Understanding Plant Nutrition: Poinsettias

Understanding Plant Nutrition: Poinsettias

Profit margins are extremely tight for poinsettias, so minimizing shrinkage that results from crop losses is essential. If nutritional stress occurs, you will be struggling from that point onward to produce a high-quality plant for sale.

Poinsettias hang around your greenhouse for several months, much longer than short-term spring crops. Therefore, a preventative approach that breaks the crop down into stages can help avoid the usual problems. Here are some pointers to consider at each stage.

Pointers

1. Poinsettias have four stages in which fertilizer needs vary: propagation, initial growth, rapid growth and flowering phases. Figure 1 represents the goals in each stage. The amount of fertilizer taken up by plants varies depending on how quickly the crop is growing.

2. During propagation, avoid solutions that have a high electrical conductivity (EC) (above 0.75 mS/centimeter) or fertilizers containing phosphorus to avoid foliar damage (Figure 3). Rooting can be delayed as mist-water EC increases, so use your purest water quality for propagation.

If stock plants were adequately fertilized, fertilizer is not necessary during the initial mist phase. If tissue nutrient levels in cuttings begin low (Figure 3), then it will be more important to apply nutrients early during propagation.

3. After one soil volume of water is leached out the bottom of the pot, any pre-plant nutrient charge contained in the growing medium will have been removed. Once roots emerge and misting is reduced, consider recharging nutrients with around 200 to 400 parts per million of nitrogen (ppm N) applied with a thorough irrigation to recharge the soil solution.

4. Control fungus gnats and pythium throughout the crop. Nutrient uptake is completely dependent on having a strong root system. If roots get stressed through pests, disease, high EC or overwatering, you will run into slow growth and sometimes deficiency symptoms.

5. During early growth, poinsettia elongation should not be “pushed” with extra fertilizer. Figure 4 shows an example of an experiment where fertilizer was either gradually increased (scheduled), or remained high throughout the crop (at 400 ppm N). Root systems were much stronger with a gradual increase in fertilizer EC.

6. Trends in media-EC with weekly in-house tests help you refine the fertilizer concentration. Choose whatever soil-test method you find most convenient and use the appropriate target EC values (pour-thru (1.9 to 4.1 mS/cm), 1:2 (0.6 to 1.5 mS/centimeter) or saturated medium extract (1.1 to 3.0 mS/centimeter)).

The fertilizer ranges in Figure 1 provide a reasonable guide, but we have provided a range not just to be vague, but because the “best” fertilizer rate depends on a number of factors in your situation. For example, light-colored foliage plants tend to require a higher fertilizer rate than dark-leafed cultivars. Slow-growing cultivars, such as variegated and Winter Rose types, have greater leaf expansion and vigor with moderate, rather than high, fertilizer rates.

Irrigation practices also have a big effect on required fertilizer concentration. For example, research at Michigan State University showed poinsettias could be adequately fertilized either with 100 ppm N and no leaching (such as subirrigation), or 400 ppm N with 55 percent of solution leached with each irrigation. Fertilizer rates in Figure 1 represent constant fertigation (fertilizer applied with each irrigation). If you apply regular clear water or fungicidal drenches, a higher concentration is needed whenever you do fertilize.

7. Target pH levels for poinsettias are broad (ideally between 5.6 and 6.4) because poinsettias are not as sensitive to media-pH issues as some other crops, such as petunia and geranium. At the extremes, however, symptoms of micronutrient deficiency or toxicity can occur.

8. Remember, the total nutrient solution is a combination of your irrigation water and the fertilizer solution. Therefore, the ideal poinsettia fertilizer varies between locations depending on irrigation water quality. For growers with high calcium and magnesium rates in their irrigation water (60 to 80 ppm and 30 to 40 ppm, respectively), that is already at the level of most calcium-magnesium fertilizers. However, growers with more pure irrigation waters will need to use a fertilizer high in NO3-N that also contains both calcium and magnesium.

9. Calcium and magnesium can also be supplemented to avoid deficiency symptoms (Figure 5) and also to reduce botrytis infection of foliage. Calcium can be applied as foliar sprays during the bract expansion phase. The Paul Ecke Ranch, Ecke.com, has a detailed bulletin on calcium sprays in its Tech Help section. Monthly soil drenches with magnesium sulfate (Epsom salts) at 1 pound/100 gallons supplement magnesium. Do not combine magnesium sulfate with calcium fertilizers such as calcium nitrate in the same concentrated tank, or precipitation will occur.

