The forage potential of fodder beet (Beta vulgaris L.) grown under the Egyptian agricultural conditions has not been fully investigated. This study was carried out during two successive winter growing seasons (2014/2015 and 2015/2016) in Egypt and aimed to investigate the variations in yield and some quality attributes of fodder beet as affected by three sowing dates (15th September, 15th October and 15th November), three ages at harvest (120, 150, and 180 days after sowing - DAS), and boron application. Total, root, and shoot yields (t ha-1), as well as root and shoot dry matter contents (g kg-1) were evaluated. Fodder beet quality was judged in terms of the variations in the three fiber fractions (NDF, ADF, and ADL), in addition to the in vitro true digestibility (IVTD), and the NDF digestibility (NDFD). A pronounced response in most of the studied parameters to the different sowing dates and age at harvest was detected, while boron application had minimal influence on yield and quality of fodder beet. Early sowing (mid-Sept.) and late harvesting (180 DAS) resulted in the maximum fresh yield amounting to 170 ton ha-1, while a delay in sowing to mid-Nov. resulted in 53% reduction in fresh yield. The maximum dry matter content, on the other hand, was achieved with late sowing (mid-Nov.) and late harvesting (180 DAS). The role of boron in nutrient translocation from shoots to roots was clear in the significant decrease of the shoot dry matter content. However, no effect was observed for the root and shoot fresh yields. Harvesting at 180 DAS lead to the accumulation of the highest significant amount from the three tested fiber fractions (NDF, ADF and ADL). Regarding digestibility, both IVTD and NDFD values, declined with the increase in plant age at harvest. Results of the current study indicated that the fiber fractions of fodder beet roots and shoots were distinguishably lower than other forage crops. Furthermore, the high digestibility of 79% for IVTD and 60%for NDFD for fodder beet roots and comparable values for shoots, emphasize the excellent fiber quality of this crop. Records of the quality attributes of fodder beet, in the current study, in addition to its high yield, suggest that it can complement the high-protein berseem clover feed in critical periods of forage shortage and improve the nutritional value of the produced feed in the winter season in Egypt.