Poinsettia in a can

Poinsettia Growing Zones – Information On Poinsettia Cold Tolerance

Poinsettias are familiar plants around the winter holidays. Their bright colors chase winter’s gloom from the dark corners of the home and their ease of care make these plants perfect for interior gardening. Poinsettias are native to Mexico, which means the United States Department of Agriculture poinsettia growing zones are only 9 to 11. But what is the actual cold hardiness of poinsettias? You need to know what temperatures can damage or kill your plant if you are using it as a garden accent.

Is Poinsettia Hurt by Cold?

In their native region, poinsettias can grow up to 10 feet (3 m.) and produce huge bushes with the characteristic flaming leaves. As a houseplant, these lovely plants are usually sold as container specimens and rarely achieve more than a few feet in height.

Once the brilliant leaves fall, you may choose to move the plant outdoors…but be cautious. Poinsettia frost damage can occur at warmer temperatures then you might realize.

Poinsettias grow wild in Mexico and Guatemala, warm regions with mild nights. The blooms are actually colorful bracts, which appear when the inconspicuous flowers arrive, and persist months after the flowers are spent. However, eventually the colorful bracts will fall and you will be left with a little green bush.

You can move the plant outdoors but poinsettia frost damage is a real threat if your area’s temperatures dip below 50 degrees Fahrenheit (10 C.). At this range, the cold hardiness of poinsettias is below its tolerant point and leaves will drop.

If the plant experiences sustained temperatures of 50 F. (10 C.) or below, the entire root system will likely be killed. For this reason, only grow the plant outdoors in summer and make sure it is back inside before any chance of cold appears.

Poinsettia Growing Zones

Check with your local extension office to find the date of the first and last frost in your area. This will give you an idea of when it is safe to bring the plant outdoors. Of course, you should also wait until ambient temperatures are at least 70 F. (21 C.) during the day and are not falling below 50 degrees Fahrenheit (10 C.) at night. This will be within survivable poinsettia growing zones.

Usually, this is from June to July in temperate zones. Warmer zones may be able to move the plant outdoors earlier. If you are going to try to re-bloom the plant, keep it in its pot and pinch new growth during the summer to keep the plant compact and contained.

Fertilize every two weeks during summer with a liquid formula. Provide organic mulch around the root zone if you are in an area where surprise cold nights can occur in summer. When weather reports indicate temperatures will be below poinsettia cold tolerance, move the plant indoors.

Reblooming tips

Once you have gotten the plant indoors before temperatures hit the poinsettia cold tolerance level, you have won half the battle. Place the plant in a dark area from 5:00 p.m. to 8:00 a.m. from October to November (around Thanksgiving).

Poinsettias need 14-16 hours of darkness to promote flowering for at least 10 weeks. Make sure the plant still has some sunlight during the day and continue to water when the soil is dry to the touch. Stop fertilizing once you see the plant begin to produce colorful bracts.

With a little luck and protection from drafts and cold outdoor temperatures, the plant should thrive and may produce an impressive color display anew.

The Dos and Don’ts of Poinsettia Care

Photo: istockphoto.com

During the holidays, nothing rivals the floral festivity of the season’s favorite plant: the always colorful poinsettia (Euphorbia pulcherrima). Whether you prefer the traditional red variety or favor hybridized pastel pinks and yellows, you’ll want to provide the best poinsettia care in order to enjoy the plant’s showstopping blooms as long as possible. Simply abide by these six best practices—and avoid the six biggest mistakes—when tending to this ornamental houseplant.

DO Purchase the Healthiest Plant You Can Find

When shopping for a poinsettia, choose a stocky plant with dense foliage that’s deep green in color, and pass on plants with yellowing or dropped leaves. The colorful flowers, called bracts, should be firm with little or no pollen visible in the center.

DON’T Forget to Protect the Plant in the Car

Some stores sell poinsettias in cellophane cones that will protect the plant from wind damage, but if it’s bitterly cold outside, the bracts and leaves could still suffer. Ask for a larger bag to put over the top of your plant to protect it on the trip to the car and into your home.

DO Position Your Poinsettia in a Well-Lit Location

A southern window is ideal. Poinsettias benefit from plenty of direct daytime light to keep them from getting leggy. If a sunny window isn’t available, choose as bright a spot as possible.

