Trends in the Phenology of Climber Roses under Changing Climate Conditions in the Mazovia Lowland in Central Europe

Abstract

The genetic pool of valuable old ornamental cultivars and their in situ maintenance is threated by climate change. Meanwhile, ornamental plants like roses make up an important share of both gardens and urban green spaces, where they are particularly vulnerable to multi-stress growth conditions. The aim of this research was to evaluate the effect of changing climatic conditions on growth and flowering of 11 historic climber roses through long-term studies (2000–2017) conducted in Central Europe. The evaluation of plants consisted of assessment of frost damage and the timing of early phenological stages (starting of bud break, leaf unfolding), as well as gathering data on the beginning, fullness, and end of flowering and its abundance. Frost damage was not observed in any year only in ‘Mme Plantier’ and did not occur for any cultivar after the winter in the years 2007, 2008, and 2014. Only a little damage to one-year shoots was recorded after the winter in the years 2015–2017. Frost damage to ‘Alberic Barbier’, ‘Albertine’, ‘Chaplin’s Pink Climber’, ‘Orange Triumph clg’, and ‘Venusta Pendula’ led to pruning to ground level in every year excluding those listed above. Frost damage of once-blooming roses limited their flowering; however, the many-year datasets showed a trend for decreased frost damage and improved abundance of flowering, and these results can be interpreted as a response to the increase of average air temperature. The timing of bud breaking and leaf development in all climber roses was strictly correlated with average air temperature in the dormancy period. The reactions of climber roses to weather conditions confirmed the influence of climatic changes on ornamental crop plants in Central Europe, introducing the potential possibility for the wider application of climber roses, but without certainty of flowering every year.