Houseplant temperature guide
Like all living things, houseplants have specific temperature requirements. In order for them to survive and thrive, these must be met. Most plants prefer a temperature of no less than 60° F, though many can tolerate as low as 40° F.
Along with this, while the improper temperature can certainly be an issue, fluctuations in temperature are the true killer. Learn the ideal temperatures for your green friends so they can be healthier and happier.
Why Does Temperature Matter?
Like people and animals, plants require warmth in order to thrive and survive. If you’re cold, then it’s a safe bet that some of your plants are feeling the chill, too!
While many plants are remarkably hardy in lower temperatures, they still require a certain minimum of warmth in order to grow and be healthy. Most indoor varieties require no less than 40° F, and ideally at least 60° F. Alternatively, excessive heat can also be detrimental to plants, especially those that are extra heat-sensitive. These plants are sometimes called ‘heat tender’:
As a matter of fact, temperature fluctuation is the true plant killer. While many species can handle consistently cool temperatures, any rapid and significant changes can prove seriously harmful. It can cause plants to go into shock, and, depending on the severity of the damage, it can take a long time for them to recover. In order to preserve your plants, the temperature should never be altered more than 5-10° F.
What Temperature Do Plants Require?
Most prefer a temperature range of 60-70° F at night and 75-80° F during the day, though many can handle as low as 40° F. The specific temperature requirements of each plant will also depend on its type and native habitat.
As you can imagine, cacti, such as Bunny Ears or the Easter Cactus, prefer exceptionally warm temperatures. As desert plants, they should never be exposed to the cold, preferring no less than 50-60° F and ideally 70-80° F.
While some hardy succulents can tolerate temperatures as low as 40° F, most require at least 60° F. The best temperature for succulents, such as Jade Plants, String of Pearls, Bear Paws, and Lithops, is 70-80° F.
It can be very tricky to get flowers to bloom indoors and to do so, they will need to be warm enough. In order to sustain their blooms, flowers should be kept at 70-80° F during the day and 65-70° F at night. Remember: it must be warm and sunny in order for your plants to flower.
Tender perennials are plants that are extremely cold-sensitive. If exposed to low temperatures, they will quickly die off. For these types of plants, which include the beloved Hibiscus, Impatiens, and Coleus, the temperature should never dip below 60-65° F.
Subtropical and Tropical (Half-Hardy)
Many subtropical and tropical species are known as half-hardy, which means that, while they are more resistant to cold than tender perennials, they are still quite sensitive to lower temperatures. This includes popular choices like the Amazon Elephant’s Ear, the Bird of Paradise, Ficus plants, Peace Lilies, and Orchids. Typically, subtropical and tropical plants require temperatures of no less than 40-50° F, and they thrive in temperatures of 70-80° F.
Hardy plants can grow indoors or out and seem to be made for survival. In the cold season, they will lose their leaves and flowers but continue to live underground. They can handle below-freezing temperatures. Examples of super-cold-resilient types are Phlox, Roses, Peonies, and Lily of the Valley. Indoors, they prefer temperatures of 60-70° F but can handle much colder.
Warning Signs, Reasons and Prevention
Signs Your Plants May Be Too Cold
- Curling leaves. A sign of a chilly plant is when its leaves begin to curl under.
- The leaves brown and fall off. If your plant is too cold, it may begin to die, and its leaves will brown and fall off.
- The leaves turn yellow. Yellow leaves are a sign of many health issues. Cold temperatures are the primary culprit.
- Stunted growth. Cold plants will simply not thrive, and they will grow more slowly.
- No flowers. Flowering plants require warmth and sunlight to sustain blossoms, and they won’t flower when it’s too cold.
- Black spots. When exposed to the cold, plants can develop black spots, similar to frostbite. This often occurs when they are too near a window in cold weather.
What Causes Excessive Cold
So, what can cause plants to become excessively cold? Drafts, for one. These can cause deadly fluctuations beyond 5-10° F. Avoid drafts by keeping your green buddies away from doors and windows in cold weather. In warmer months, cooling vents can also keep your plants excessively cool.
How to Fix It
If you like your house cool, you can opt to keep your cold-sensitive green friends under plant lamps, which will provide not only light but warmth as well. If your home isn’t warm enough, then any plants that seem cold should be moved away from doors, windows, or vents to a location that is more ideal.
Signs Your Plants Are Too Hot
- The leaves wilt. When it’s too hot, the leaves will often go limp and wilt.
- The leaves dry out. Excessively hot plants will dry out faster.
- The leaves turn yellow. One of the causes of yellow leaves is excessive heat, so this is one thing to consider!
- Bolting. Bolting is something that annuals will undergo if it becomes too warm. This involves losing their flowers and fruit rapidly, before the death of the plant itself.
- The leaves suddenly fall off. If the leaves fall off all at once, excessive heat may be the reason. This is also a sign of excessive temperature fluctuation in general.
- The leaves become sunburned. When exposed to extreme heat or sun, many plants will develop what’s called ‘sun scalding,’ also known as a plant sunburn. Afflicted leaves often find it very hard to recover.
What Causes Excessive Heat
If you think your plant is too hot, it could be due to direct sunlight. Most species prefer indirect sunlight. A heating vent may also be responsible. Also, avoid keeping heat-sensitive species in bathrooms where people shower (some species love this; others do not).
How to Fix It
Move too-hot plants out of the direct sun to a spot with more indirect light. Also, avoid heating vents, heaters, stovetops, ovens, and other heat sources.
As you can see, temperature plays a huge role when it comes to houseplant health and proper plant care. The incorrect temperature, or worse, temperature fluctuations, can prove harmful and even deadly. On the other hand, the ideal temperature will enable your green friends to flourish. All that this takes is a bit of know-how!