DON’T Let the Leaves Touch a Freezing Windowpane

Poinsettias are tropical plants typically grown in greenhouses, so despite their popularity in winter, they despise the cold. Any leaves that press against an icy window after you position the plant in your home will perish, and the chill could even affect the health of the poinsettia as a whole. Prevent an untimely demise by setting your poinsettia safely on a table in front of a window rather than on a windowsill.

DO Make Sure Your Plant Gets Adequate Darkness

In order for those red or white flowers to last more than a month, poinsettias require more than 12 hours of darkness during their peak bloom period. If you’ve placed the plant in a room that you keep lit all evening, just move it to a darker room, closet, or shadowy corner when the sun sets, then put it back in the window the next morning.

Photo: istockphoto.com

DON’T Put Your Poinsettia in a Drafty Spot

The tender leaves and bracts wilt in windy conditions, so keep your plant away from open windows, forced-air registers, and fans.

DO Water Your Plant

Poinsettias should be watered whenever the soil surface feels dry to the touch. The best way to water the plant is to move it, pot and all, to the sink and soak it thoroughly. Let it drain until no more water runs out—this will take about an hour—and then place it back in its spot.

DON’T Let Your Poinsettia Stand in Water

Sure, soaking your poinsettia’s soil is the best way to quench its thirst, but be sure to pull off the shiny foil wrapper that came tucked around the pot before you water it. Though pretty, this wrapping prevents the water from draining out, leaving the poinsettia’s soil saturated and roots soggy. Waterlogged roots stress the plant and can lead to leaf-dropping—or worse, a short life.

DO Prune Your Poinsettia If You Plan to Reflower It Next Year

Follow the poinsettia care tips outlined so far, and you may find that your houseplant survives from winter into spring—or even longer. If you plan on keeping it around, prune the stems back to six inches when the plant begins to get leggy, and continue to place it in a sunny spot that’s about 65 degrees Fahrenheit. Continue to water just as you did before, and feed your poinsettia regularly every two weeks after they’ve stopped blooming with a standard houseplant fertilizer (view example on Amazon). New shoots will eventually develop at the buds below the cuts. In late spring, when overnight temps outdoors are above 50 degrees, prune new shoots back to four inches and sink your poinsettia—pot and all—into a protected spot in your flower bed and let it stay there until early fall when overnight temps dip back into the 40s. While year-round poinsettia care takes commitment on your part, you’ll be rewarded with an even-larger floral wonder the following holiday season.

DON’T Leave a Large Poinsettia in a Tiny Pot

As a poinsettia grows over the summer, its roots grow as well, and they can get cramped in a small pot. So, when you bring your poinsettia indoors after its spring and summer sojourn in the flower bed, be sure to transfer it into a larger planter. Repotting keeps the plant from becoming root-bound. Choose a new pot about two inches wider and an inch or two deeper than your current pot to give your poinsettia’s roots room to spread out during the coming fall growing season and help stimulate foliage growth and bloom production.

DO Keep Pets Away from Poinsettia

One thing pretty much everyone knows about poinsettia care is the importance of keeping poinsettias out of the reach of furry members of the family. While scare stories link the plants to pet poisoning, the milky sap of the poinsettia actually contains low-toxicity chemicals that can cause vomiting, diarrhea, drooling, and itchiness if a pet eats a large amount. Even though the risk is pretty low, don’t chance it. Keep your plant away from Fluffy or Fido.

DON’T Hesitate to Call Your Vet If Your Animal Eats It (Just in Case)

The pesticides used at garden centers and nurseries could cause reactions if your pet ingests poinsettia leaves, especially if you have a very young animal. If you’re concerned about persistent or severe symptoms, call your vet or the ASPCA Animal Poison Control Center at 888-426-4435. A consultation fee may apply.

Photo: istockphoto.com

When Do you Bring a Poinsettia Inside for the Winter?

Question:

My Mom inherited a poinsettia when her Aunt passed away this summer. It’s huge and in a big pot. Aunt Doris kept it on a screened porch year ’round. My Mom has had it sitting on her deck that is on the southwest side of her home. It’s very lush and green.

She needs to know if and when it needs to be taken inside and any special care instructions for this winter and care tips for it in general. Thanks so much in advance!

Hardiness Zone: 7b

Sharon from Benton, AR

Answer:

Tell your mom to bring her poinsettia in when temperatures start to dip near 55ºF. Once temperatures fall below 50ºF, poinsettias are at risk for cold damage.

Your mom will need to find a sunny location indoors and one that is away from cold drafts and the hot, dry air from fireplaces and heat ducts.

