A poinsettia needs at least 6 hours of bright, indirect light daily to thrive indoors, with complete darkness for 14 hours each night during fall reblooming.
For the full breakdown, see our best Grow Light For Poinsettia guide.
Getting the light right is the single most important factor between a poinsettia that lasts through the holidays and one that drops leaves within a week. The plant evolved under the filtered canopy of Mexican forests, so its light needs are specific: enough brightness for color and growth, but never direct sun that scorches the bracts. Here is what that looks like in a typical home and how to adjust for reblooming.
What Kind of Light Does a Poinsettia Need Indoors?
Bright, indirect light is the gold standard. Place the plant near a south-, east-, or west-facing window where sunlight passes through a sheer curtain or is diffused by a nearby tree outside. At least 6 hours of this filtered light per day keeps the leaves green and the bracts colorful. Direct, unfiltered sun—especially through a south-facing window in winter—will scorch the leaf edges and fade the red bracts to a pale pink.
Too little light is the faster killer. If the plant sits more than a few feet from a bright window or in a dim corner, it will drop lower leaves, stretch toward the light source, and look leggy within two weeks.
How Much Light for Reblooming a Poinsettia Next Year?
Poinsettias are short-day plants, meaning they set flower buds only when nights are long and uninterrupted. Starting around early October, the plant needs 14 hours of complete darkness every night for 8 to 10 weeks. From about 5:00 p.m. to 8:00 a.m., it must be in a closet, under a box, or in a dark room with no ambient light—not even a streetlamp through the window or the glow of a TV screen.
During those dark hours, the temperature should stay between 60 and 70°F. Any interruption—turning on a room light for even a few minutes—can delay or ruin the bud set. During the day, the plant still needs its normal bright, indirect light; the dark period is a nighttime addition, not a replacement. After 8 to 10 weeks of this cycle, the bracts will begin showing color, and you can return the plant to normal indoor light.
What Light Levels Are Too Low or Too High?
Normal indoor light levels of 50 to 100 foot-candles—typical of a living room with lamps and a shaded window—will keep the plant alive for a week or two but will not sustain long-term health or reblooming. For good color development, the plant needs bright sunlight (filtered). The sweet spot is a window that receives morning or afternoon sun but is shaded from harsh midday rays.
Signs of too much light include bleached or brown leaf edges and faded bract color. Signs of too little light include yellowing lower leaves, elongated stems, and green bracts that never turn red. If you see either, move the plant a few feet away from the window or closer to it, adjusting gradually over several days.
Where Should I Put My Poinsettia in the House?
Place the plant at a bright window where it avoids direct sun. East-facing windows are ideal—they give gentle morning light. South- or west-facing windows work if you use a sheer curtain. Keep the plant away from heat vents, radiators, fireplaces, and drafty doors; the combination of dry heat and low humidity stresses the plant faster than any light mistake.
Rotate the pot a quarter-turn every few days so all sides receive even light, preventing the plant from leaning toward the window. Avoid placing it near cold drafts (a window crack in winter) or hot air currents (a register below the window). Room temperatures between 65 and 75°F during the day and slightly cooler at night are ideal.
| Light Condition | Daily Needs | Best For |
|---|---|---|
| Bright indirect light | 6+ hours | Long-term indoor health |
| Direct unfiltered sun | Avoid entirely | Causes leaf scorch and faded bracts |
| Complete darkness (reblooming) | 14 hours nightly, 8–10 weeks starting October | Triggers flower bud formation |
| Low indoor light (50–100 foot-candles) | Tolerated short-term | Temporary holding, not long-term health |
References & Sources
- Colorado State University Extension. “Selecting and Planting Poinsettias.” Details on light requirements and care for indoor poinsettias.
- University of Minnesota Extension. “Poinsettia Care.” Guidance on light levels, reblooming cycles, and common care mistakes.
- University of New Hampshire Extension. “Poinsettias: Care and Reflowering Fact Sheet.” Specific instructions for dark-period timing and temperature during reblooming.
FAQs
Can I leave my poinsettia in a window that gets afternoon sun?
Only if you filter the light with a sheer curtain or blinds. Afternoon sun through glass is intense enough to burn the leaves and fade the colorful bracts within hours. Morning or early afternoon sun is much gentler.
How do I know if my poinsettia is getting enough light?
Healthy poinsettias have deep green leaves all the way down the stem, bright bract color, and compact growth. If lower leaves drop, stems stretch toward the window, or bracts stay green, the plant needs more light. Move it closer to a bright window gradually over a few days.
Will artificial room light disrupt the dark period for reblooming?
Yes. Even a few minutes of ordinary room light during the 14-hour dark period can delay or prevent bud formation. The plant must be in complete darkness—a closet, covered with a lightproof box, or in a room with blackout curtains—every night from October through early December.