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Growing in the Green: February 2010

January 28, 2010  By Melhem Sawaya

Growing any crop for a certain shipping date has its own lessons to be
learned. Growing poinsettia for a shipping date that spans from early
November to Dec. 23 has unique lessons every season

Weather was a major factor this year for Ontario growers and for consumers

Growing any crop for a certain shipping date has its own lessons to be learned. Growing poinsettia for a shipping date that spans from early November to Dec. 23 has unique lessons every season. Here are some of the challenges growers have to deal with every poinsettia season:

Ron and Mark Miziolek, and John Robero, of Waterloo Flowers, like ‘Ice Crystal.’

The results of a PGR overdose.
A slight cool draft can delay a crop by two weeks.
This cat’s main diet, apparently, is poinsettia.
Michelle Veit, of Sonnyside Flowers near Delhi, loves the ‘Prestige’ variety.
Looking for an excellent rooting variety, try ‘Polly Pink.’
Upgrading poinsettia plants pays off with consumers.
‘Enduring Pink’ (at left) and ‘Classic Pink’ are impressive.
‘Classic White’ and ‘Premium Polar White Bear’ are strong performers.
‘Premium Ice Crystal’ was a hit this past season.
‘Ice Punch’ is another hit variety for the 2009 season.    
Mickey Ferragine of Bradford Greenhouses, just north of Toronto, likes the ‘Mars Tri-colour.’
If whiteflies were shipped to you with the cuttings, they were with you the entire crop, whether you tried to control them chemically or biologically.
‘Cortez Burgundy’ is largely only popular with fundraisers.
Andy and Pete Vander Hoeven, of Vander Hoeven Greenhouses in St. Catharines, greatly admire ‘Classic White.’
The ‘Classic Series’ would work well in tri-colour programs.    
The ‘Novia’ variety at left is growth regulated; on the right is the control.
Jeremy Van Koeveringe, of Spring Valley Gardens in St. Catharines, likes what he sees in ‘Classic Pink.’
Keagan and Logan Jeffries, of Warren Greenhouse in Kitchener, are appreciating poinsettia at an early age.
‘Visions of Grandeur’ is my favourite poinsettia.
Value-added poinsettia enjoy great sales.    
Sales of greens were excellent due to the nice fall weather.    
Exceptionally large bracts were due to the excellent weather this fall.    
Roger Kehoe, of Ecke Ranch, is showing off ‘Visions of Grandeur’ during a visit to Linwell Gardens in Beamsville    
‘Enduring Pink’ still puts on an excellent show when bracts develop.    
Jagoda Jankowiak, of Linwell Gardens, with ‘Premium Picasso.’    
Linwell Gardens growers Jeff Groen (at left) and Thomasz Jankowiak (at right), with Roger Kehoe of Ecke Ranch in a sea of ‘Prestige’ poinsettias.    
Pete and Paul Vos, of Vos Floral in Freelton (near Hamilton), are big fans of ‘Ice Crystal.’    
‘Polly’s Pink,’ ‘Pink Cadillac’ and ‘Classic Pink’ are strong performers.

  • An ever-increasing number of new varieties.
  • Lack of practical culture information on how to grow the new cultivars.
  • If
    there was some culture information, it pertains to only certain
    geographic areas and not to all – which makes it more confusing.
  • The
    weather is never the same from one year to the next, so trying to
    follow the same environmental parameters each year could be disastrous.
  • Introduction of a new soil mix without any proper testing.
  • Introduction
    of a new chemical (pesticide, fertilizer, wetting agent or any other
    new product) without much (or any!) testing, which results in thousands
    of dollars in shrinkage. N.B. – The number one shrinkage factor
    in the horticulture industry, in my opinion, is the introduction of new
    products without proper testing.

Introducing a new cultivar to the buyer, which was forced on the grower, leads to growing a crop with lots of advertising money spent on it, but a product that cannot be delivered by the grower because:

  • Its newness creates growing challenges.
  • We do not know the consumer appeal for that cultivar.
  • The breeder or variety broker is not ready to ship quality cuttings to the grower and the grower doesn’t know exactly how to grow that specific crop because it is also new to them.

So, before trying a new cultivar on a large scale, test it for production know-how, customer appeal (which is more important), and shipping and shelf life at the consumer level.

This past year was a different year for both poinsettia sales and production in Ontario, due to the weather. Sales started slowly, but by season’s end, the entire crop was sold. This is the third year production met market demand. However, I hasten to add that the few growers who increased production by five per cent still had that five per cent in their greenhouses at the end of the season.