10. As the crop approaches the middle of October, avoid fertilizers that have most of the nitrogen in the ammoniacal or urea form, for several reasons: (a) most ammonium-based fertilizers are low in calcium and magnesium; (b) there can be increased soft growth with ammonium; and © in extreme cases with cool temperatures and dark conditions, ammonium toxicity can sometimes occur (which appears as a marginal chlorosis and downward cupping leaves).

11. Post-production quality for the consumer is improved when media-EC levels are low at the end of the crop. Growers sometimes cut off fertilizer too early in production, leading to deficiencies during bract expansion. A safe approach, especially if you are growing multiple cultivars in the same irrigation zone that mature at different times, is to drop fertilizer level to around 100 ppm N for the last two to three weeks.

Conclusion

In reality, poinsettias tolerate a wide range of nutritional levels. You can grow by the seat of your pants and usually get away with it. However, when you can’t afford a mistake, it’s good review your fertilizer strategy for each of the four stages of production.

Leave a Reply

One comment on “Understanding Plant Nutrition: Poinsettias

More From ...

August 4, 2015

New 2015 California Spring Trial Edibles For The Patio And Garden

If you are looking to capitalize on the foodie trend and spread your risk beyond Spring sales, new vegetables showcased at 2015 California Spring Trials offer plenty of opportunities to focus on unique, flavorful vegetables and edible plants that also hold ornamental value. Here are a few of new varieties Editor Laura Drotleff and Group Editor Carol Miller discovered at Spring Trials that will help diversify your crop mix.

Read More
Roots To Re-Entry’s ornamental plant nursery donates plants to local community gardens

August 4, 2015

Roots To Re-Entry Transforms Lives

An inspired employment initiative takes green-job training behind prison walls to help inmates find jobs in urban agriculture and the landscaping industry upon their release, and along the way, it is changing lives for the better. The Roots To Re-Entry (R2R) job training program, conceived by the Pennsylvania Horticulture Society (PHS) and its partners, does more than teach inmates of the Philadelphia Prison System the skills they need to find meaningful employment; it also teaches them invaluable life skills. The PHS staff leads participants through a 16-week course that includes hands-on projects designed to teach them horticultural skills and provide them with training in landscape maintenance and greenhouse growing. In addition to English and math, the nonprofit Federation of Neighborhood Centers (FNC) offers supplemental courses in health education and employment preparedness. Upon inmates’ release from prison, the FNC assists R2R graduates with the transition to life outside prison walls by […]

Read More
Oso Easy Lemon Zest rose_featured

August 4, 2015

Oso Easy Lemon Zest Rose Honored With Award Of Excellence

The American Rose Society (ARS) announced at the 2015 National Conference that Proven Winners received the Award of Excellence for Oso Easy Lemon Zest rose. To receive the Award of Excellence, a rose must prove itself in six different no-spray trial locations across the U.S. This is the second Proven Winners rose to win this prestigious award; Oso Happy Petit Pink rose received the Award of Excellence in 2012. “We are thrilled to receive this award from ARS for Oso Easy Lemon Zest, as its one of our favorite roses and a top seller,” says Tim Wood, product development, Spring Meadow Nursery. “A healthy-growing, self-cleaning rose that does not fade to white has been on a lot of people’s wish list, and this award confirms that this is a very special rose.” The Oso Easy Lemon Zest rose was developed by Chris Warner, the highly acclaimed rose breeder from Shropshire, England. […]

Read More
Latest Stories

August 4, 2015

New 2015 California Spring Trial Edibles For The Patio …

If you are looking to capitalize on the foodie trend and spread your risk beyond Spring sales, new vegetables showcased at 2015 California Spring Trials offer plenty of opportunities to focus on unique, flavorful vegetables and edible plants that also hold ornamental value. Here are a few of new varieties Editor Laura Drotleff and Group Editor Carol Miller discovered at Spring Trials that will help diversify your crop mix.

Read More
Roots To Re-Entry’s ornamental plant nursery donates plants to local community gardens

August 4, 2015

Roots To Re-Entry Transforms Lives

An inspired employment initiative takes green-job training behind prison walls to help inmates find jobs in urban agriculture and the landscaping industry upon their release, and along the way, it is changing lives for the better. The Roots To Re-Entry (R2R) job training program, conceived by the Pennsylvania Horticulture Society (PHS) and its partners, does more than teach inmates of the Philadelphia Prison System the skills they need to find meaningful employment; it also teaches them invaluable life skills. The PHS staff leads participants through a 16-week course that includes hands-on projects designed to teach them horticultural skills and provide them with training in landscape maintenance and greenhouse growing. In addition to English and math, the nonprofit Federation of Neighborhood Centers (FNC) offers supplemental courses in health education and employment preparedness. Upon inmates’ release from prison, the FNC assists R2R graduates with the transition to life outside prison walls by […]

