Cutting Type and Hormone Affect Vegetative Propagation of Phlox pulchra

Phlox pulchra Wherry is an herbaceous perennial endemic to Alabama that only occurs naturally in five counties: Autaga, Bibb, Butler, Shelby, and Tuscaloosa. To bring P. pulchra into production, this study examined stem cutting type and rooting hormones to determine if vegetative propagation is feasible for expansion of stock material. In September 2013, terminal or medial cutting sections were treated with a 1000ppm IBA (indole-3-butyric acid) and 500ppm NAA (1-napthaleneacetic acid) solution, 1000ppm IBA talc, or untreated (control). Cuttings were stuck in 1206 cell packs filled with 1:1 peat:perlite substrate and placed in a shaded greenhouse under intermittent mist.  The experiment was a completely randomized design with 6-packs as experimental units and individual cells as subsamples. After 6 weeks, number of roots greater than or equal to 5 mm, length of the three longest roots, and subjective root ratings (0-6) were recorded. Overall, 77% of terminal cuttings rooted, while only 11% of medial cuttings rooted. Terminal cuttings had higher number of roots, length of three longest roots, and root rating. For terminal cuttings, untreated cuttings and those treated with IBA/NAA solution had higher values for root number, length of second and third longest roots, and root rating.  Rooted cuttings were transplanted to trade gallons after measurements were taken and overwintered in a shade structure. Plants received daily irrigation and were protected when nighttime temperatures fell below 40 F. All but one cutting survived overwintering. With no difference between the control and IBA/NAA solution treatments, poorer performance of the IBA talc treatment, and no difference in overwintering survival, these results suggest application of the hormones tested is unnecessary to propagate terminal stem cuttings of P. pulchra taken in September.