There are a few growers who still grow their poinsettia crop on speculation, hoping that some grower/broker will take it off their hands. This didn’t pan out either, and for the following reasons:

  • The season started late and every grower/broker naturally wants to ship their own crop and, if they need more product, they will try to find it.
  • The weather was perfect for bud-set because the temperature in late September (when bud-set is supposed to take place) was perfect.
  • In October and November, we had the highest light levels I can remember over the last 30 years.

The combination of both of these weather conditions led to having many varieties ready to ship Nov. 5-7 which, with normal natural light levels, would not have been ready until Nov. 25 or so.

With the exceptionally good weather, people were not thinking of indoor decorations when outdoor temperatures were in the teens. On the other hand, greens sales increased by 10 to 20 per cent.

The early bud setting and large bract development led to cultural problems at the end of the shipping dates due to overly mature bracts that showed damage that is referred to as bract edge burn.

Bract disorders have many causes; it’s not just calcium deficiency. The connection between calcium deficiency and bract disorders overshadows other causes because some tests show that sprays of calcium can minimize the symptoms. As growers, we mainly concentrate on how to correct the problem rather than how to prevent it – just like taking Aspirin, Tylenol or some other medicine instead of finding the reason for the headache.

I used to get severe headaches but only on the weekends and, yes, I took the pain pills and felt drowsy, but without pain. Then, for some reason, I decided to switch from caffeinated to decaf coffee and, after three weeks, the weekend headaches disappeared. I realized that the cause of my headaches was the sudden withdrawal every weekend from the normal six to eight cups of caffeinated coffee I drank each weekday, to the weekend, when I drank no coffee at all!

Going back to plants, another example of correcting the symptoms rather than preventing the cause, is applying iron chelate to counter yellow tips on calibrachoa or petunias. Just as there are many ways to prevent yellowing on calibrachoa, so too are there strategies to prevent bract edge disorders on poinsettia. Here are a few of them:

Reduce humidity in the greenhouse – If humidity is too high, the plants are getting most of the moisture in the air on their leaves, so the roots don’t have to work as much, or hardly at all. This means nutrients we provide are not getting to where they belong.

The worst scenario is when we use flood floor irrigation, or some other kind of subirrigation, where the heat is delivered primarily from the bottom, which evaporates much of the water from the pot and builds up humidity. This humidity damages the root tips, which then prevents the nutrient uptake, leading to some nutrient deficiencies.

That is why many greenhouses – mainly vegetable greenhouses – have suspended heat pipes installed with adjustable cables to enable them to position the heat just above the leaf canopy so the plant will work on absorbing all nutrients provided to them.

Use a media that drains well – Well-draining media is used to avoid root growth without the hairs that are the implement of nutrient transportation. It is what I call “avoiding swamp roots.”

Maintain good root growth –
Establish a healthy root system early on in the crop, because a strong, well-rooted plant will withstand minor, unfavourable growing conditions.

Reduce fertilizer EC – High salts at the finishing stages of the crop could lead to bract disorders if the crop dries up too much.

Avoid pesticides on bracts – Some pesticides, such as thiodan, if applied at bract colouring or even earlier, could and will cause bract edge disorder.

Balance fertility – Maintain proper ratios of potassium, calcium and magnesium. It should be: potassium = 3; calcium = 2; and magnesium = 1. However, the total EC for the last three weeks should be 0.5 to 0.6.

Provide a calcium uptake environment – Make every effort to ensure the nutrients are being taken up by the roots. For example, horizontal airflow fans are important for two main reasons: they provide a gentle air movement that will encourage evaporation that will then encourage nutrient uptake; and they will even out the temperature throughout the various locations in the greenhouse.

Also, make sure the pH is from 6.0 to 6.5, because calcium is not available at low pH levels.

It’s also important to select cultivars that are resistant to bract edge burn.

If all this fails, some experiments have shown that spray applications of calcium could be helpful. A spray of 300 ppm to 400 ppm of calcium will supplement calcium buildup in the bracts. Spraying the bracts has to happen when leaf temperatures are not very high and it is better to spray early in the morning to allow the bracts to dry before sunset. If you decide to spray calcium, use only a high-grade purity of calcium.

To take full advantage of the calcium sprays, you must start spraying as soon as the bract colour shows and continue spraying every six to seven days until pollen shed.

If we learned anything from this season’s poinsettia crop, it was that 10 per cent of sales were from Nov. 10 to 24, some 80 per cent from Nov. 25 to Dec. 10, and the remaining 10 per cent from Dec. 11 to 20.

This month’s major take-home lesson is that old, ripe bracts are a cause for problems, and timing the crop according to these projections is an important aspect of a successful season. ■

Melhem Sawaya of Focus Greenhouse Management is a consultant and research coordinator to the horticultural industry. Comments on this or any other article are always welcome; please e-mail, or visit or .

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