Read More
Oso Easy Lemon Zest rose_featured

August 4, 2015

Oso Easy Lemon Zest Rose Honored With Award Of Excellen…

The American Rose Society (ARS) announced at the 2015 National Conference that Proven Winners received the Award of Excellence for Oso Easy Lemon Zest rose. To receive the Award of Excellence, a rose must prove itself in six different no-spray trial locations across the U.S. This is the second Proven Winners rose to win this prestigious award; Oso Happy Petit Pink rose received the Award of Excellence in 2012. “We are thrilled to receive this award from ARS for Oso Easy Lemon Zest, as its one of our favorite roses and a top seller,” says Tim Wood, product development, Spring Meadow Nursery. “A healthy-growing, self-cleaning rose that does not fade to white has been on a lot of people’s wish list, and this award confirms that this is a very special rose.” The Oso Easy Lemon Zest rose was developed by Chris Warner, the highly acclaimed rose breeder from Shropshire, England. […]

Read More
Heating Roundup Feature Image

August 1, 2015

5 New Heating Options For The Greenhouse

Five heating systems manufacturers share their latest and greatest products. Tubing And Aluminum Heat Pipes (BioTherm) From Megatube and MicroClimate tubing to DuoFin and StarFin aluminum heat pipe, BioTherm is dedicated to providing heat solutions that can withstand the toughest greenhouse environments. The MegaTube and MicroClimate tubing options are easy to install and ideal for bench or floor heating. The tubing has a conductive heating surface that allows for maximum root-zone heating. The DuoFin and StarFin aluminum pipe options are great for perimeter heating and melting snow trapped in the greenhouse gutter. It can also be useful for bench heating. Both pipe options provide gentle, radiant heat for plants and don’t require welding. TrueLeaf.net Infinite Energy 2 Condensing Boiler (Delta T Solutions) With up to 98 percent efficiency, the IE2 condensing boiler boasts a stainless steel heat exchanger with larger waterways to ensure maximum heat transfer. The product’s design ensures flexibility while […]

Read More
Basil_Persian-AAS2015_620x329

July 31, 2015

All-America Selections Promotes Garden-Fresh Cooking

All-America Selections (AAS) has stepped forward with another first when promoting AAS Winners, this time in the form of cooking videos using vegetables/edibles that have performed extremely well in the AAS Trials. These days, a love of gardening is directly related to a passion for cooking. Tying the two together is a natural when marketing joys of cooking with fresh vegetables from the garden and farm market. After 82 years of conducting trials where only the best performers are declared AAS Winners, the organization now has more than 325 individual varieties that have been “Tested Nationally & Proven Locally.” It is some of these many varieties that culinary storyteller, entertainer and horticulture industry veteran Jonathan Bardzik will use in a series of five videos demonstrating cooking techniques with AAS Winning herbs and vegetables. “I am excited to partner with All-America Selections to show people across the country that AAS Winners perform […]

Read More
Burpee Home Gardens Brand Adds Flowers

July 31, 2015

4 Reasons Retailers Snub National Brands

Greenhouse Grower’s lead editor, Laura Drotleff, and I got into a debate about why garden retailers, especially independent garden centers, snub marketing efforts from breeders and growers. She was very much on the breeders’ and growers’ side, expressing frustration about how limited retailers’ vision can be on the topic. I’ve reported on the garden retail side of the industry since 1998, about the same length of time Laura has reported on growers. I’ve heard a lot of retailer views on this, so allow me to share the most common reasons why retailers decline free marketing: Costs. While the marketing materials are free, and sometimes advertising, participating in these projects usually requires minimum orders. From a grower’s perspective, the minimum orders are reasonable. If garden stores promote a plant line, they need to have enough supplies to satisfy demand. From a retail perspective, if inventory reports show a plant line can […]

Read More
llan Armitage Syngenta Starcluster

July 30, 2015

Let’s Talk About Starflowers. Why Is Pentas Not More Po…

It is good to talk about production techniques, performance results and then to see how our friends garden. Diversity of plant material has always been a strength in American garden centers, and we should never run out of plants to get people excited. However, perhaps people are tired of Petunias or Callas or Geraniums, but we will never run out of options to put in front of them. One plant that is often overlooked is Pentas, a fabulous summer crop for late spring sales. These are heat-tolerant plants, and growing them below 65°F in the greenhouse results in significant delay. Fertility should be at least 150ppm nitrogen, but avoid ammonia in the fertilizer. Plants are best grown at a somewhat higher pH than usual, between 6.4 to 6.8. For best presentation, pinch out the center bud. Side flowers will bloom together, and plants will walk off the shelf. Garden centers […]

