Culture Notes Special Edition: Sun Spun Petunia

Ryan Hall

Petunias are one of the most established bedding plant classes. It holds its position as one of the top annual crops grown by volume rivaled only by geraniums and the relative newcomer calibrachoa.

You would think that with petunias’ long history, the genetic opportunities in this class would be tapped. Yet each year, we’re introduced to a bevy of new and exciting genetics that continue to wow us with improved performance and exciting, never-seen-before colors.

Colors are just one avenue pursued to maximize the potential of this class. Plant breeders have also focused heavily on improving habit and flowering, answering the challenge for earlier and earlier blooming genetics, and taming historically vigorous trailing habits. 

Called early flowering, mounded-type petunias, this new class has captured more than 20% of the petunia market. Early flowering, mounded petunias are a very grower-friendly product form. Their compact habits make them ideal for small container programs, such as quart and 2.5-qt. containers. Their mounded habit and bright colors create a beautiful product at the point of sale that’s covered in flowers. This type of petunia also makes them excellent mixed combo components. They blend perfectly with other spring annuals like verbena, calibrachoa and lobelia.

The Sun Spun series from Ball FloraPlant has all the key attributes you should expect from an early flowering, mounded petunia series, but Ball FloraPlant has taken this line a step further and focused on making sure Sun Spun is as uniform as possible. Series uniformity, early flowering and controlled habits give growers the full package of performance and predictability in an early flowering, mounded class. Sun Spun’s “Real Series” performance makes it ideal for high-density production in small pots, as well as space-efficient baskets. It’s also no mistake that Sun Spun is the primary foundation in Ball FloraPlant’s MixMasters multi-liner program, where it’s paired beautifully with Aztec Verbena, Hot Springs Lobelia and Cabaret Calibrachoa.

Crop time: Rooted liner to finish
Sun Spun Petunias are naturally compact and fast finishers. Sun Spun works great in small- to medium-size containers, such as 1-qt. and 2.5-qt. containers. Sun Spun will also grow well in 10- to 12-in. baskets, but growers should take note of the more upright, mounded habits in a basket—a notable shift away from the classic trailing petunias they might be used to.

Transplanting
Plant Sun Spun Petunia liners into a well-drained media. Peat-based and peat/perlite-based medias are an excellent option. Petunias aren’t as sensitive to pH as calibrachoa, but it’s always good to use a soil media with a pH between 5.5 to 5.8. Always start with pre-moistened soil and water in the liners after transplanting. Avoid letting the liners dry out during transplant. 

Pinching
Petunias have excellent branching naturally and generally won’t need or shouldn’t be pinched. Pinching should only be done as needed, especially if you’re dealing with stretched liners or soft plants that have overgrown in their container. Starting off with a high-quality liner and producing the crop cool and bright should avoid the need to pinch Sun Spun Petunias.

Temperatures
Another great advantage of petunias is their ability to be grown cool—a truly energy-efficient crop. Cool temperatures paired with bright light will create superior quality in this is class. Ideal temperatures for Sun Spun production are: Days—59 to 76F (15 to 24C), Nights—53 to 61F (11 to 16C).

Light levels & photoperiod
Provide petunias with the maximum light levels available. High light and longer days will give you the best overall habit and flowering. Ideal light levels range from 5,000 to 8,000 fc. Sun Spun has been bred to flower under shorter day conditions and will flower for most growers if daylength is above 11 hours.

Fertilizer & pH
Petunias are typically heavy feeders and do best with a feed rate of 225 to 300 ppm N. Nitrate-based fertilizers are best used to minimize soft vegetative growth that will adversely affect the overall finished quality of the plant.

Sun Spun has been bred to grow well under a range of pH conditions, but the best overall growth occurs between a pH of 5.5 to 5.8. Growers should avoid letting the pH rise too high, as this can cause iron deficiencies and yellow foliage. 

PGRs
The advantage of Sun Spun is its naturally compact growth, making it ideal for small containers and requiring little to no growth regulators. However, you can use PGRs as a tool for additional control if necessary.

B-Nine at a rate of 1,500 to 2,500 has proven to give effective control when applied two to three times early in the crop cycle. Bonzi can also provide effective control, but should be used sparingly in low rate drenches between 0.25 to 1.0 ppm.
 
Pests & diseases
Proper sanitation and IPM practices are the best way to avoid insect and disease problems with petunias. Growers should actively scout for common petunia pests, such as whitefly, thrips and leafminer, and treat accordingly. Growers should also regularly scout for diseases such as root rots and Tobacco Mosaic Virus.

Petunias continue to maintain their dominance as a key bedding plant gardeners can rely on. Innovations in both color and habit make this class more relevant than ever and Sun Spun Petunias from Ball FloraPlant answer the challenge for ever-better genetics the grower can rely on. GT

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Ryan Hall is a Product Manager for Ball FloraPlant.