Add a Little Glamour to Your Perennial Lineup

Jeremy Windemuller

Growers looking for a perennial with fantastic impulse appeal should consider Phlox paniculata Glamour Girl, hybridized by Walters Gardens, Inc. Her strongly fragrant, nearly fluorescent coral pink blossoms are irresistible. If you’re wary of growing phlox because of its notorious disease issues, take another look at this new cultivar that shows tremendous resistance to powdery mildew in production and garden use.

Pictured: Phlox Glamour Girl shows tremendous resistance to powdery mildew in production and in the garden. Growers looking for a shorter finish time should start with bare root plants in spring.

Potting and timing
Phlox Glamour Girl can be grown from 72-ct plugs or #1 Grade bare root. Growers looking for a shorter crop time should opt for bare root potted into trade 1-gal. containers in spring. They should finish in about 8 to 10 weeks when grown at 62 to 68F (16 to 20C) constant temp. 72-ct plugs should be potted in mid to late summer using one to two plugs per trade 1-gal. container or three plugs per 2-gal. pot. Bulking in summer takes approximately 10 to 12 weeks. Though this is not the fastest perennial to produce, it’s certainly worth the wait. Use a moist, well-drained growing media with a pH of 6 to 6.5.

Cultural recommendations
Fertility
Tall garden phlox are moderate to heavy feeders. Feed them with 75 to 150 ppm Nitrogen constant liquid feed at every watering or with 150 to 200 ppm Nitrogen as needed. Slow-release fertilizer should be applied at a rate of 1 to 1.25 lbs. per cubic yard of growing media. The recommended EC rate is 2.5 to 3.5 using the pour-through method.

Moisture
To avoid foliar disease issues, irrigate phlox early in the day to allow the foliage to dry before nightfall. Water plants thoroughly and allow the soil to dry slightly between waterings. Do not let the plants sit wet for a prolonged period.

Lighting
Tall garden phlox requires high light intensities to grow properly. When light levels are naturally low, you will need to supplement with a minimum of 3,000 foot candles of light. This will help to prevent the plants from stretching. As with all tall phlox, Glamour Girl is long-day obligate for flowering.

Temperature
Once plants are fully bulked in fall, they can be held over winter in a minimally heated greenhouse. Make sure they don’t sit too wet over the winter or crown and root rots may set in. Vernalization isn’t required for flowering, but a chilling period of six weeks at 35 to 45F (1 to 7C) greatly increases the quality of the finished plants.

Pests and diseases
Tall garden phlox can be subject to a number of pests and diseases. Prevention is key! Spacing plants properly, providing good airflow and watering in the morning will go a long way towards preventing issues with phlox. Allowing plants to dry slightly between waterings will help to prevent root and crown rots. At time of transplant, apply a broad spectrum fungicide drench on both bare root and plug material to prevent root and crown rot. 

Scout regularly for aphids, spider mites, thrips and whiteflies. Foliar diseases are less prevalent in Glamour Girl. In general, phlox can be prone to powdery mildew, Alternaria, Botrytis, Fusarium, Pythium, Phytopthera and Rhizoctonia. 

Finishing tips
Pinching and PGRs
When planted from bare root, Glamour Girl doesn’t need pinching since the plants are already well-branched. When starting from 72-ct plugs, one soft pinch is recommended 2 to 4 weeks after planting to encourage branching. If grown under proper high light conditions and adequately spaced, no PGRs are required for Glamour Girl. Tall varieties such as David may require PGRs. Use a spray application of a tank combination of 2,000 ppm daminozide plus 3 ppm uniconazole when plants are just under the desired height.

Forcing
Glamour Girl can be forced to bloom any time of year. Growers may wish to force plants that have been bulked up the summer prior to bloom in time for spring sales. This can be done by growing plants under 14-hour days at 65 to 70F (18 to 21C) constant temperature for 12 to 14 weeks. Supplemental lighting or night interruption lighting may be necessary to create the long days required for flowering. GT

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Jeremy Windemuller is a grower and trial manager for Walters Gardens, Inc. in Zeeland, Michigan.