The most common reason poinsettias drop their leaves is due to sudden exposure to temperatures cooler then 55°F. Poinsettia’s are native to hot and dry forests in Mexico and do not tolerate cold temperatures. Even brief exposure to temperatures cooler then 55°F can cause all of the poinsettia’s leaves to drop.
However it should be noted that poinsettias drop their leaves due to stress if the conditions of they are cultivated in are contrary to the preferred conditions of their natural habitat, so to prevent poinsettia dropping their leaves it is important to replicate some of the elements of their natural environment.
It is worth noting that the poinsettia’s red leaves, that are displayed at Christmas time are actually bracts (which is a specialized red colored leaf, rather then a flower) that fall off as part of a natural cycle after Christmas.
Here is a table summarizing the most common reasons for poinsettias losing their leaves:
|Common Reasons for Poinsettia’s Losing Their Leaves:||Explanation for Leaf Drop:|
|Cold Temperatures:||Temperatures cooler then 55°F (13°C) cause the leaves to drop, even if the exposure was brief.|
|Temperature Fluctuations:||Poinsettias prefer a stable temperature range of 65°F to 70°F (18°C to 21°C) during the day and around 60°F and 65°F (15°C to 18°C). Any significant, sudden fluctuation in temperature (whether hot or cold) can cause leaves to drop. This is often due to indoor heating in the Winter.|
|Excessive Air Flow/Low Humidity:||Poinsettia leaves should be misted as they prefer high humidity. Air conditioning, indoor heating and draughts can all reduce humidity causing the leaves to lose moisture and drop off.|
|Overwatering (leaves wilting, then falling off):||Watering the poinsettia too often deprives the roots of oxygen and interferes with the roots ability to draw up moisture, causing the leaves to wilt and drop off.|
|Too Much Shade:||Poinsettias require bright indirect light and can drop their leaves if they are in too much shade.|
|The Red Leaves (bracts) Naturally Drop After Christmas:||The red leaves that are associated with Christmas time often fall off after Christmas, as they are displayed to attract pollinators in Winter in their native environment and drop off due to the natural cycle of the poinsettia.|
Keep reading to learn why your poinsettia leaves are dropping off and how to implement the solutions to save the poinsettia…
Temperatures Cooler then 55°F (13°C) Causes the Poinsettia’s leaves to Drop
The most common reason for poinsettias dropping their leaves prematurely is because it has been exposed to temperatures lower then 55°F (13°C). Poinsettias are native to hot and dry environments in Mexico and do not tolerate even brief exposure to the cold without dropping their leaves.
If the poinsettia has gone from beautifully presented store bought plant with abundant red leaves (bracts) and started dropping its leaves shortly after purchase, then it is most likely that the poinsettia has been exposed to unfavorably cold temperatures whilst in transit form the store to your house.
Poinsettias are of course most often bought in the Winter in the run up to Christmas when temperatures are particularly cold.
Poinsettias are sensitive enough that even a short journey in temperatures lower then 55°F from the shop to the car can cause sufficient cold stress for the leaves to start dropping in the days after placing it in your house.
It could have even been stored badly at the garden center or store in which you bout the poinsettia, if the shop has stored the poinsettia outside temporarily or in a cool area with an open door.
Once the poinsettia has suffered the cold shock there is not much you can do to revive it, other then follow the best practices of cultivation by misting any remaining leaves every day (poinsettia’s prefer some humidity), water the potting soil thoroughly once the surface of the soil has begun to dry and locate the poinsettia in an area of bright indirect light with stable room temperatures.
However, I must emphasize if the poinsettia has lost its red leaves before Christmas, it cannot regrow new leaves until the following year.
Temperature Fluctuations Result in Poinsettias Losing Leaves
Poinsettias prefer stable daytime temperatures of between 65°F to 70°F (18°C to 21°C) and a slightly cooler night time temperature of between 60°F and 65°F (15°C to 18°C). to maintain their leaves.
Poinsettias have adapted to growing in environments with these specific temperature ranges and they do not tolerate any significant deviation of either hotter or cooler temperatures, or they lose their leaves due to stress.
This can be particularly problematic during Winter as indoor heating in the evening raises the temperature at night which is contrary to the poinsettias preferred conditions of slightly cooler temperatures at night, and can result in the poinsettia dropping leaves.
To try to maintain any leaves that remain, locate the poinsettia away from any direct sources of heat such as forced air or radiators and away from cool draughty window sills.
If the poinsettia is placed on a window sill and the curtains are drawn then this can create a micro climate that is too cold for the poinsettia to tolerate and the glass of the window pane can be significantly colder then the rest of the room.
Therefore if any of the poinsettia’s leaves are in contact with the window they can suffer cold damage and drop off.
An area in a living room that has bright indirect light, away from draughts and away from any direct sources of heat creates the optimal environment for the poinsettia to retain any of its remaining leaves.
Excessive Air Flow and Low Humidity Cause Leaves to Drop
Poinsettia have adapted to grow in a relatively stable environment and actually prefer relatively high humidity.
If the humidity is too low this can sap too much moisture from the poinsettias leaves and cause them to drop off as a way of conserving moisture.
