What are the optimum humidity levels for indoor plants growing?
If you want to grow sticky, high-potency buds, your indoor plants will demand attention to its many needs.
One need of the growing indoor plants– that is commonly overlooked – is humidity.
Believe it or not, humidity is actually very important to your plant! Humidity will help determine your plants resilience against mold/mildew in addition to how much your plants need to drink. Getting it just right can improve plant growth and increase your yields.
When we talk about humidity, we usually mean relative humidity (RH), which is the ratio of partial pressure of water vapor to the maximum vapor pressure of water at the same temperature. You get the whole idea when knowing the basic principle that warm air holds more water vapor than cold air. This is one of the reasons why it’s necessary to extract a lot of warm air from our grow room, and ideally allow cool air to enter – warm air simply holds too much water vapor in it.
Effects of Poor Humidity Management
White Powdery Mildew
White Powdery Mildew is a fungal disease that young indoor plants flourish in high humidity environments. Luckily, you can stave off WPM by making sure there is proper airflow in your grow area; a small oscillating fan – even on the low setting – works wonders.
Bud Mold or Rot
Beacuse of your poor humidity management, bud rot or mold will be discovered. Imagine harvesting a huge, dense main cola from your plant only to see the insides are totally white or brown with mold. In this condition buds are unusable and 100% should be thrown away.
Nutrient Problems
Humidity is a factor that partly determines how much your plants will drink. If the air is dry, your plants will tend to drink more at their roots. If they’re already drinking more due to high temperatures, low humidity can cause them to drink a lot of water through their roots and uptake too-high levels of nutrients. If your plant takes in more nutrients than the plant can use, the leaves will begin to show yellow or burnt tips, which is the result of nutrient burn. Sometimes too-low humidity can cause other apparent nutrient problems.
Slowed Growth
Indoor plants love higher humidity when they’re young, and lower humidity when they’re mature. To be frank, if they’re not getting these conditions, they may not be growing nearly as fast or healthy as they could.
Now we know why we need to manage humidity when growing indoor plants, but we may not know what humidity you are aiming for. So, What are the optimum humidity levels for indoor plants growing?
Here are some basic “rules of thumb” you can follow:
- Seedlings and clones like RH levels of 65–80%. Remember, these young, fragile plants have weak root systems. By increasing humidity levels, you’ll allow them to take up more water from the environment and focus on developing strong roots. At this early stage, you’ll want to keep temperature levels at around 25°C during the day, and around 21°C at night (77°F and 70°F, respectively).
- Vegetative plants, on the other hand, tend to prefer moderate humidity levels. There’s no exact figure to follow here, but you’ll want to stick somewhere between 55–70% depending on the strain. Temperatures should sit between 22–28°C (71–82°F) during the day and roughly 18–24°C (64–75°F) at night. Vegetative plants have strong root systems and will absorb more water from the soil, which is why most growers drop humidity levels slightly during this stage.
- At the early flowering stage, most growers agree that plants benefit from lower humidity levels. Again, there’s no ideal figure to aim for, but many will stick between 40–50%, occasionally pushing to roughly 55%. You’ll also want to drop temperatures to about 20–26°C (68–78°F).
- During the late flowering stage, try to drop humidity to about 30–40% and keep temperatures around 18–24°C (64–75°F) during the day, followed by slightly cooler nights (16-20C in the last few nights).
Adujusting humidity levels
We’ve got a pretty good idea on humidity levels we aim for. Now it’s time to get to the practical part, and to find ways to bring things back in balance when they’re not.
Lower humidity
- Run you existing tube vent on higher velocities or upgrade (air exits tent AND the room it is placed in!)
- Increase fresh/cool air supply (e.g. active air intake by 140mm case fans for PC’s)
- Try to water your plants right after lights are switched on
- Spend money on a decent sized dehumidifier (the small ones can’t hold enough water)
Raising humidity
- Manually increase humidity levels with a spray bottle (It won’t last long)
- Keep the surface of the soil moist, but not wet
- Hang wet towels/cloths in your grow room or put open water containers in it
- Invest money in a humidifier ( highly recommend Eco Farm Humidifiers) with a large water tank (small ones demand constant refills)
Humidifier is an efficient way to add additional moisture to the air and thus increase your room humidity quickly. Here we give two for your consideration which we think both useful but cheap.
ECO FARM Hydroponics 8L Capacity Air Humidifier Grow Room Tent
Increases humidity in dry living spaces and grow room.
-Removes unpleasant odour and other smell.
-Removes dust and indoor air pollution.
-Disinfects and deodorizes indoor air. -Creates clean,hygienic and bacteria-free air.
-Place: Applicable for room size: 30m2.
-Working time: 14-28 hours.
-Caution: Better use clean water.
-Better switch off when power off.
-Waterless automatic protection.
-Mist-out mouth rotatable at 360°C.
-Chrome decorated switch for Mist Adjustment, Time setting and Night Light.
-Removable water tank with a wide mouth for easy filling.
-Low noise.
ITEM SIZE:256*256*330mm
NET WEIGHT: 2.0kg
GW:2.6kg(WITH BOX)
TANK CAPACITY:8.0L
MIST VOLUME:300-350ML/H
RAW MATERIAL:ABS+PP
Pure Enrichment MistAire Ultrasonic Cool Mist Humidifier
- ULTRASONIC COOL MIST TECHNOLOGY: Safely moisturizes the air for up to 16 hours of continuous operation so you can breathe easy and get more restful sleep | High and low speed settings make it easy to adjust mist direction and speed to fit your comfort level
- 1.5-LITER WATER TANK: Provides ideal coverage for bedrooms, offices, and other medium-sized rooms
- OPTIONAL NIGHT LIGHT: Offers soothing glow for maximum relaxation
- AUTOMATIC SHUT-OFF: Turns humidifier off when water level is low or the water tank is removed
- WHAT YOU GET: Humidifier, AC power adapter, disk cleaning brush, user manual, industry-leading 2 Year Warranty, caring customer support 7 days a week, and the peace of mind that comes from a trusted brand with millions of customers worldwide.