Poinsettias should be watered when the surface of the soil they’re growing in feels slightly dry to the touch. Water them until water begins to seep from the drainage holes in the bottom of the pot, but don’t allow water to stand in the drip tray. Feed poinsettias a 1/2 strength liquid fertilizer once per month from spring until fall.

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Poinsettias are photoperiodic plants (they set their buds and flowers in response to particular day length) and if left to their own devices, most varieties would prefer to bloom around Thanksgiving rather than Christmas.

To get them to bloom in time for Christmas, the plant’s exposure to light needs to be carefully controlled starting in mid-September or early October, at which time plants are kept in total darkness for 13 to 14 hours every day. Although there’s not enough time to force your mom’s poinsettia to bloom in time for this Christmas, she can always shoot for next year if she’s up for the challenge.

In the spring, poinsettias can be returned outdoors after danger of the last frost has passed. She can prune it back at that time, move it to a slightly larger pot (if necessary), and resume fertilizing.

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Starting in mid-September or early October, the plants need 13 to 14 hours of total darkness alternating with 6 to 8 hours of bright light. Nighttime temperatures during this time should be between 60ºF to 70ºF. Stray lights (from streetlamps, cars, houses, etc.), or deviations from this temperature range can disrupt the bud setting process. This routine needs to be kept up for 8 to 10 weeks in order to force the plant to set buds and flower.

Ellen

Poinsettias

Poinsettia is the most popular holiday flowering plant. The plant’s common name comes from Joel Poinsett, the first U.S. ambassador to Mexico, who introduced the plant to the U.S. in 1825.

In its native Guatemala and southern Mexico poinsettias are large shrubs or small trees. The showy “flowers” are actually a combination of bracts and cyathia. The bracts, which are modified leaves, appear to be colorful petals and the cyathia, which are the true flowers, create the yellow center.

In 1919 poinsettia was mistakenly labeled poisonous. The American Medical Association’s Handbook of Poisonous and Injurious Plants states eating poinsettia may cause occasional vomiting. Because poinsettia leaves are reported to be very bitter, most children and animals are discouraged from eating them. Poinsettias, as members of the Euphorbia family, produce a milky sap that may irritate the skin in some people.

For almost one hundred years the Ecke Poinsettia Ranch just north of San Diego has been the center of poinsettia breeding. Almost all the sizes and colors (pink, white, peach, yellow, freckled, or marbled) of poinsettias originated there.

When shopping for poinsettias look for a full robust plant with deep green leaves completely down the stem. Yellow or damaged leaves may indicate poor handling or a disease problem that will limit the life span of the plant. Check the plant from all sides. It should be well balanced with thick, stout stems.

Poinsettias rarely develop their full beauty in the home if bought early so look for mature plants. The bracts should be fully colored without green edges and lie horizontal. Little to no pollen should be seen on the yellow cyathia in the center.

After choosing the perfect plant protect it from the cold during the trip home with paper or plastic. Tropical poinsettias are easily injured by our cold weather this time of year.

In the home, position your poinsettia near a bright sunny window; east, south, or west exposures are the best. Do not let any plant parts touch the cold windowpane because the cold temperature will damage them.

Poinsettias prefer temperatures of 65 – 70°F. Higher temperatures will cause the leaves to yellow and fall, and the bracts to fade early. Temperatures below 50°F. will cause leaf drop. Keep poinsettias out of cold drafts and away from heating sources.

Check the soil surface daily. If the surface is dry, water the plant thoroughly. You’ll know you added enough when water comes out of the drainage holes at the bottom of the pot. If the pot is in a saucer or enclosed in decorative foil, always drain the excess water in the saucer or foil to prevent root rot. Do not allow the soil to dry out or the poinsettia will wilt and loose its leaves.

Poinsettias should not be fertilized while they are blooming.

With proper care and the right environment, the showy bracts of poinsettias should last several months.

After the bracts fade, many people discard the plant because it is difficult to get poinsettias to rebloom. If you’d like the challenge, after the bracts fade in March or April cut the plant back to 8 inches tall. Keep in it in a sunny window, water regularly, and fertilize every two weeks with a well balanced complete fertilizer like 10-10-10. If the plant gets leggy, pinch it back to 6 inches in height.

In late spring, repot into a larger container using a potting soil high in organic matter. After minimum night temperatures exceed 50°F move the poinsettia to a partially shaded site outdoors. Water and fertilize regularly. Keep the plants pinched back to two sets of leaves per stem. Do not pinch after the first of August.