Read More

July 30, 2015

Spread Your Risk Beyond Spring Sales [Opinion]

Growers who participated in Greenhouse Grower’s 2015 Spring Crops Recap Survey said they have had enough of the uncertainty that the weather brings. They said it’s time to build up sales in other seasons like fall so we’re not so dependent on spring. As a couple of wholesale growers, both from the Southeast, very eloquently stated, our industry has mastered squeezing everything we can out of the spring season. And while this year happened to be a very successful one, thanks to the improving economy and elevated consumer confidence, they said, “now is no time to celebrate.” “Spring is still Christmas in the horticulture industry, but we have done such a good job focusing on spring that we have neglected other seasons,” one grower said. “Having so many eggs in the spring basket is dangerous. Fall will never be what spring is, but having a solid second season is in […]

Read More
Mike McGroarty, owner of Mike’s Backyard Nursery

July 29, 2015

Backyard Success: Mike McGroarty Educates Aspiring Grow…

Mike’s Backyard Nursery sits on a long, narrow, 5-acre property located in Perry, Ohio. There, customers can find a variety of flowering shrubs available, all in 2-quart pots, and all for sale for $5.97 each. Owner Mike McGroarty, a lifelong resident of Perry, says the town has a lot of plant nurseries, including 100 wholesale growers within a 10-mile radius of his house. That doesn’t discourage McGroarty, because he knows that while there are a lot of nurseries in his area, no one else is doing what he is doing. McGroarty has learned about plants — and marketing them to his audience — through decades of experience. He has never hesitated to pass along his knowledge to other growers looking to start their own backyard operations, and has created an entire program to educate aspiring growers. McGroarty Likes To Practice What He Preaches McGroarty’s operation serves as the laboratory for […]

Read More

July 29, 2015

2015 Spring Crops Report: Rain Soaks Spring Sales

Rain, rain and more rain. That was the story this spring for the large majority of growers across the U.S. And where it wasn’t too wet, it was too dry. Drought conditions cut sales in the West and Southwest. But it wasn’t all bad. Eighty-nine percent of respondents to Greenhouse Grower’s 2015 Spring Crops Survey declared the season a success, despite its challenges. They said beautiful weather in April and excited consumers who were ready to spend got the season going early, but then cool temps and rainy weekends throughout May and June caused confusion over when and how much to plant. Of the 189 respondents to Greenhouse Grower’s 2015 Spring Recap Survey, 53 percent identified themselves as grower-retailers, 34 percent were wholesale growers and 13 percent said they were young plant growers. Most responses came from the Midwest (27 percent), Northeast (18 percent) and Southeast (16 percent), but also […]

Read More

July 29, 2015

Dümmen Orange Continues To Strengthen Standards With MP…

MPS recognized Dümmen Orange during an unofficial ceremony at Cultivate’15 for its continued dedication to ensuring sustainability in the floriculture industry. Through its deep understanding of environmental impact and the importance of sustainable operations, Dümmen Orange has implemented production best practices within its facilities to meet or exceed MPS standards on environmental and agricultural practices, as well as social responsibility. “Nowadays, consumers are not only interested in the visible and tangible characteristics of the products they buy, they also are concerned with how products are made,” says Carl Kroon, General Manager of the Dümmen Orange farm Las Mercedes in El Salvador. “Dümmen Orange is deeply rooted in our commitment to our people, our values and our planet. The MPS certification helps us to make it visible to our customers that our production methods respect our workers and the environment.” Setting A High Standard Dümmen Orange has taken a wide range […]

Read More
cultivate'15 logo

July 29, 2015

Participants From All Over The World Gather At Cultivat…

Participants from the United States, Canada, Mexico and more than 20 other countries gathered in Columbus, Ohio for Cultivate’15 on July 11-14. The largest all-industry horticulture exposition and convention in North America recently concluded with approximately 10,000 attendees. This year, attendees saw more exhibitors, an expanded collection of business-building programs and the presentation of several industry initiatives. The event gathered professionals from all aspects of the horticulture industry, including garden and floral retailing, greenhouse and nursery production, plant breeding, landscaping, interior plantscaping, research and education and the manufacturers and distributors of products and services. Formerly known as the OFA Short Course, it was the 87th edition of the event that was rebranded last year as “Cultivate.” Michael V. Geary, AmericanHort president and CEO, says the event continues to grow and serve the diverse businesses that comprise the industry. “Cultivate is not just a grower show anymore, and hasn’t been in contemporary […]

