Temperature Guide for Houseplants
The world of houseplants is vast and diverse. On one windowsill, you can find inhabitants of hot deserts and cool mountain meadows. How to choose the right temperature for each of them?
When choosing a new houseplant for your home, you need to find out: is it heat-loving or does it prefer coolness?
Plants are classified into three groups based on temperature preferences:
- Plants preferring cool temperatures
- Heat-loving plants.
- Temperature-tolerant plants
Plants from subtropical regions and moderate climates thrive in cool environments. Azaleas, camellias, bellflowers, araucarias, and cyclamens dislike excessive heat. 55 – 64°F (13 – 18°C).
Tropical plants prefer warmth and are kept in warmer environments. Most houseplants are tropicals and prefer temperatures between (65-75°F/18 – 24° C) during the day and about 10 degrees cooler at night. Among heat-loving plants are some easy-to-care-for species not too demanding on room temperature, such as dracaenas, monsteras, ficuses, and aloes. They can thrive both in warm and fairly cool environments. However, lowering the temperature to (59°F/15° C) degrees is highly undesirable for aglaonemas, caladiums, and ktenanthes.
Some plants, such as spider plants or sansevierias, thrive equally well in warm and cold rooms.
Air Temperature Control
For constant monitoring of room temperature, a regular thermometer is used, but it's also important to note that the temperature near the window is 2-3 degrees lower than in the depths of the room.
Soil Temperature in the Pot
The soil temperature in the pot is usually 1-2 degrees lower than the surrounding air. In winter, on a cold windowsill, this difference is even greater. Therefore, for some plants (those that like to keep their feet warm), such as gardenias, anthuriums, and ficuses, it's necessary to provide a foam stand on the windowsill or use special pots.
In summer, a dark ceramic pot on a south-facing window can heat up so much in the sun that the soil will be much warmer than even the hot summer air. For many plants, including heat-loving ones, this can be dangerous.
Temperature Fluctuations
Most indoor flowers are very sensitive to sudden temperature changes. This applies not only to air temperature but also to soil temperature and water temperature for watering.
Cold drafts from the window can harm ficus, alocasia, vriesea, gerbera, maranta, and calathea. For example, ventilating the room on a frosty winter day can cause heavy leaf shedding in a ficus Benjamin.
Some plants are available for purchase in winter, such as poinsettias, kumquats, for example. When buying them in the store, it's important to remember that even brief exposure to cold during transportation to your home can lead to complete leaf loss.
Water Temperature
Watering with cold water is not recommended for any plants; it's better to use room temperature water or slightly warmer. An exception is plants in deep dormancy in a cool room; warm watering can lead to premature awakening.
There is a close relationship between plant warmth and moisture requirements. One general rule to remember: the warmer the room, the more water the plant needs. And vice versa: the cooler, the less water it needs.
Temperature for Seed Germination and Cuttings
The heat requirements for houseplants vary at different stages of growth and development. For example, seed germination sometimes requires high temperatures (up to (86°F/30° C) degrees), while emerged seedlings are kept at a lower temperature. Cuttings of almost all plants root poorly in cold rooms. Recently repotted houseplants also need higher temperatures.
Temperature during Dormancy
During dormancy, plants require lower temperatures than during the growing season.
Temperature and Plant Diseases
Temperature fluctuations can trigger certain plant diseases. Many fungi causing root rot, for example, spread especially quickly at low temperatures because the soil dries very slowly after watering. Therefore, if the average temperature is below normal, the risk of root rot increases.
Considering the temperature requirements when choosing a houseplant, it's not difficult to provide it with comfortable growing conditions.