The growth of indoor plants is significantly influenced by temperature, it’s the second most critical factor after light.
Most popular houseplants evolved to live in tropical and subtropical areas. Generally, plants can tolerate and grow well between 58 degrees Fahrenheit (14 degrees Celsius) and 90 degrees Fahrenheit (30 degrees Celsius). Of course, there is quite a bit of variation among categories of those houseplants.
A queen agave, for instance, prefers cooler temperatures of around 50 degrees at night and only 65 degrees during the day. A goldfish plant prefers high temperatures, of 70 degrees at night and 90 degrees during the day.
Temperature and plant growth
Plant growth is a balance of photosynthesis and respiration. Photosynthesis turns water and nutrients into sugars and starches. Respiration breaks down those sugars to maintain tissue and grow new leaves, stems, branches, or blossoms.
Temperature determines the level of respiration. Low temperature means slower respiration, and high temperature means higher respiration.
If a plant isn’t getting enough light to balance respiration, the plant will grow slowly, focusing only on maintaining existing plant tissue. If the light is so low that sugars produced are insufficient for maintenance, the plant will extract nutrients from older leaves to sustain new leaves. Eventually, without enough light to keep in balance, the plant will die.
Striking a balance
To maintain the balance of respiration and photosynthesis and maintain or promote better growth of a plant there are two levers to do so. Either a plant owner must increase light to promote more photosynthesis and sugar production, or they must lower the plant’s temperature (and thus its respiration rate), particularly at night when no sugars are being produced.
It’s important to monitor a plant’s temperature, particularly if the plant isn’t doing well. That means being mindful of temperature fluctuations that may occur throughout the day and across seasons.
During summer, turning off the air conditioning at night or raising the thermostat settings on weekends can result in higher night temperatures, increasing respiration and stressing plants.
Conversely, turning off heating or lowering the temperature can allow temperatures to dip to unsafe levels, especially near drafty windows.
To achieve optimal growth, it’s ideal to maintain a temperature range of 70 degrees Fahrenheit to 80 degrees Fahrenheit during the day and 65 degrees Fahrenheit to 70 degrees Fahrenheit during the day. This will keep the vast majority of the most popular houseplants thriving.
The Sprout Houseplant Tender makes this a lot easier. It monitors temperature every minute of every day, and sends alerts if a plant needs more light or might fare better in another window.