Gadenin日本語Get the appThe journey home does the damage
A poinsettia is a tropical shrub and it is intolerant of cold in a way that surprises people who buy it as a winter plant. Ten minutes in a cold car park, or a boot at freezing point on the drive home, is enough to cause damage that shows up a week later as wholesale leaf drop. The plant looks perfect in the shop and perfect when you unwrap it, and then falls apart.
The rule is simple: never let it sit below 50F (10C), even briefly. Ask for it to be sleeved properly before you leave the shop, carry it inside your coat if it is freezing, put it in the car cabin rather than the boot, and do not leave it in the car while you do the rest of your shopping. Once it is home, unwrap it straight away rather than leaving it bagged in a cold hallway.
Damage from cold appears three to ten days after the event, not immediately. If leaves start dropping in the second week and you have watered correctly, look back at how the plant traveled.
Temperature: warm, but not hot
The comfortable range is 60 to 70F (16 to 21C) by day and no lower than 55F (13C) at night. Within that band the bracts hold their color for two or three months. Above it the display goes over quickly, and below it the plant sulks and starts shedding.
Cooler is better than warmer for making the color last, as long as you stay above 55F (13C). A plant in a hall at 60F (16C) will still look good long after an identical plant in a living room at 75F (24C) has dropped its bracts.
| Temperature | Effect on the plant | What to do |
|---|---|---|
| Below 50F (10C) | Leaf drop within days, often fatal | Move it immediately, do not water while cold |
| 50 to 55F (10 to 13C) | Growth stops, lower leaves yellow | Move somewhere warmer at night |
| 60 to 70F (16 to 21C) | The right range, color lasts longest | Hold it here |
| Above 75F (24C) | Bracts fade and drop early | Move away from the heat source |
| Fluctuating by more than 15F (8C) | Leaf drop even within the safe range | Steady position matters more than the number |
Drafts are the second killer
After cold, the thing that strips a poinsettia fastest is moving air. A plant by a front door that opens onto a winter street, or under a heating vent, or on a windowsill above a radiator with a gap behind the curtain, gets a pulse of temperature change every few minutes. It responds by shedding leaves from the bottom up.
Walk round the room and hold the back of your hand where the plant will go. If you can feel air moving, or the temperature changing as you stand there, choose somewhere else.
- Keep it away from doors that open outside Entrance halls and porches look like the natural place for a display plant and they are the worst position in the house. Every opening of the door hits it with outdoor air.
- Not directly above a radiator Rising hot dry air browns the leaf edges and dries the pot unevenly. If a windowsill is the only bright spot, put a board or a tile under the pot and pull the curtain in front rather than behind the plant.
- Off the glass at night The air against a window pane on a cold night can be 15F (8C) colder than the room. Leaves touching the glass blacken where they touch. Move the plant back into the room at night, or draw the curtain in front of it.
- Away from fruit bowls Ripening fruit gives off ethylene, and poinsettia bracts and leaves drop in response to it. Keep it off the same table as the apples and bananas.
Light through the year
A poinsettia wants as much bright light as you can give it indoors, with direct winter sun being perfectly acceptable. It is not a shade plant, and a dark corner is the reason many end up leggy and pale by early spring. Six hours of good light a day is the target, and in midwinter that usually means right up against a south or west facing window.
| Season | Position | Reason |
|---|---|---|
| Winter, in bract | Bright window, back from the glass at night | Holds color and stops leaf drop |
| Spring, after cutting back | Brightest window you have | New shoots need light or they come thin |
| Summer | Outdoors in dappled shade, or a bright window | Strong growth, but shield from midday sun |
| Autumn, dark treatment | Bright ten hours, then fully dark | Both halves matter equally |
Turn the pot a quarter turn each time you water. A poinsettia leans hard towards the light and an unturned plant ends up one-sided by spring.
Summer outdoors, and what to note
Once nights are reliably above 55F (13C) the plant does far better outside than in, and a summer outdoors is the single biggest thing you can do for the size of next winter's display. Put it in dappled shade or somewhere that gets morning sun only, and move it into full light gradually over a fortnight so the leaves do not scorch.
Bring it back indoors well before nights fall below 55F (13C) in autumn, which normally means moving it in at the same time you start the dark treatment. Check the undersides of the leaves and the rim of the pot for pests before it comes in.
Worth recording: the date you put it outside, the date you brought it in, and the lowest night temperature you were comfortable leaving it out in. Next year those three dates let you make the same decision without guessing, and they anchor the start of the dark treatment as well.