Culture Report: Petunia ColorRush Series
The ColorRush series of petunias was introduced for retail sales in 2017 and was highly noted for its big-time vigor and top garden performance. However, it launched with only a few colors (Pink and Blue).
For the 2020 retail season, growers can now offer new colors and novelties to their customers with the influx of Merlot Star, Purple, Watermelon Red, Pink Vein, and a phenomenal, crisp and clean White.
In addition to being an excellent choice for home gardeners to add color to their outdoor living space, ColorRush petunias are ideal for greenhouses that supply professional landscape companies. Each variety has blooming power that last all summer long, and they stand up to weather, heat and humidity like a champ.
Ball FloraPlant has trialed ColorRush across the country: Florida, North Carolina, Illinois, central Texas and California. Data was recorded about how it bounces back from rain quickly, thrives in extreme temperatures and blooms continuously. With that kind of garden success, customers will return again and again.
Across all its colors, ColorRush petunias have nicely matched habits, making production planning easier. Here are a few tips for growing the best-looking plants for your customers.
PROPAGATION
Choose a well-drained medium with an EC of 0.75 to 0.80 and a pH of 5.4 to 5.8. Stick cuttings within 12 to 24 hours of arrival. Cuttings can be stored overnight, if necessary, at 45 to 50° F. Soil temperature should be maintained at 68 to 73° F until roots are visible. Begin fertilization with 75- to 100-ppm nitrogen when roots become visible. Increase to 150- to 200-ppm nitrogen as roots develop. Once roots are visible, the media should be kept moderately wet and never saturated. This is critical to prevent iron deficiency and the associated chlorotic foliage that can develop.
Appropriate water management, air and light levels should eliminate the need for chemical PGRs. Avoid stretch by moving the crop to cooler air temperatures during the last weeks of propagation. No pinch in propagation is necessary.
GROWING ON TO FINISH
ColorRush Petunias should be ready for transplant three weeks after sticking. Use a well-drained, disease-free, soilless medium. Maintain a media pH of 5.4 to 5.8. Recommended temperature is 53 to 61° F nights and temperatures: 59 to 76° F days. ColorRush petunias should be grown under moderate light levels; 5,000 to 8,000 foot-candles is the ideal range. Low light levels promote stem stretch and reduced plant quality.
The medium should be allowed to dry between watering; however, periods of sustained wilting should be avoided. Petunias are susceptible to Botrytis and root diseases — avoid high humidity, constantly saturated media and wet foliage.
ColorRush petunias have a high feed requirement. Use constant feed with a balanced fertilizer at 225- to 300-ppm nitrogen with additional iron as needed. A full complement of minor elements should be provided to the plant. Regular leaching with clear water will help to reduce buildup of excess salts in media.
ColorRush petunias are free branching and do not require pinching. Pinching will delay flowering approximately three weeks.
Plants must be monitored regularly for early visual signs of upward pH drift (interveinal yellowing on youngest leaves). Regular soil pH tests are an excellent way to identify movements in pH before they create visual symptoms, which can be difficult to correct. Periodic application of acidic feed or drench applications of a chelated iron product can be used to maintain appropriate pH levels.
An effective method of lowering pH is a soil drench of iron sulfate. The foliage must be rinsed immediately after treatment, since the iron sulfate solution can result in phytotoxicity to flowers and foliage.
CONTROLLING GROWTH
Use high light levels and cool temperatures to control growth. To control growth and improve flowering and habit, growers can use one or more applications of B-Nine (1,500 to 2,500 ppm) starting seven to 14 days after transplant. Mature plants that are approaching shipping size can be drenched with Bonzi (1 to 4 ppm) to significantly slow vegetative growth while allowing flowering to continue. NOTE: Use of PGRs can delay flowering one to two weeks. Avoid spraying once flower buds appear. In general, more frequent applications of any growth regulator at a lower concentration will produce the best results.
NOTE FOR LANDSCAPERS
The newly introduced ColorRush colors will appeal to your landscaper customers. They’ll appreciate how they fill large beds and explode out of municipal containers and baskets. Since these customers will be interested in 4-inch or quart pot sizes, here are some tips to meet their needs:
An early Bonzi 5-ppm spray application in the liner stage, approximately eight days after stick, will effectively control early growth. To control finished growth in the 4-inch or quart pot, apply Bonzi 5-ppm soil drench approximately two weeks after transplant. Our trials found that this Bonzi drench was enough for the entire crop cycle and included a pinch at transplant.
Treatments above did not significantly reduce flowering compared to our control. Treatments above also did not significantly reduce growth habit in the landscape.
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