Temperature for Houseplants
Most house plants tolerate normal temperature fluctuations. In general, indoor foliage plants grow best between 70° and 80°F during the day and from 60° to 68°F at night. Most flowering indoor plants prefer the same daytime range, but grow best at nighttime temperatures from 55° to 60°F. The lower night temperature induces physiological recovery from moisture loss, intensifies flower color, and prolongs flower life. Excessively low or high temperatures may cause plant failure, stop growth, or cause spindly appearance and foliage damage or drop.
One room in a building may be cooler than another. A minimum/maximum thermometer will pinpoint such differences. These temperature variations should be considered when you are placing plants.
Sudden temperature changes can be harmful to houseplants. If houseplants are put outside for the summer, wait until the night temperatures are above 60°F. They should be returned inside before the night temperature drops below 60°F. Plants can be acclimated to temperature changes, if the change is gradual.
If a plant is positioned near a window, protect it from heat and intense sunlight during the day and from cold, drafty conditions at night. On a cold winter night, a plant near the window could freeze. Some protection can be gained by placing a sheet of cardboard between the plant and the window. Use shades and curtains or move the plant far enough away from the window to avoid temperature and light extremes.
Transporting House Plants
On cold winter days, wrap plants thoroughly before leaving the store. Use newspaper, paper bags, or plastic sleeves. Place your new plant in the front of the car, and turn on the heater. The trunk of most cars is too cold to carry plants safely during winter months. Many foliage plants will be damaged if the ambient temperature drops below 50°F. Some plant show chilling injury quickly, while other plants like dieffenbachia may not show the damage for several weeks.
© Erv Evans, Consumer