The use of triticale (X Triticosecale Wittmack) has expanded greatly in recent years, in part to improve land stewardship by providing winter ground cover. Our objectives were to relate the DM yield and nutritive value of triticale forages grown in central Wisconsin with plant growth stage. Replicated 3.7- × 9.1-m plots of triticale were harvested at growth stages ranging from vegetative to soft-dough during spring/early summer of 2016 and 2017. Growth stages on each harvest date were quantified using a linear staging system suitable for use as a continuous, independent regression variable, where assessments during the trial ranged from 30 (vegetative) to 84 d (soft-dough). In 2016, the mean DM yield at boot stage (3,804 kg DM/ha) was only 30% of soft-dough (12,642 kg DM/ha). Although DM yields were reduced in 2017 due to spring flooding, the percentage of forage DM harvested at boot stage compared with soft-dough was similar (26.9%; 1,453 vs. 5,399 kg DM/ha). Regressions of DM yield (kg/ha) on growth stage for 2016 were explained by a cubic model (Y = 0.0663 x³ − 9.44 x² + 595 x − 9810; n = 30; R² = 0.985) compared with a simple linear response for 2017 (Y = 103 x − 3024; n = 24; R² = 0.934). Many nutritional characteristics, such as NDF, were affected by the juxtaposition and balance of 2 generally competing factors: (1) increased concentrations of structural plant fiber as plants matured; and (2) the accumulation of highly digestible carbohydrate during seed-head development. As such, the relationship between NDF and growth stage was best fitted to higher-ordered models for 2016 (Y = 0.0000369 x⁴ - 0.00886 x³ + 0.745 x² − 25.4 x + 342.5, n = 30; R² = 0.975) and 2017 (Y = −0.000570 x³ + 0.0828 x² − 3.14 x + 74.9, n = 24; R² = 0.950). Single-endpoint estimates of in vitro NDF digestibility after 24, 30, or 48-h incubations declined with plant maturity, and were closely related (R² = 0.906) to growth stage by linear or quadratic regression models that were similar across production years. Typical recommendations for harvesting triticale at boot stage to facilitate the planting of double-cropped corn are supported by the extensive 30-h in vitro disappearance of NDF at that growth stage, which comprised 63.1 ± 1.79 and 64.8 ± 7.39% of NDF for 2016 and 2017, respectively.