Houseplant Basics 101: Temperature & Humidity

If you were providing your houseplants an ideal world, then you would help them to feel at home by adjusting the temperature of their indoor environment to mimic their natural environment. However, this is not really practical and your own comfort will most likely come before your houseplants. And even if you were to choose the comfort of your houseplants over your own, the reality is that your home has warmer and cooler spots that are just waiting to present problems.

Since there are so many species of houseplants, it would follow that there is a wide range of ideal growing temperatures. Lucky for us that houseplants are fairly tolerant and reasonable when it comes to variations from their ideal. As a general rule of thumb, you will want to keep temperatures during the nighttime a few degrees cooler than the temperatures of the daytime.

The cooler nighttime temperature is important because it allows your houseplants to store energy. When the temperature at night is hot, your houseplants have no choice but to burn a portion of the energy that they worked so hard to accumulate during the day. Flowering houseplants especially appreciate a cool rest in the evenings because it prolongs the life of the flowers and the intensity of the colors.

Here is a list of conditions that your houseplants will generally NOT like:

• Extreme changes in temperature
• Cold drafts from windows or exterior doors
• Hot air blasts from fireplaces, heat registers or exterior doors
• Close proximity to hot or cold window panes
• Night temperatures that dip below 57˚F (14˚C)
• Daytime temperatures in the upper 68˚ to 86˚F (20˚ to 30˚C)

Relative humidity is simply a measure of the amount of water that the air will hold in a given temperature. The reason that it becomes an important factor in the health of your houseplant is that it affects the amount of moisture that your houseplant may lose.

The ideal relative humidity for the majority of houseplants is about 60%. However, during the winter when our homes are much drier, a more realistic percentage to aim for is 25%. Do not try to raise the relative humidity to 60% during the winter as your windows will have more condensation that you would probably want or enjoy. Although your plants may appreciate your efforts, remember that you can grow a beautiful houseplant in a dry home or office. Keep in mind that there are both deserts and rainforests in nature and plants will thrive in both types of environments.

Here is a list of ways to maintain an ideal humidity level for your houseplants:

• Use a humidifier
• Group plants closely together so they can benefit from each other’s transpiration
• Keep plants away from heat sources such as registers and fireplaces
• Grow plants that are extra sensitive to humidity in a terrarium if they are small enough

Some of the symptoms that you may see that may indicate that a houseplant is suffering from a lack of water, including relative humidity are brown leaf edges, abnormally small leaves, misshapen plant growth and drooping or wilting. It is important to remember that in most cases, the real problem will be a lack of soil moisture and not a low relative humidity.

How do you address the problems of temperature and humidity in your houseplants? Leave me a comment and share.

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