Watering  Houseplants

Humidity and Plants

Humidity is a measure of the amount of water that air will hold. At 100 percent humidity the air cannot hold any more water. Humidity is measured relative to temperature and is called relative humidity (RH). The measurement is taken this way because humidity and temperature are directly related: the warmer the air, the more water it can hold.

Humidity in the Home

During heating cycles your furnace is taking dry outside air and warming it. If no water is added to this outside air, then it will still be dry. You can increase the by adding water to the air. Warm, moist air is always being lost from the house, and cold dry air is always being brought in, so a low humidity condition is normal for your house when heating is in full swing.

Humidity and Plants

Humidity is important to plants because it helps stop moisture loss from the plant. The leaves of plants have tiny pores. Carbon dioxide enters the plants through these pores, and oxygen and water leave the plant through these pores.

A plant’s natural physical humidity level is near 100%. When placed in a dry environment it will lose moisture because water always moves from high to low humidity. When that difference in humidity is large, a plant loses moisture quickly.

Most houseplants prefer a humidity of about 60%. Cacti, succulents and plants native to desert environments tolerate much lower humidity (30-35%), but prefer not to drop below 20%. Many house plants that are native to tropical rain forests require as much as 90% humidity conditions. Plants that require a very high humidity are best grown in terrariums or closed containers where humidity can be prevented from escaping the environment.

On the opposite end of the spectrum, excess humidity can lead to mildew on plant leaves. This condition rarely occurs but may be evident during major season changes.

Signs of Dry Plants

Plants that are placed in an environment that is too dry suffer damage to younger leaves and to leaf tips. New leaves and leaf tips are the area of the plant with the most actively growing cells, and these cells are the most susceptible damage under these conditions. Mature leaves may be shed as a result of lack of humidity. Plants enduring humidity stress frequently shed flower buds, or the flowers may die soon after opening.

Increasing Humidity

Humidifiers – Add a humidifier to you furnace and utilize a portable humidifier.

Select a Humid Location -  Bathrooms and kitchens that are exposed to plenty of natural light, often have a higher humidity and may be more suitable for house plants requiring extra humidity.

Pot inside a pot – By placing small pots inside a larger pots, you will allow space around the small pot to build in a natural sponge. Fill that little space around it with peat moss and ensure it is always moist. As water evaporates from that wall of peat moss, the humidity it creates will be absorbed by the plant.

Small pea stone In Tray - Fill a large a saucer or tray with small pea stone gravel. Cover your layer of stones with water. Place your potted plant on top of the stone. As the water evaporates keep it replenished. This will provide the plant with

Plave plants in Groups - Moisture loss from one plant can benefit the plant next to it.

Misting - This may be the least effective but the most used method. Misting plants will result in a surface coating of water, which will reduce the rate of transpiration from the leaves. The effects are short lived though because soon after misting the water will evaporate and the benefit is lost. Constant misting can lead to fungal growth and tissue rotting. Plants with hairy leaves cannot be misted, for leaf spotting will likely occur as a result.

Watering

Water houseplants thoroughly so soil is saturated. Discard water that accumulates in the overflow tray as it will accumulate an excess of water soluble salts.

With the exception of ferns, coleus and a few others that require frequent watering, it is best to let the plants become a bit dry before watering again. This slows plant growth during winter months, reduces plants' needs and compensates for lower humidity.

Watering Tips

One of the best ways to accurately determine a plant's need for water is to poke your finger in the soil to the root depth. Notice how the soil feels. If it feels dry, it is probably time to water. If it still feels moist, check again in a day or two.

Apply water until the soil becomes saturated and the excess drains out of the drainage holes into the sink or saucer. Let the pot drain for 15 minutes or so, then discard any excess remaining in the pot's reservoir or saucer. Don't use the surface of the soil as an indicator of a plant's water needs. During the winter, the upper surface of the soil dries out quickly as a result of the furnace running.

Houseplants and proper care