Do protocols for the intensive production of Coreopsis grandiflora affect its garden performance?

Scheduled production of ornamentals has facilitated the development of novel crop lines that can be sold in flower over an extended period, thereby maximising sales potential. Research activities have aided the development of protocols for these ‘forced’ crops, but little attention has been given to knowledge of how such protocols affect subsequent garden performance. The aim of this study therefore, was to investigate the influence of different production factors (cutting size, temperature, photoperiod and time of propagation) on flower induction both with respect to the main marketing stage, but also in terms of ‘after-sales’ performance. The short-lived herbaceous perennial Coreopsis grandiflora cv. Flying Saucers was used as a model subject. When exposed to five diurnal temperatures (14, 20, 24, 27 and 31 °C) and grown at four photoperiods (8, 11, 14 and 17 h), time to first open flower was optimal at 27 °C (42 days). Speed of flowering was aided by longer photoperiod (approximately 5 days earlier at 17 h than at 14 h). Greatest numbers of flowers produced overall though was associated with the 14 °C/14 h regime. Comparisons based on original cutting size demonstrated that large cuttings, rooted under long-day photoperiods produced plants with greater flower numbers than other cutting treatments. Once planted out, however, plants from all treatment combinations had similar floral performance (mean of 160 flowers per plant). Time of propagation/planting-out also had no overall effect on the numbers of flowers produced within the lifespan of the plant. It was concluded that conditions during production and planting time did not influence garden performance over the longer term.