Keeping Your Grow Room/Greenhouse At The Best Temperature

Keeping Your Grow Room/Greenhouse At The Best Temperature

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Temperature is often one of the overlooked aspects of indoor gardening. It’s important to understand the role temperature plays in a plant’s growth. I certainly didn’t realize the effects of temperature when I started hydroponic gardening or just how easy it is to monitor and control the temperature in my grow room.

Here are some things I’ve learned about temperatures’ effect on plants and how to heat/cool my grow room.

How Does Air Temperature Effect A Hydroponic Garden?

Plants in hydroponics and dirt react the same to air temperature.

Plant productivity can slow- Plant growth slows drastically in colder temperatures. In temperatures that are too warm, fruits may not set.

The amount of pests can grow- Pests prefer a warmer climate. Keeping your grow room too warm could be making it a suitable environment for pests to infest.

Plant size can be affected- Temperature also has an effect on the size of your plant. In nature, plants experience a temperature change from daytime to nighttime. This actually assists with the plant’s growth. It’s recommended to drop the temperature by 10-15 degrees during the lights-off period.

You can use this to your advantage to manipulate how big your plants get overall. Providing a temperature variation of less the 5 degrees will cause plants to produce less space between nodules, meaning plants will grow smaller and more compact.


What Is The Best Temperature For Indoor Plants (Shoots)?

Crops are usually placed in 2 categories when it comes to temperature, cool weather, and warm weather. As with other aspects of the garden you should match your plant with the environment the plant would experience in nature.  Do some research on the variety of plants you’re growing to find the best temperature to keep your garden.

I usually keep my cool weather crops somewhere between 55 to 65 degrees and keep my warm weather crops somewhere between 75-85 degrees.

Ways To Heat A Garden Grow Room/ Greenhouse

Electric heat- While the startup is lower for electric heat, it’s typically more costly over time and can be inefficient. With that being said, if you have a small area that only needs adjustment every so often, electric heat is probably the easiest way to heat your grow room.

Propane- Propane is an efficient way of heating a grow room. There are attachments you can hook up to propane tanks for small rooms or furnaces to heat whole greenhouses. Personally, propane makes me nervous.

Wood stove- Depending on the area you’re growing in, wood may be a relativity low-cost way to heat your grow room or greenhouse. Wood heating could potentially be the most reliable, as you don’t run out of energy as long as you have wood. Wood heating is more difficult to regulate.

Keep in mind though that a wood stove takes the humidity out of the air.

Grow lights & equipment– If growing in an enclosed area, the heat from your grow lights and equipment may be all you need to keep your grow room warm enough.

Ways To Cool Your Garden Grow Room/ Greenhouse

Air conditioner- Adding an air conditioning unit is the simplest most accurate form of cooling your grow room or greenhouse to the best temperature.

Adding more/ larger fans- Depending on the situation, adding more fans or larger fans may be all you need to cool down your grow room. Adding a bigger exhaust fan will suck our warm air faster.

Evaporative cooling- Evaporated cooling is a process that uses evaporation to cool the air. By pushing air through moisture it causes evaporation and the air temperature to lower. There are fans that use evaporative cooling for smaller areas and evaporative coolers for large areas.

Change your lighting- Cooling your grow area may be as simple as changing out your light source. While HPS lighting is great for growing, they create a lot of heat. Switching to LEDs, or even fluorescent lighting if you’re growing small leafy greens, will cool down your grow room.


Temperature plays a large role in plant growth and how they produce. Planning ahead of time and controlling the temperature will allow your garden to produce at its highest.

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