Extract from a paper by L.L. Bruner, G.J. Keever and C.H. Gilliam, Auburn University
The rather dramatic size of canna lilies makes them difficult to manage in nursery and retail settings. Canna lily species and cultivars are characterized by heights of up to five feet with leaves two feet in length and six inches in width. They bloom in mid- to late summer. Problems arise during container production due to their rapid and top-heavy growth habit. Pots blow over easily and shipping costs are increased. Plant growth regulators (PGRs) are effective in suppressing height in numerous species and may offer benefits in the production, shipping, and marketing of canna lilies. The objective of this study was to determine the effects of several rates of four PGRs on height and flowering of canna lily.
Canna lilies were divided and repotted in a substrate consisting of 7:1 pine bark to sand medium amended with 10.7 kilograms Polyon 22-4-14, 0.9 kilograms Micromax, and 3.0 kilograms limestone per cubic meter. Plants were placed in full sun with overhead irrigation. After the plants were measured the following PGRs were applied as foliar sprays: B-Nine, Bonzi, Cutless, and Pistill.
Results of this experiment show that vegetative and inflorescence height of canna lilies can be significantly reduced during production using Bonzi or Cutless. Height suppression was more persistent with Cutless than with Bonzi; however, plants treated with either PGR and transplanted into the landscape outgrew treatment effects within two months of planting.
Canna (Miniature Group) 'Froken', if subjected to the above chemicals we would never find it!