Plant growth regulator effects on height and landscape performance of perennial bedding plants

Containerized production of perennial bedding plants is hampered by their v igorous growth rates and the lack of knowledge of their response to chemica l plant growth regulators. Six perennial bedding plant species were treated with foliar applications of 5000 ppm B-Nine WSG (every 2 weeks), a tank mi x of 5000 ppm B-Nine WSG and 1500 ppm Cycocel, or Sumagic at 0, 15, 30, 45, or 60 ppm. Vegetative plant height was measured at 3 and 5 weeks after tre atment (WAT), after which plants were planted in raised landscape beds to e valuate subsequent growth and quality. Five of the six species were respons ive to B-Nine, while the tank mix effectively reduced the height of four sp ecies (Salvia greggii, Heliotropium arborescens 'Fragrant Blue', Gaillardia grandiflora 'Burgundy' at 3 WAT only, and Perovskia atriplicifolia). These responses did not persist in the landscape. Four species, S. greggii, Salv ia leucantha, Gaura lindeheimeri 'Whirling Butterflies' and P. atriplicifol ia were excessively affected by 60 ppm Sumagic, with 45% height reductions. Carryover effects of Sumagic on plant height and performance in the landsc ape were observed at 4 weeks after planting (WAP) in S. greggii, G, lindehe imeri, and P. atriplicifolia, but only Gaura exhibited persistent growth re ductions at 8 WAP.