How Warm Should A Grow Room Be?

 During the early stages, such as the germination and seedling stage, the ideal temperature range is 75-85F / 24-29C. The ideal temperature in the vegetative stage is around 70-85F / 21-9C. Once the plants begin transitioning into the flowering stage the ideal temperatures are between 60-80F / 16-27C. Cannabis is a resilient plant that can withstand multitudes of conditions. Anyhow, if the plant is not at ideal temperatures it is likely to grow slower and to yield less.

How Warm Should A Grow Room Be?

What Happens If A Grow Room Is Too Hot?

Higher temperatures are less of your concern. It isn’t as dangerous as leaving your plants in a colder environment. But high temperatures could also inflict irreparable damage to your plants. Temperatures above 86F or 30C lead your plants to grow slower. The enzymes responsible for photosynthesis don’t work as expected in warmer conditions.

Stunted growth is one of the most noticeable effects of high temperatures in cannabis plants. Apart from that, pests and diseases like spider mites and white powdery mildew tend to thrive in hot conditions. Warmer conditions also tend to make water evaporate quicker. Nutrient burn could arise when your plant’s roots can’t absorb nutrients in the soil. Stagnant nutrients in them could cause damage to the roots and the foliage.

Plants growing in hot and humid conditions without air circulation can develop bud rot and mould that causes stress to them. If you fail to take care of these, all your efforts will go to waste.

What Happens If A Grow Room Is Too Cold?

Colder temperatures can be brutal towards plants. Unlike in higher temperatures, colder temperatures could shock and kill plants. The rate of photosynthesis can also reduce because of cold conditions. Slower photosynthesis means that your plants will grow at a slower pace, much like in hot conditions.

If you use HID or HPS lamps It is best to have the lights on during the night as it is colder during those times. Remember that plants need light cycles but certain types of lights add more heat to them. To offset that, turn the lights on at night and balance off the night’s coldness.

There are instances wherein plants grown in colder environments develop blue or purple-hued buds that look great during harvest. But this still depends on which strain you have. Most of the time, Indica strains grow to have those hues as they are native to mountains with colder environments.

How Do You Measure Temperature In A Grow Room?

Monitoring temperatures in a grow room benefits a grower by giving a heads up on what a plant needs. It’s always best to be one step ahead in growing cannabis.

But how do you measure the temperature in a grow room?

Thermometers still get the job done. But now that there are digital and analog variants, it is easier to calibrate these tools to measure heat in the environment. It is not only cheap to buy, but monitoring is easy. Hang it on the wall and wait for it to read the results to you.

Remember to take temperatures under a shade. It will always be warmer if the area you’re measuring is under direct sunlight or grow lights. You should measure in various places within the grow room to get a clear insight into how it is going.

What Is Humidity And Relative Humidity?

Humidity is a measurement of how much water vapor is in the air. However, it is good to remember that warmer air holds more water vapor than cold air. Meanwhile, relative humidity is a measurement of how much water can air hold at a given temperature.

Once relative humidity reaches 100%, air starts to release the water it can’t hold. Later on, the water will condensate to fog, morning dew, or rain. The relative humidity for plants can vary. Plants that grow in hot, tropical areas adapt well to higher relative humidity.

As a rule of thumb: Indicas prefers a colder, less humid environment, while Sativas prefer a warmer and more humid climate. 


How Does the Temperature affect the Relative Humidity?

Temperature and relative humidity are strongly affecting each other. Warm air holds more water vapour than cold air. Therefore, the increase of a grow rooms temperature is usually associated with an increase in absolute humidity.  Humidity causes damage to plants. Moulds, mildew, root rot, and pest infestation are only a few effects of too much water vapour in a grow rooms air.

Apart from that, since warmer environments contain more water vapour, it forces the plants to absorb water through their leaves. Water absorption through a plant’s leaves can be an issue since plants need to soak up water from their roots to acquire the soil’s nutrients. If they only absorb moisture through their leaves, it will result in nutrient deficiency. 

How Do You Adjust Temperature In A Grow Room?

Maintaining temperatures and humidity at optimum levels can be a struggle for novice growers. Always remember the rule that warmer temperatures hold more water vapour. Let this serve as your guide in balancing temperatures and humidity in your grow room.

Increasing airflow within the grow room will allow cooler air to settle in. Using fans and good exhausts could circulate air within the grow space. Take advantage of the cold nights by establishing a light cycle that lights only turn on during the night. In this way, you get to lessen the colder temperature by adding heat through grow lights. But in a way, you don’t add more warmth since the cold night balances it all out too. For a more advanced cooling method, installing air conditioners would also help. Take note that this could increase your electricity bill.

If your grow room is too cold and your grow lights can’t make up the difference, or if you are using LED’s, you can simply turn on the heater of the room.

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