The air indoors is often significantly dryer in Winter then any other time of year due to the increased use of indoor heating which dries out the air. Also consider the use of forced air, air conditioning or open windows and doors which can all cause temperature, airflow and humidity to fluctuate unfavorably for the poinsettia.
This makes it all the more important that the poinsettia is located away from any direct sources of heat or draughty areas from frequently open doors or windows and that you counteract any dry air in the house by increasing the humidity.
The most effective way of increasing humidity is with specialized plant humidifier which are available online or you can mist the leaves with a spray bottle every day or so, to slow down the rate of water loss from the leaves and emulate the humid conditions of the poinsettia’s native environment.
Poinsettia Leaves Wilting and Falling Off- Overwatering
The reason for poinsettia leaves wilting and then falling off is because of overwatering. Poinsettia prefer the soil to dry slightly between bouts of watering. If the soil is consistently form watering too often, the leaves begin to wilt as a sign of stress before dropping off due to too much water causing a lack of oxygen in the soil.
Poinsettias are native to Mexico, where they grow in relatively dry forests with relatively high humidity.
The frequency of rainfall and the drainage characteristics of the poinsettia’s soil in their native environment means that the poinsettia have adapted to slightly dry conditions and prefer the surface of the potting soil to dry before watering again.
If the soil is watered too often then the excess water in the soil excludes oxygen from around the roots. This prevents root respiration which interferes with the roots ability to draw up moisture and nutrients from the soil.
If the poinsettia’s roots cannot draw up moisture and nutrients then they the moisture does not reach the poinsettia’s leaves which causes them to wilt. If the poinsettia is consistently overwatered for an extended period then the wilting leaves eventually fall off.
How to Save it…
Whether or not your poinsettia can be saved depends on how long it has been in damp soil as it can develop root rot and the poinsettia can die back if the soil is saturated for too long.
However, sometimes the poinsettia can be saved if you scale back the watering to mimic the moisture conditions of the poinsettia’s natural habitat.
This means waiting for the surface of the soil to feel dry to the touch before watering the poinsettia again.
How long it takes for the soil to dry at the surface (and therefore how often you should water your poinsettia) varies according to different conditions (such as the temperature of the room, the size of the pot etc.) so there is no universal advice for how often you should water your specific poinsettia as it is subject to your specific conditions in your house.
However, as long as the surface of the soil feels dry before you water, then this should achieve the balance of providing the poinsettia with enough moisture to meet its requirements whilst avoiding leaf drop due to overwatering.
Typically this means watering poinsettias around once a week with a generous soak.
Ensure that water trickles from the drainage holes in the base after watering to ensure that the potting soil is evenly moist, so that the roots can access the moisture they require.
If you scale back the watering to replicate the typical, soil moisture conditions of the poinsettia native environment then it can potentially recover.
(Read my article, how to revive a dying poinsettia).
Too Much Shade can Cause Leaves to Drop
Poinsettias thrive in bright areas with lots of natural light. If they are located in a shady room, perhaps with a North facing window without much bright light then the poinsettia can wilt start to lose its leaves.
Poinsettias are native to hot and dry forests in Mexico and grow under the canopy, so that their leaves are protected from harsh direct sunlight, however the light under the canopy is bright which charges the poinsettia with energy for displaying the red leaves (bracts) and flowering.
If the poinsettia is in too much shade it does not have the resources it requires to grow and display its red leaves and flowers, which can result in the leaves dropping off.
Mimic the conditions of the poinsettia’s native environment by placing the poinsettia in a nice bright spot in the house with bright light, yet avoiding any direct sunlight, to achieve the optimal balance of light for the poinsettia to retain its leaves and grow.
The Red Leaves (Bracts) Naturally Drop After Christmas
The red flowers as discussed are not actually flowers but specialized leaves called bracts which are colored red in order to attract pollinators, whereas the flowers are in the center of the bracts and are actually rather small white flowers.
These leaves (bracts) naturally fall off after they have fulfilled their job (to attract pollinators to the flowers), in their native environment and do not regrow until the following year.
Poinsettias require a specific sequence of events in order to produce the red leaves and flowers around Christmas time.
Poinsettia rely on being photoperiodic which means the light conditions indicate to the poinsettia to start to produce the red leaves in time for their key pollinator to find their flowers.
When their are less hours of daylight compared to hours of darkness for a period of 5 weeks or more, this stimulate the poinsettia to start to display red leaves and the flowers emerge.
If there is any unnatural light during the 5 week period that interrupts the period of darkness overnight from turning on a light, then this can prevent the poinsettia form developing new red leaves.
To learn more about how to get your poinsettia to flower again and display its red leaves I recommend you read this university article which explains the sequence of events required to stimulate flowering.
- Poinsettia drop their leaves due to overwatering, low humidity or they are exposed to temperatures cooler then 55°F (13°C). Poinsettias naturally drop their red leaves after Christmas as part of their seasonal cycle.
- Poinsettia leaves wilt and drop off because of overwatering. Poinsettias are native to hot and dry climates and prefer the surface of the soil to dry out between each watering. If the soil is too damp then the poinsettia leaves wilt and drop off.
- To save a poinsettia that is losing leaves, recreate the conditions of the poinsettia’s native environment by increasing the humidity with regular misting, maintaining a stable temperature range of between 65°F to 70°F and wait until the surface of the soil dries out before watering.