Poinsettia Care: Keep It Alive & Make It Rebloom

The poinsettia (Euphorbia pulcherrima) sells by the million every December and, unfairly, ends up in the bin by January. Treated as a houseplant rather than a disposable decoration, it can live for years — and if you kept last year's plant, this is the one article to read now, because the countdown to turning it red for Christmas starts in the next couple of weeks.

Those red 'flowers' are leaves

The showy red, pink, white, or marbled parts are bracts — modified leaves. The true flowers are the tiny yellow bead-like structures (cyathia) at the centre of each bract cluster. That distinction matters when buying: a plant whose cyathia are still tight and yellow is fresh; one that has shed them is already past its peak. In the wild in Mexico, the poinsettia is a lanky shrub several metres tall that colours up as winter days shorten — a fact that explains almost everything about its care.

Buying and getting it home

Poinsettias are badly damaged by even a few minutes below about 10°C. Avoid plants displayed by shop doorways or outdoors in winter, ask for the plant to be wrapped, and don't leave it in a cold car. A chilled poinsettia often looks fine at the till and drops all its leaves a week later.

Light, warmth, and position

Give it a bright spot with indirect light — near a window but out of strong midday sun — and steady warmth of 15–21°C. What it cannot stand is fluctuation: cold draughts from doors and single-glazed windowsills at night, or hot dry blasts from a radiator directly beneath it. Leaf drop is almost always a position problem before it is a watering problem.

Watering and feeding

Water only when the top couple of centimetres of compost feel dry — typically every 4–7 days in a warm room — and always let the excess drain; a poinsettia left standing in a saucer of water will rot. Wilting dramatically then recovering after a drink is a sign you're cutting it too fine, while yellowing lower leaves plus constantly damp compost means the opposite. While the plant is in colour it needs little feeding; once it's growing again in spring, a balanced liquid feed every 3–4 weeks is plenty.

Warning: Like all Euphorbias, poinsettias bleed a milky latex sap that can irritate skin, eyes, and pets' mouths and stomachs. The old story that a single leaf can kill a child or cat is a myth — serious poisoning is very rare — but keep the plant away from nibbling pets and wash your hands after pruning.

The year in between: spring and summer care

When the bracts finally fade (often March or April), cut the stems back to 10–15 cm, repot into slightly larger, free-draining compost, and grow it on somewhere bright and warm. It can spend summer outdoors in a sheltered, lightly shaded spot once nights stay above about 12°C. Pinch the shoot tips once or twice before August to keep it bushy. Bring it back indoors before the first cool nights of autumn.

The dark treatment: turning it red again

Poinsettias are short-day plants: the bracts only colour when the plant gets long, absolutely uninterrupted nights for weeks on end. Commercial growers do this with blackout screens; at home you do it with a closet and a calendar.

• Start between late September and early October — 8 to 10 weeks before you want full colour.
• Every evening, give the plant 12–14 hours of total darkness: a dark cupboard, an unused room, or a sealed cardboard box over the plant from roughly 5 pm to 7–8 am.
• Every morning, bring it back to a bright spot — it still needs good light (up to about 10 hours) during the day.
• Keep it at 15–21°C, water as normal, and hold off fertiliser during the treatment.
• Be strict: even a brief burst of light in the dark period — a hallway lamp, a car headlight through the window — can delay or cancel colouring.
• Once the bracts are clearly colouring (usually late November), stop the routine and display the plant normally.

Tip: Put a recurring reminder on your phone for the blackout hours. The single most common reason home reblooming fails is a forgotten evening — and one skipped night matters less than a light switched on mid-darkness.

Troubleshooting

• Sudden leaf drop days after purchase — cold shock on the journey home or in the shop; keep it warm and stable and it may regrow.
• Steady lower-leaf yellowing and drop — overwatering; let the compost dry further between drinks.
• Wilting with dry compost — underwatering; water thoroughly and shorten the interval.
• Leaves curling and crisping at the edges — radiator heat or hot dry air; move it and consider grouping plants.
• Kept plant stays stubbornly green in December — the dark treatment started too late or the nights weren't fully dark.

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