January 2025 Breeder News, Culture, Variety Info

Culture Report: Poinsettia ‘Red Ribbons’ By QiuXia Chen

Ruth Kobayashi brings innovation to the poinsettia market with ever-branching genetics. These poinsettia varieties are bred for improved branching capabilities to produce a plant that does not require manual tip removal. 

The first of its kind to be on the market, ‘Red Ribbons’ showcases a vibrant and abundant cyathia presentation on deeply, oak-leaf shaped bracts. It’s a trial garden favorite that offers versatility with an 8-week response time and compact vigor. Its distinct characteristics pair nicely in foliage combinations to deliver a wintry tropical mix with texture and contrast compared to a traditional all poinsettia mixed combo. 

PROPAGATION 

Upon receipt, open cuttings and stick immediately. If cuttings cannot be stuck upon arrival, store them in a cooler at 50-55° F with near-100% humidity. Mist cuttings with water if they appear wilted or dry. 

Lighting 

Light levels should be maintained no higher than 1,000 footcandles (6 mols/ day) during the first 1-2 days after sticking and increase levels gradually as cuttings callus and root. 

Water requirements 

Misting should maintain a film of water on the leaves, but overmisting should be avoided.

Rooting 

Root media temperature should be maintained at 73-75° F. Callus formation should be visible by day seven. Gradually reduce the misting frequency as roots develop. 

PGRs 

An early PGR application can be beneficial to vigorous varieties at this stage to avoid stretching.

Finishing 

Begin to fertilize as soon as roots begin to form with a 100 ppm N, no-phosphorus formulation.

By day 15, roots should have expanded to the edge of the cell. Continue toning the crop by increasing air movement and light intensity. Misting should be greatly reduced during the day and stopped overnight. PGRs may be needed on vigorous varieties. 

ESTABLISHMENT 

If receiving rooted liners, unpack liners immediately upon receipt and transplant within 48 hours. If transplanting is delayed, fertilize liners every other day with 100-200 ppm N. Rinse foliage with clear water to avoid phosphorus damage and do not allow media to dry out, as this will increase the probability of future pythium infections. 

Nutrition 

Fertilize after transplanting with 200-250 ppm N to charge the growing media. Rinse leaves with clear water after fertilizing to avoid phosphorus damage. 

Lighting 

Light levels should be increased to 4,500 footcandles (19 mols/day) after transplant. Shading and/or misting should be used at higher light levels to avoid wilting. Full light is desirable once plants start rooting out and no longer wilt. 

Temperature 

Temperature after transplant should be maintained between 75-85° F during the day and 70-75° F at night. Once liners are well-established, temperatures can be reduced to 70° F (day) and 65° F (night). Cool temperatures will slow overall growth, while high temperatures can cause heat delay, leaf edge burn and foliage distortion. 

PGRs 

PGRs can be applied if no growth regulators were applied in propagation or to prevent lateral stretch. If needed, chlormequat at 500-1000 ppm may be used based on program needs. Always follow label directions. 

Pinching 

Ever-branching varieties can be produced without a pinch to achieve a unique plant habit unlike a traditional poinsettia. Lateral branching will occur naturally at the base of the plant while the main shoot will produce a showy bract on top. Mini bracts will grow along the main stem and along the lateral stems. 

Pinching should take place when roots reach the edge of the growing container, approximately 10-14 days after transplant or 4-5 weeks after direct sticking. In general, the number of nodes remaining should match the finish container size (i.e., 5-6 nodes for a 6-inch pot). Leaving too many nodes will encourage weak, horizontal growth and is not recommended. 

VEGETATIVE GROWTH 

Spacing pot-tight can encourage V-shaped habits on some cultivars, but is not needed on naturally V-shaped habits. Plants should be spaced apart once leaves begin to overlap.

Fertilizer is recommended at a constant feed of 100- 200 ppm N from a balanced formulation, including minor nutrients. Molybdenum and calcium are particularly important. Weekly calcium foliar sprays from calcium chloride are beneficial to encourage strong growth, prevent leaf edge burn and prevent bract edge burn. A small portion of the crop should be tested 3-4 days prior to spraying the entire crop. To increase stem elongation, increase phosphorus by approximately 10 ppm. 

Temperatures should be maintained between 68-78° F (days) and 65-70° F (nights). Temperatures can be manipulated to regulate growth. Positive DIF can be utilized to increase stem elongation. Negative DIF can be utilized to slow stem elongation. 

Height control is important to prevent internode stretch or promote stem elongation to reach desired height. There are programs available to assist with height tracking, such as OnTarget: Graphical Tracking. Decisions regarding cultural manipulations such as DIF, additional spacing, growing temperatures, etc. or the use of chemical PGRs may be made based on understanding the actual plant growth and estimated growth potential for the crop. It is important that PGRs are mixed and applied at appropriate rates and dates to avoid distortion of bract size or color development. 

Chemical PGRs can be applied during the vegetative growth stage to promote final plant height specifications. Sprays can cause significant bract regreening when applied just before and during early bract development. Bract regreening is much less likely to occur with drenches. Ensure thorough application and drench along with 200-250 ppm N from a 20-10-20 formulation. For each additional 1 ppm of GA4A7, 6-BA applied, 1-2 inches of additional stem elongation can be expected. 

FLOWER INITIATION 

Temperatures below 65° F in September encourage flower induction, while night temperatures above 70° F delay induction. Shading of crops may be utilized to create artificial short days and initiate flowering early. Crops should be shaded for a minimum of 12 hours to achieve a flower initiation response. Be aware of light pollution sources that can negatively affect flower induction. If light pollution is a problem, shading must continue until 25%- 50% flower color. 

All photos courtesy of Dümmen Orange.