Technical Information Bulletin

SUBJECT: "Toning" Poinsettias for Improved Finished Quality

Growers can increase the post-production longevity of their poinsettia crops by conditioning plants or "toning" them to become more durable. Other benefits of toning include a decreased incidence of production disorders such as bract edge burn, stem breakage and rapid loss of foliage and flower cyathia. While these problems may be more prevalent in specific regions of the country, no grower is safe from any one, or combination of these disorders. By adopting a philosophy of "toning" crops throughout production, growers can take the initiative to avoid these crop problems. Increased quality, profitability and consumer satisfaction should be the result of these efforts. Changes in cultural practices at particular stages of production are a way to accomplish toning.

Specific Production Recommendations
Pinching:	Avoid developing excessive branches (and bracts) by not pinching too high. A poinsettia with 5 blooms can give as much color show as a plant with 8. The production of more branches and bracts on a single plant will result in these branches/bracts being smaller and weaker.
Light Intensities:	Provide full light intensity (4,500 to 5,000 foot candles/48,200 to 53,800 lux) as long as excessive daytime temperatures can be avoided. Benefits include increased stem strength, post production longevity and decreased internode length.
Temperatures:	Once cuttings are established and pinched, with branching evident, maintain temperature levels at a consistent level appropriate for the cultivar being produced. For most poinsettias, an acceptable night temperature is 64-66°F (18-19°C). Day temperatures will vary with region of the country. Growers in the southern region of the United States should try to maintain day temperatures of 85°F (29°C) or below. Growers located in the northern and central regions should try to maintain day temperatures of 75-80°F (24-26°C).
Fertilization:	Maintain constant fertilization levels of 200 to 250 ppm nitrogen for established cuttings that are actively growing. Monitor crop nutrition through soil and tissue testing. This will assist the growers with maintaining soluble salt levels (EC), pH and nutrient status at appropriate levels. By mid-October, eliminate any urea and minimize ammonium form of nitrogen from the fertilizer program and maintain the EC levels in the growing media below 3.0. If using slow-release fertilizers, be sure to choose formulations that will have released all the nutrients before full bract maturity.
Irrigation:	Avoid lush soft growth that results from over-watering the crop. Good soil moisture management will reduce internode stretch, increase stem stiffness and minimize the incidence of root rot organisms attacking the crop.
Plant Growth Regulators:	Use plant growth regulators as needed to avoid extensive internode stretch and then stems at the point where the side shoots connect to the main stem.

Finishing Tips

As poinsettia crops enter the final stages of production, give special attention to cultural practices and greenhouse conditions that are appropriate for finishing the crops. The process of toning does not end until the plants have all been shipped.

Maintain normal temperatures (75-80°F/24-26°C day temperatures, 64-66°F/18-19°C night temperatures for most cultivars) throughout bract expansion and development. Higher day and night temperatures contribute to bract edge burn and premature cyathia drop. Until the plants have fully colored bracts (primary and secondary bracts), do not reduce temperatures on the crop. Avoid dropping temperatures below 58°F (14°C) after bract formation.

Maintain good ventilation and air circulation in the greenhouse to lower relative humidity to 90% or less. Bract edge burn can result from reduced root activity and restricted water uptake that occurs under conditions of high humidity. Conditions of high humidity favor Botrytis which can easily attack soft bract tissue during the final stages of development. Growers have found the use of horizontal airflow fans beneficial to enhance air movement, increase transpiration and even temperatures. Maintain good soil moisture management throughout the finishing stages of growth. Constantly wet soil will restrict root activity, increase the potential of root rot organisms, and result in softer plant tissue that is susceptible to damage.

Maintain full light intensities on the crop until primary bracts have fully colored and secondary bracts are near maturity. Any reduction of light before this stage will reduce bract color and slow development. Shading to 2000 foot-candles/21,520 lux after the bracts have matured prevents fading and potential damage from sunburn.

Eliminate all fertilization 2-3 weeks before the crop becomes fully mature and ready for sale. Excessive soluble salts in the media contribute to bract damage and reduce post-production longevity.

©1999 Paul Ecke Ranch All Rights Reserved	.
We hope the information provided will be helpful. It is based upon data and knowledge ( including information provided by the recipient) considered to be true and accurate, but without independent investigation and is offered for the recipient's consideration, investigation and verification, but we do not warrant the results to be obtained. Please read all statement, recommendations, or suggestions in conjunction with any conditions of sale or use which apply to any products, or systems recommended by us. No statement, recommendation, or suggestion is intended for any use which would infringe any patent/copyright.