Bring the poinsettia indoors before the first fall frost. Keep in a sunny window at room temperatures of 65 – 70°F. Fertilize every two weeks.

Poinsettias are short day plants meaning they need short day length and long nights to initiate flower buds. Beginning in late September, the plant must have complete darkness from 5 p.m. until 8 a.m. Cover the poinsettia with a light-tight box or put it in a closet every night until color shows in the bracts. During the day the plant must have bright light. Night temperatures above 70-75°F or light during the dark period will prevent or delay flowering.

The wide variety of sizes and colors in poinsettias make them perfect holiday decorations whether in the home or office. With care, your lovely plant should last through the winter and even brighten next year’s holidays.

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HIXTON, Wis. – Steady temperature and not overwatering are key factors in maintaining the health and wellness of Christmas poinsettias, says Jim Gathje, owner of Gathje’s Greenhouse at Hixton.

Gathje, who raises 5,000 poinsettias prior to Christmas each year, said extremes in temperature damage the plants. Poinsettia purchasers should avoid placing plants on the floor next to a door or near a heat register or other heat source. Poinsettias do not like drafts or anyplace too warm; high temperatures will shorten plant lives. They prefer daytime temperatures of 60 to 70 degrees and nighttime temperatures of about 55 degrees. If possible move the plant to a cooler room at night.

Neither do poinsettias like wet feet.

“The colder and darker the environment is, the drier the poinsettia should be,” Gathje said.

Churches, for example, may utilize poinsettias for decoration on Sundays — but the rest of the week may have the lights off in the sanctuary and the heat turned down.

Many potted poinsettias are in peat-based soil. Gathje said an easy way to tell whether it’s time to water the plant is that it will be light in weight. Punch holes in any foil around the pot so water can drain into a saucer, and discard excess water. Although poinsettia owners shouldn’t keep soil wet, it’s important to water when the soil is dry. Wilted plants – an indication of root rot — will tend to drop their bracts quickly.

According to University of Illinois-Extension, it’s a misnomer that poinsettias are poisonous. The Ohio State University research showed that a 50-pound child would need to eat more than 500 poinsettia leaves to suffer harm. Furthermore, poinsettia leaves taste awful. Pet owners, though, are cautioned to keep dogs and kittens from chewing on the plants, because poinsettia sap may cause nausea, vomiting and diarrhea.

Skin contact with poinsettia sap can sometimes produce a mild itchy rash, according to Mayo Clinic in Rochester, Minnesota. If that occurs, wash the area with soap and water. If sap comes in contact with eyes, it can cause redness and irritation. If that happens, flush the eyes with water. Anyone with a latex allergy might also have a skin reaction to the poinsettia’s milky sap because latex and poinsettias share several proteins. In the event of a more serious reaction, seek medical attention.

What most people think are “flowers” are actually bracts or modified leaves. The yellow flowers of cyathia are in the center of the bracts. Bract color is jump-started by darkness – 12 hours at a time for at least five nights in a row, according to University of Illinois horticulturists.

Poinsettias are native to Mexico. California is the top poinsettia-producing state in the United States. Poinsettias are also the best-selling potted plants. There are more than 100 varieties of poinsettias available, in a myriad of colors — though red is still the consumers’ favorite.

When purchasing a poinsettia, check its maturity. Check the true flower or cyathia at the base of the colored bracts. If the cyathia is green or red-tipped and fresh-looking, the “bloom” will hold longer than if yellow pollen is covering the flowers, according to the University of Illinois.

The No. 1 question about poinsettias is: “How do I encourage the plant to ‘re-flower?’” According to the University of Illinois, it must be kept in total darkness between 5 p.m. and 8 a.m. Start this about Oct. 1 and continue until color shows on the bracts – usually early to mid-December. Any little exposure to light can prevent “coloring.” Covering the plant with a light-proof bag and putting it in a closet might work to keep it in the dark for the set period. Nighttime temperatures above 70 to 75 degrees can also interfere with flowering. But trying to keep a poinsettia year-to-year usually isn’t worth the effort because the bracts won’t be the same quality as original ones when the plant was purchased.

Visit extension.illinois.edu for more information.