Read More
Bob_Peters

July 28, 2015

J.R. Peters’ Founder Dies At 97

J.R. Peters announced that its founder, Robert (Bob) Peters has died. Here is how his family and coworkers honored him: It is with great sadness that we announce the passing of Robert (Bob) Peters, 97 years old, founder of the Robert B Peters Company. Our mentor, father and grandfather passed away peacefully surrounded by his family on July 18 in Allentown, Pa. He was a true floriculture chemist who designed and formulated the earliest Peters Fertilizer Products that still carry his name today. Born October 12, 1917 in Hanover, Pennsylvania, he was the oldest of 6 brothers. He made his home in Allentown where he started his first business, Peters Horticultural Services, in his mother’s garage in 1947. Bob was happily married for over 50 years and has 4 children, 13 grandchildren and 7 great grandchildren. His passion for plant nutrition began in 1947 after he completed his service in […]

Read More
2016 SHSG covers.indd

July 28, 2015

SHS Griffin Releases 2016 Catalog In Print And Expanded…

SHS Griffin has announced the release of its annual seed and plant catalog for the 2015-16 season. Available in both print and digital formats, the 2016 catalog features more than 400 new and improved varieties from the industry’s leading breeders. The 262-page print catalog covers the company’s full seed portfolio — more than 3,400 cultivars of annuals, perennials, ornamental grasses, herbs and vegetables. From the SHS Griffin vegetative offering, the complete spring-annual assortment from Syngenta Flowers is featured, alongside new introductions and top sellers from nine top suppliers such as Proven Winners, Dümmen Orange and Suntory. More than 120 vegetative perennials from Syngenta Flowers are also included, including several SHS Griffin exclusives. The SHS Griffin 2016 digital catalog includes all of the product information and photography from the print edition, and more. For the first time, SHS Griffin has added a range of digital-only bonus content: detailed crop culture, quick […]

Read More
Cal-Poly fields

July 28, 2015

Cal-Poly To Preserve Campus Agricultural Land

California Polytechnic State University, San Luis Obispo will no longer consider development of nearly 43 acres of prime agricultural land just west of its campus core, as the university proceeds with the two-year process of updating its campus master plan. In May, the university had released an update to its Master Plan that indicated that almost all of its orchards, horticulture facilities and field sites may be repurposed for future development of university housing and other campus infrastructure. Most of the land in question is classified Class 1 farmland. The acreage is used now for lemons, grapevines, mandarin oranges, a deciduous orchard and silage for the university’s livestock. The proposed changes would have directly affected the current orchard plantings and other long term plans for the department, according to a letter from Scott Steinmaus, the horticulture and crop science department head. Steinmaus encouraged industry members to submit their comments to the university. An […]

Read More
Syngenta CAST 2015

July 27, 2015

New App Brings Syngenta Flowers’ Portfolio To Gro…

Syngenta Flowers' newest app allows growers and brokers to quickly access information, descriptions, photos, culture and more on all of Syngenta's varieties.

Read More
Heating Feature image

July 27, 2015

In Hot Pursuit Of Heating Trends For The Greenhouse

From biomass boilers to hydronic-heating systems, growers have a range of options to fit their operation’s unique needs. Here’s what five manufacturers had to say about the latest trends.

Read More
Suzanne McKee

July 27, 2015

ePlantSource’s Suzanne McKee To Hike Grays Peak T…

Just a few years after welcoming their two daughters into the world, Gordon and Kristen Gray are faced with the agonizing diagnosis that their girls, Charlotte and Gwenyth Gray, both have Batten Disease CLN6, a rare neurodegenerative disorder that currently has no cure and is fatal. Children afflicted with this usually do not survive past the age of 12. Since the diagnosis, the friends and family of the Grays, including Suzanne McKee from ePlantSource, have come together to show an enormous amount of support through viral social media campaigns, silent auctions, lemonade stands and various other events and fundraisers. Celebrity support has also come in droves from celebrities such as Ali Larter, Channing and Jenna Dewan Tatum, Drew Barrymore, Dwayne Johnson, Eva Longoria and countless others. The Colorado friends of the Gray family are hiking Grays Peak on August 29 in support of Charlotte and Gwenyth. McKee and Brooke Michaels […]

Read More