## 2 Materials and Methods
### Statistical Analysis  
Analysis of variance (one-way ANOVA), and [PERSON]'s Honest Significant Difference test (HSD) were performed to set up the significance of differences among cultivars and years of observations for the means (\(p\leq 0.05\)) obtained for frost damage, bud break (BBCH 07), leaf development (BBCH 11), the date of the start, and its abundance of flowering [46]. Each plant was treated as a repetition (Table 1) [47]. The STATISTICA 10 (StatSoft, Cracow, Poland) software was used. Additionally, correlation analyses were performed to examine:  
- The interconnections of frost damage, bud break (BBCH 07), leaf development (BBCH 11), the date of the start of flowering (BBCH 60 601), and its abundance. [PERSON]'s correlation coefficient (SPSS software, IBM Statistics) was used for all the cultivars separately. Figure 2: The abundance of flowering on a scale 0–5 in climber roses, where: (**a**) 0—plants fail to bloom; (**b**) 1—a few poor infloresences on shoot; (**c**) 2—c5 infloresences on 1 m of shoot, weak flowering; (**d**) 3—with 3–10 flowers in infloresences, average flowering; (**e**) 4—5 infloresences on 1 m of shoot, abundant and long flowering; (**f**) 5—abundant and long flowering, the infloresences densely placed on the plant. The association between average monthly temperature and frost damage, bud break (BBCH 07), leaf development (BBCH 11), the date of the start of flowering (BBCH 60 601), and its abundance for each month from October to April, and all months together for selected seasons (2005/2006, 2009/2010, 2015/2016) with a long and frosty autumn-winter-spring period (STATISTICA 10 software, StatSoft, Cracow, Poland). The correlations between minimum air temperature throughout the month and frost damage [46] (STATISTICA 10 software, StatSoft, Cracow, Poland). The correlation analysis was performed for each variety separately. Assessment of Weather Conditions in Polish Academy of Sciences Botanical Garden--Center for Biological Diversity Conservation in Powsin in View of Elements of Climate Change in Poland  
The Polish Academy of Sciences Botanical Garden--Center for Biological Diversity Conservation in Powsin is located on the outskirts of Warsaw (Poland, 52.6\({}^{\circ}\) N, 20.5 \({}^{\circ}\)E) in the Middle Vistula mesoregion. The area was separated from the Warsaw Plain by a high fluvial terrace at the border of a post-glacial plateau [48]. Warsaw, together with the Mazovia region, lies in USDA hardness zone 6B (minimal average temperatures \(-\)20.6 to \(-\)17.8 \({}^{\circ}\)C) [49]. The increase of temperature is clearly visible when observing the long-term average. For this purpose, data measured between 1973 and 2017 in the Warsaw-Okecie meteorological station, 10 km from PAS Botanical Garden, were provided. The linear trend with R-square values of linear regression [47] was conducted for average, maximal, and minimal monthly temperatures in the years 1973-2017, which expose the climate warming of the region; the data are presented in Figure 2a. The minimal, maximal, and average air temperature has risen by an estimated ca 1.5 \({}^{\circ}\)C over the past 44 years (Figure 3a). The climatic changes manifested by the increase of average air temperature were smaller in PAS Botanical Garden CBDC in Powsin (R\({}^{2}\) = 0.1028) (Figure 4). The increase of temperature is connected with a longer growing season in autumn [50]. As [PERSON] et al. [50] inform, in the years 2001-2009, the growing season in Poland was extended by eight days, wherein it was longer in the northwest (231-335) and shorter in the east (196-200). The growing season in the years 1981-2010 (216-220 days) was three days longer than in 1971-2000 in Warsaw, Poland [50]. Additionally, the date of the last spring frost noted for six meteorological stations in Poland was reported to be statistically significant earlier from 1.6 to 3.5 days per decade in the years 1961-2020, noted as consecutive days of the year. However, the last spring frost occurred 7-14 days earlier in the years 1991-2020 [51].