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  • January to March: Keep watering the poinsettia whenever the surface is dry.
  • April: Starting April 1, gradually decrease water, allowing the soil to get dry between waterings. Be careful that the stem does not begin to shrivel. This is a sign the plant is too stressed and is dying. In a week or two, when the plant has acclimated to this drying process, move it to a cool spot, such as the basement or a heated garage. You want to keep it at about 60 F.
  • May: In mid-May, cut the stems back to about four inches and repot in a slightly larger container, with new potting soil. Water it well. Place the newly potted plant back into the brightest window you have and once again keep it at a temperature of 65 to 75 F. Continue watering whenever the surface of the soil feels dry. Watch for new growth. Once new growth appears, begin fertilizing every two weeks with a complete fertilizer. Follow fertilizer label recommendations.
  • June: Move the poinsettia outside, pot and all. Keep it in a partially shaded location and maintain your watering and fertilizing schedule.
  • July: In early July, pinch back each stem by about one inch. This is to encourage a stout, well-branched plant. If left unpinched, the poinsettia will grow tall and spindly.
  • August: By mid-August, the stems should have branched and leafed out. Once again, pinch or cut the new stems, leaving three to four leaves on each shoot. Bring the plant back indoors and into your brightest window. Continue watering and fertilizing.
  • September: Continue regular watering and fertilizing. Make sure the temperature stays above 65 F.
  • October: Poinsettias are short-day plants, meaning their bud set is affected by the length of daylight. To rebloom, poinsettias need about 10 weeks with 12 hours or less of sunlight per day. You will have to artificially create these conditions and it’s crucial that you be diligent. Beginning October 1, keep your plant in complete darkness from 5 p.m. to 8 a.m. Any exposure to light will delay blooming. Use an opaque box or material to block out light. Many people place their plants in a closet, but if the light gets in through the cracks or if you open and use the closet, it will affect the bud set. Move the plant back to the sunny window during the daytime and continue watering and fertilizing.
  • November: Around the last week of November, you can stop the darkness treatment and allow the plant to remain in the window. You should see flower buds at this point.
  • December: Stop fertilizing about December 15. Keep watering and treat your plant the way you did when you first brought it home in bloom. If all has gone well, it should be back in bloom and ready to begin the process all over again.

It’s time to start preparing your poinsettia for Christmas bloom. Photo: Andy Mabbett, Wikimedia Commons

When fall officially starts, it’s time to start preparing your poinsettia (Euphorbia pulcherrima) for its Christmas bloom. Its flowering is stimulated by short days, that is days less than 12 hours long. (Actually, it’s the nights longer than 12 hours that stimulate bloom, but let’s not quibble over details, as the results are the same.) So anything that reduces day length in the fall, while still maintaining viable conditions (warm temperatures, occasional waterings, etc.), will probably give good results. It really will bloom again for Christmas, year after year, if you just give it a chance.

However, anything that artificially extends day length, such as growing it in a room you keep lit at night, will prevent it from blooming.

The “Put It Outdoors” Method

Some Internet sites suggest that the best way to get a poinsettia to rebloom is to put it outside in the fall (or to leave it outside if you had already put your plant out for the summer) and to leave it there until the bracts start to change color. And that certainly sounds easy enough to do. After all, it will automatically receive short days outdoors from September 22 on (thank you Mother Nature!). So unless you place it near a lighted window, street lamp or other source of night illumination that will artificially extend day length, it really ought to start changing color in November… and once the color change is initiated, it will continue even if the days are no longer short. So you can bring your just-starting-to-bloom poinsettia indoors where it will complete its blooming cycle.

Leaves dropping shows your plant is reacting badly to the change.

There is a major flaw with this technique, though. Poinsettias are all right at fairly cool temperatures, but dislike cold (less than 45˚F/7˚C) and frost will kill them back to the base, if indeed it doesn’t kill them outright. So if you live in an area where temperatures can dip below 50˚F (10˚C) in October or November, and that would cover all of pretty much all of North America north of Florida as well as all but the Mediterranean region of Europe, leaving poinsettias outside in the fall is inherently risky.

But it’s not just the risk of cold or frost you have to consider.

Poinsettia plants that acclimate to cool fall temperatures outdoors tend to shed their leaves massively when you do bring them back indoors. They find the transition from cool conditions to warm ones a severe shock. So yes, your plants will bloom, but sans most of their leaves. Not too charming an effect!

The Easy Way

To get a poinsettia to bloom with a full cohort of leaves, first bring it indoors early in the fall, while night temperatures indoors and out are pretty much equal. That way the plant will already be acclimated and won’t lose leaves. Then all you have to do is to give it short days indoors (and keep watering it, of course)… and that’s a snap. To learn how, see Blooming a Poinsettia the Laidback Way). Try it: it really works!

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