Poinsettia

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Thrives in a bright window that catches some direct sun, and gets by farther back out of the sun’s reach. Sun is what feeds the summer growth that becomes next winter’s bushy plant.

In December, low winter sun at an eastern window lights the red bracts from the side for a morning hour or two, and the plant takes every bit. Grown outdoors, NC State gives it 4-5 hours of direct light daily, a fair target for an indoor sill as well.

Its real quirk is about the dark. It’s a short-day plant: the bracts color up only after weeks of long, unbroken nights, at least 12 hours of darkness for 8-12 weeks (University of Illinois Extension). Any light at night after October 1 can delay or stop the show (UF/IFAS).

To bring the red back next year, give it full days at the window and nights in a closet or under a box from early October; UF/IFAS notes color comes on fastest at 14-14.5 hours of dark. Skip the routine and it stays a leafy green shrub, a fine plant in its own right. Sun by day, true dark by night: that’s the whole calendar it keeps.

About every 5-7 days in summer and 7-10 in winter, with the surface of the soil drying between. Kept wet, it tends to answer with yellowing, falling leaves.

Most come home wrapped in a decorative foil sleeve, which can hold water around the roots. Slip it off, or poke holes in the bottom, so the roots aren’t left sitting in standing water (University of Minnesota Extension).

Warmth is the other thing to manage. The University of Wisconsin Extension suggests 60-68°F and warns that rooms over 75 speed up its aging, so a cooler room slows its aging. A chill or a hot, dry draft is often what sets the bracts and leaves dropping early, so give it a spot clear of heat ducts and drafty doors.

Gone for a while? A week is fine if it’s soaked the day you leave; much longer and it wilts and drops leaves.

A rounded bush of deep green leaves crowned with color, 1-2 feet tall as sold, rarely 3. Pinch the stem tips in summer: each pinch means more branches, and more branches mean more red come winter.

In the dry tropical forests of Mexico and Guatemala, the same species grows into a shrub or small tree up to 10 feet high and 8 wide (NC State). The many-stemmed pot you bring home owes its dense branching to a phytoplasma that growers pass on by grafting (Penn State), while breeding since the mid-1950s brought larger, longer-lasting bracts (University of Illinois Extension).

Once its tiny flowers shed pollen, it drops its bracts and many leaves (University of Illinois Extension), so a spring poinsettia can look bare. That’s the time to cut it back and let summer growth rebuild the mound; stem cuttings taken in early summer root into new plants (NC State).

Its bracts open flat, like a crown, so the show is best seen from above: set it low, at the center of a holiday table or on a hearth.

A pet that chews it may get a sore mouth or an upset stomach, sometimes with vomiting. For kids, Poison Control calls it nonpoisonous, though the milky sap can still redden skin.

Good news: its scary reputation is bigger than the plant. The ASPCA calls it "generally over-rated in toxicity."

The sap carries diterpenoid euphorbol esters and saponin-like detergents (Pet Poison Helpline). A pet that chews a leaf may drool, and the signs usually clear on their own.

The scare began more than a century ago, with a story of a child found beside a wild poinsettia. Researchers later found no poisonous dose, even at about 1.25 pounds, some 500-600 leaves (Poison Control). The leaves reportedly taste awful, so most chewers quit after one bite (UC Agriculture and Natural Resources).

The sap can cause a rash, and in pets, rarely a mild pink eye (Pet Poison Helpline). Some people with latex allergies have reacted after touching the leaves (University of Illinois Extension), so gloves help when you prune.

If symptoms don’t settle or anything worries you, Poison Control can help with a child, and your vet or the ASPCA can help with a pet (a fee may apply). A mantel or high table keeps it clear of toddlers and curious pets alike, with the color still on show.

1. ASPCA: mild for dogs.
2. Merck Veterinary Manual: mild for dogs (rates the whole genus).
3. Pet Poison Helpline: mild for dogs.
4. ASPCA: mild for cats.
5. Merck Veterinary Manual: mild for cats (rates the whole genus).
6. Pet Poison Helpline: mild for cats.
7. : mild for kids.

Cats and dogs: Most of the leading sources agree.

Kids: Poison Control: children who eat it can get mouth irritation and stomach upset; not dangerous.

Happiest at 65-70°F, and it shouldn’t sit below 60°F. Keep it away from cold glass in winter. Humidity can drop to 30% without trouble.

Temperature

65-70°F

Whiteflies are the likeliest guests, tucked under the leaves, with pupal skins on older ones. Spider mites and aphids also sit on the undersides. Mealybugs hide on stems and in leaf axils, scale on stems and leaves.

• Whiteflies
• Spider mites
• Aphids
• Mealybugs
• Scale

Whiteflies and mealybugs are the usual pests; spider mites and scale turn up too, and soggy soil rots the roots and stems.

Whiteflies are tiny, powdery white insects that rise in a cloud when you brush the plant, leaving yellowing, sticky leaves. Wash the plant well, then spray the undersides of the leaves with insecticidal soap.

Mealybugs look like tufts of white cotton where leaves meet the stem; scale looks like small brown bumps. Wipe them off with a cotton swab dipped in rubbing alcohol, then check again next week. Spider mites leave fine speckling and webbing; insecticidal soap handles them.

Rot shows as stems going soft and dark at the soil line, usually in a pot left standing in water. Empty the foil and saucer after every soak.

Turn the pot monthly and feed half-strength every 3-4 weeks from spring through summer. Pinch tips 3 times a year until mid-August. Prune in spring and repot in early summer, then give 6-8 weeks of long dark nights.

• Feed8× a year
• Prune1× a year
• Pinch3× a year
• Repot1× a year
• Clean leaves2× a year
• Rotate12× a year
• Rebloom darkness1× a year

It comes in a potting mix that drains fast. Keep it in a pot with a drainage hole, out of the foil or with holes poked through it.

Repot in early summer, if you keep it past the holidays, into a pot 2 to 4 inches wider, with a rich potting mix.

Food is optional while it’s in color. If you keep it past the holidays, an all-purpose houseplant fertilizer in spring and summer keeps it growing.

Deep green leaves form a rounded bush, topped with fire-red leaves as the standout. Every leaf is matte and smooth, with no gloss, and the foliage is dense enough to cover the soil.