The present study was carried out during 2017/2018 and 2018/2019 seasons at Desert Agricultural Research Station, Toshka, Aswan governorate, Egypt to find out the optimum harvesting age (165, 180, 195, and 210 days) for five multi-germ sugar beet varieties namely Oscar, poly, Athospoly, Sarah, Ravel and Friancesca. Addition to study the effect of post-harvest treatments and storage period on quality characteristics of tested sugar beet varieties. The results showed that the Ravel variety with an age of 195 days recorded the highest increase values of sucrose (20.39 and 19.70 %) as well as lowest decrease values with the age of 210 days (18.39 and 17.07%) during two seasons, respectively. Delaying the harvest age of sugar beet from 165 up to 195 and 210 days caused the increase in TSS % of sugar beet juice. Francesca variety produced the highest values of sugar beet juice TSS (22.75 and 22.45 %) in both seasons. Treatment by 1% Ca (OH)₂ recorded the higher value of sucrose content during storage (16.84 and 17.85%) in both seasons. Ravel variety surpassed the other varieties in beet quality (88.84 and 84.78%) and juice purity (94.35 and 92.61%) while, the Oscar poly variety had the lowest mean values (81.71and 80.05%) and (91.10 and 89.88%) at different harvest ages in the two seasons, respectively. The lowest value of sucrose loss in molasses was obtained from Ravel and Francesca than the other varieties by (1.56 and 1.84%) whereas the highest loss value was obtained from Oscar poly variety by (2.10 and 2.21%) at different harvest ages in the 1^st and 2^nd seasons, respectively.