Expert Tips for Successful Production of ‘Rainbow Sunset’ Potmum
May 28, 2019 
‘Rainbow Sunset’ potmum from Dümmen Orange is a fall flowering potmum that requires no disbudding or center budding. Rooting hormone is optional when directly sticking cuttings for propagation. Growers should pinch when the roots reach the sides and bottom of the pot, usually two to four weeks after sticking. One or two B-Nine applications will most likely be required after pinching to regulate plant height, but unlike other varieties, Rainbow Sunset does not fade because of late season B-Nine applications. A standard, well-draining growing mix works well, but be sure to keep the media moderately moist at all times. Humidity should remain between 70% to 85%, otherwise the risk of disease increases.
In January 2017, Meyers Fruit Farms and Greenhouses in Ontario, Canada, achieved first-time flowering for ‘Rainbow Sunset’ following an extensive commercial trial.
“When the variety flowered, we knew we had a candidate for our fall flowering program”, says Aron Hoff, Head Grower at Meyers Farms. “We were impressed with what we saw and knew our customers would be too.” Throughout the trial, strong, well-branched growth was observed, even under low-light winter conditions.
Potential diseases to watch out for include Botrytis, Pythium, Rhizoctonia, and powdery mildew. Common pests include aphids, thrips, spider mites, and mealy bugs. Beginning with a biological control program works well, then use any necessary chemicals when your shipping window approaches.
Adequately space plants to promote a strong, healthy crop with a rounded habit. Proper spacing is achieved when plants touch slightly once full grown, allowing proper airflow and decreasing chances of disease issues. To extend the shelf life for retail and the consumer, it is beneficial to switch to clear water when plants are at 30% color.
Hoff’s Recommendations for Growing Rainbow Sunset Potmum Successfully
Rainbow Sunset potmum has been a top performer in the fall market for Meyers Farms and will continue to be a large portion of the company’s fall potmum assortment.
• Propagation: A direct stick into 6.5-inch pots with four cuttings per pot through week 42 flowering, and five cuttings beyond week 42.
• Plant Growth Regulators: B-Nine is the preferred PGR with rates varying from 1,250 to 2,500 ppm.
• Lighting: Night lighting from 10:00 p.m. to 2:00 a.m. is required in the propagation phase, like all other potmum varieties.
• Pinching: Pinch when ready; when the roots are at the bottom of the pot, it is time to pinch.
• Growing media: Standard growing mix; well drained.
• Irrigation/fertilizer: Standard needs, but since this potmum has very dense foliage, it is probably best to go easy on the phosphorus.
• Planting/Scheduling: Using night lighting during propagation and blackout during flowering makes Rainbow Sunset easy to schedule. The 7.5-week response time noted by Dummen Orange is the best timing to bring this to market.
Learn more about Rainbow Sunset Potmum at DummenOrange.com.
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