Two field trials were conducted at Sakha Agricultural Research Station (Kafr El-Sheikh) Governorate in two successive seasons; 1995/ 1996 and 1996/1997 to find out the effect of fertilization and harvesting date on growth traits and chemical constituents of sugar beet plants. Sugar beet variety viz. Pleno was sown during the first week of October in both seasons. The prsented work included 24 treatments which were the combinations between two Farm Yard Manur " FYM " (with and without FYM application), three mineral N doses (without application (control) 45 kg N/fed and 90 kg N/fed) were applied as Urea 46 % N in two equal doses where the first was added after thinning 45 days from sowing and the second one was added 21 days later, two application date of Phosphours fertilizer (with land preparaion (WLP) were applied as calcium super phosphate at 15 kg/fed (15 % P205).and band in rows at sowing (WS) and two harvesting dates (After 180 days from sowing and after 210 days from sowing). Data indicated that * Root fresh weight and dry matter percentage were positively increased by delaying harvest date up to 210 days from sowing. * Adding FYM increased the values of root fresh weight/plant in the two growing seasons and increased dry matter weight percentage in the first growing seasn only. * Application of Phosphours fertilizer with land preparation (WLP) statistically increased root fresh weight in the two growing seasons and root dry weight in the first season only. * Prolonged growing period from 180 to 210 days attained an obvious increase in root yield amounted to 9 and 13.2 %. Increasing N levels up to 90 kg N/fed gradually and significantly increased yield. * Traditional application of Phosphours fertilizer with land preparation produced higher root yield. * The increment in the values of sucroseas a result of FYM application was significant Increasding N fertilizer over 45 kg N/fed declined the values of TSS and sucrose %.* Delaying harvest from 180 to 210 days with application of FYM attained noticeable increase in juice purity % and sugar yield. * Both juice purity and sugar yield were significantly and positively increased by increasing the applied doses of N. * Application of Phosphours with land preparation produced higher values in respect to juice purity and sugar yield in both growing seasons