Flowering Phenology of Shrub Roses as a Sensitive Indicator of Meteorological Variability in Central Europe

Climate change and warming affect the development cycle of ornamental plants and, thus, their quality and ornamental value. The study aimed to investigate the flowering phenology of 37 cultivars of shrub roses in response to meteorological conditions based on eight years of observations. Based on 14,800 field records, we grouped shrub rose cultivars according to their dominant flowering stage as a sensitive indicator of variability in weather conditions. We also selected the rose cultivars that would retain the highest ornamental value even at increasing temperatures. The total flowering duration of the cultivars ranged from 31 to 115 days (mean 90.4 days) and was significantly positively correlated with temperature. Meteorological conditions significantly influenced individual flowering stages (FS) and a trend of changes concerning the long-term gradient was observed: the increase in temperature extended FS10 and shortened FS25, FS50, and FS75 but did not affect FS100. If the warming trend continues, the abundant flowering of roses may be shortened considerably. Rose cultivars with the longest flowering period at FS10 abundance may adapt better to rising temperatures, and, therefore may be more useful in landscape planning and management.