Spring Phenological Prediction R package spphpr version 1.1.5 Predicts the occurrence times (in day-of-year) of spring phenological events. Three methods, including the accumulated degree days (ADD) method, the accumulated days transferred to a standardized temperature (ADTS) method, and the accumulated developmental progress (ADP) method, were used. See Shi et al. (2017a) <doi:10.1016/j.agrformet.2017.04.001> and Shi et al. (2017b) <doi:10.1093/aesa/sax063> for details. Software Depends: R (>= 4.2.0) Peijian Shi <pjshi@njfu.edu.cn> Comprehensive R Archive Network (CRAN) Peijian Shi [aut, cre], Zhenghong Chen [aut], Jing Tan [aut], Brady K. Quinn [aut] GPL (>= 2) 2025-06-20 application/tgz https://CRAN.R-project.org/package=spphpr doi:10.32614/CRAN.package.spphpr