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Humidity Goals For Grow Tents 

cannabis grow tent humidity

When you’re growing plants in a grow tent, humidity always plays an important role. Humidity percentages should be monitored night and day as fluctuations can take place. A good humidity goal for home growers using grow tents is 50 – 55% RH (relative humidity). One of the reasons 50 – 55% RH is recommended is that it actually helps prevent powdery mildew and other fungal plant diseases. Powdery mildew spores do not survive in this range. Ultimately this helps protect the plant from potential harvest-killing infestations.

You can make it hard for powdery mildew to infect your plants by keeping your humidity at 50 – 55% RH. Although cannabis plants may respond well to 65% or 70% in the veg phase of growth, these percentage levels would indicate the grow tent environment is conducive to powdery mildew.

TIP: Overall, fluctuations of humidity over 10% are frowned upon and to be avoided. 

If the humidity is too high, plants can have trouble uptaking nutrients. This can lead to stunted growth or deficiencies. If the humidity is too low, the plants will suffer as they need moisture.

Sometimes you have to increase humidity up in your grow tent. Sometimes you’ll have to decrease it. Growers in dry climates often need to add moisture in their grow tent with humidifiers. However, growers in humid climates need the opposite. They’ll need dehumidifiers. Nevertheless, many growers live in climates that require them to use both humidifiers and dehumidifiers at times. Ideally you should purchase high quality ones because the small inexpensive ones will break, or have limited effectiveness.

Common Humidity %  Recommendations For Cannabis Cultivation

Many humidity recommendations for gardening cannabis look similar to the percentages below.

  1. Seedlings/Clones Humidity: 70 – 75%
  2. Veg Humidity: 50 – 70%
  3. Flower Humidity: 40 – 50%

While these humidity goals suffice, they do not help you prevent powdery mildew, a very common problem for indoor growers growing in grow tents. A humidity goal of 50 – 55% however does. Powdery mildew equates to a lost harvest, so avoiding it is crucial.

Understandably at times humidity may climb to 60% + or 70% + if you are rooting clones. Beware if you do though, since you’re technically creating an environment conducive to powdery mildew. The sneaky thing about powdery mildew is that once you’re infected, you won’t know it right away. Once powdery mildew spores infect the surface of a plant, it takes a few days for the white powdery mildew globs to be visible to the naked eye.

Don’t be blindsided, be prepared!

While you’re getting the humidity % dialed in, another way to be prepared and prevent powdery mildew is to use the Airo Home Hobby air purifier. These air purifiers will suit a grow tent at least 4 x 4 ft, up to 12 x 12 ft. Just hang Airo Home Hobby in your grow tent, or hang it in the room your grow tent is set up in. If you’re living in an area with lots of instances of local powdery mildew, blight, botrytis, etc., use Airo Home Hobby as your best proactive defense against these highly contagious plant diseases. Airo Home Hobby works by destroying powdery mildew spores on a subatomic level using proprietary technology based on PCO (photocatalytic oxidation) technology. Keep it running in your grow tent 24/7. Followed by that, you can use foliar sprays that act as a powdery mildew preventative like Serenade Fungicide.

Lastly, consider the following 5 tips to keep your humidity goals on track.

  1. Pay attention to your hygrometer readings, including the daily high’s and low’s. Most hygrometers feature a high/low function.
  2. Purchase more than one hygrometer to ensure you are getting accurate readings.
  3. Do not water your plants at night as it causes humidity to rise significantly. Always water your plants in the morning time when they wake up.
  4. Ensure good air flow in your grow tent. An exhaust or intake fan, and one or two small clip-on fans are enough to accomplish good air flow in a grow tent.
  5. You can open grow tent doors (unless you’re in FLOWER during dark time) to help with airflow and humidity too. While it’s common to keep the grow tent zipped up, sometimes you need to unzip it and keep it open.

Do not underestimate humidity as the crucial factor it is. Put proactive measures into place and you’ll manage and control it with success. And your plants won’t suffer.

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