Humidity

Understanding humidity is key to keeping your houseplants thriving instead of just surviving.

Many tropical plants come from lush environments where the air is packed with moisture, while many succulents are adapted to life in low humidity. Some of the more forgiving houseplants are highly adaptable and tolerate a wide range of humidity levels.

High humidity (60% - 80%+)

High humidity replicates dense tropical rainforests, cloud forests, and riverbanks. Air at this level can feel thick, carrying a heavy amount of moisture vapor.

Plants that require high humidity usually have thin leaves or other sensitive plant parts that dry out quickly in standard room air. Because maintaining 60% to 80% humidity in an open room is difficult or nearly impossible in standard homes (and can cause damage like mold or peeling wallpaper), enclosed environments are usually necessary.

Tips for maintaining high humidity

• Use an enclosed environment.
  For plants that require stable, consistently high humidity (about 80% or more), use glass terrariums, cloches, or closed glass greenhouse cabinets to trap moisture from soil and leaves without raising humidity in the rest of your home. Just make sure there is some air exchange as well.

• Take advantage of bathrooms.
  For plants that enjoy high humidity but don't strictly need it, place them in bathrooms with bright windows, where temporary steam from daily showers naturally raises the moisture level. Keep in mind that this humidity level may fluctuate throughout the day.

• Add micro-fans in enclosures.
  High humidity without air movement can encourage issues such as rot. When using greenhouse cabinets or terrariums, install small USB fans to keep air moving gently around the leaves.

• Shield from drafty vents.
  Keep delicate species far away from heating vents, radiators, and air conditioners, which quickly strip moisture from thin leaves.

Normal humidity (40% - 60%)

This is the standard range for average living spaces and serves as the sweet spot for many popular houseplants. It is also the ideal level for our comfort.

Most easy-to-care-for tropical houseplants, as well as adaptive dry-climate plants adapt well to this middle ground. Their leaves can manage standard indoor evaporation without drying out too quickly or requiring constant extra moisture or extra steps.

Tips for maintaining normal humidity

• Group plants together.
  Plants naturally release water vapor through tiny pores in their leaves. When you group plants together, they share this evaporating moisture and create a humid mini-climate.

• Set up a pebble tray.
  Fill a shallow tray with pebbles, gravel, or perlite and pour in water until it reaches halfway up. Place your pot next to or on top of the stones. As the water evaporates, it can help raise humidity right around the foliage by a few percentage points.
  
  Important: Make sure the bottom of the pot stays above the water level so the roots don't sit in water and rot.
  

• Use a cool-mist room humidifier.
  Running a modest room humidifier on a timer can help keep a room around 40%-50% relative humidity.

Low humidity (10% - 40%)

Low humidity is standard in arid climates, air-conditioned rooms, and homes heated during winter. Dry air causes water to evaporate rapidly from soil and foliage.

Plants adapted to these conditions have often evolved thick leaves, waxy or hairy coatings, or fleshy stems to store water. Because they are designed to conserve moisture, high humidity can actually cause problems for them.

Tips for maintaining low humidity

• Lower indoor humidity.
  If an area is too humid for your plant’s liking, run a dehumidifier or set up a fan to increase air circulation.

• Avoid humid rooms.
  Plants that prefer low humidity are best placed in rooms with stable, low humidity. Avoid bathrooms, for example.

• Give them breathing room.
  Unlike tropical plants that love being grouped together, space low-humidity plants out so air can move freely around them.