to cool both the grow space and lighting structures, use two. Place lighting within a glass box with an exhaust fan from the light to the window. This will help to remove hot air emitted from the lighting and quickly bring in cool air. 

The second exhaust will be used to cool the actual growth space down. This exhaust can run on a thermostat. Without the heat from the light impacting temperature, the growth space temperature will rise much slower. Therefore, the exhaust will only need to run as and when the temperature rises. 

As heat rises, place the exhaust at the top of the garden, with cool air being brought in at the bottom.

Monitoring temperature with two exhausts will also help plants to maximize growth using CO2.

As a general rule of thumb, fans should be able to remove all the air in the grow space (volume in square feet) within less than 5 minutes. 

Be wary of hot spots 

You might find that there are particular hot spots in your garden. These usually occur directly under lighting. Plants in hot spots are the most vulnerable to temperature-related damage. Use a thermometer and remote probe to monitor the temperature in different areas of the garden. 

Add air conditioning 

One way to ensure a constant stream of cool, fresh air is to add air conditioning. By using air conditioning on one side, and an exhaust fan on the other, you will be able to maximize plant growth and maintain the perfect temperature. Exhaust fans will only then kick into action as and when are needed. Meanwhile when exhaust fans are off, CO2 supplementation can continue. 

Check the nutrient reservoir 

If the reservoir for your indoor garden gets too hot, plants will be unable to take up nutrients. Similarly, if the water is too hot, it will be less efficient when holding oxygen. 

Neglecting the nutrient reservoir, and leaving it to heat up can also cause detrimental impact, and introduce pathogenic micro-organisms – like fusarium and pythium - into the grow area.

Nutrient solution should be kept at a temperature of 18-21 degrees and can be easily maintained by placing the reservoir on a cool surface or worktop like concrete.

Use centrifugal fans 

Both box fans and oscillating fans are required to keep the air in the garden circulated. However, standard exhaust fans typically don’t move air enough. 

Instead, we recommend using centrifugal fans

This type of fan is quiet yet more powerful than other fans on the market – such as squirrel cage fans. They are more expensive, but are much better when using a carbon filter

Maintaining the ideal conditions within your grow area always requires a little trial-and-area. But, the friendly team at Herbal House are always available to help you with any issues or queries you have. Feel free to get in touch