In order to study the effect of planting date and nitrogen fertilizer on yield and yield components of two varieties of spinach, an experimental in split-split plot design with three replication in spring, 2011 year on a farm in the city Friedan was performed. Main factors include planting date (20 and 30 April and 9 and 19 May) and nitrogen fertilizer (75 and 150 kg/ ha) as sub-factor and cultivars (Yazdabad and Vierflay) was considered as sub-sub factor. Traits were measured number of day to 50% flowering, days to maturity date, number of seeds per boll , 1000 seed weight(TSW), total plant weight and yield. There was a significant effect of planting date on all of the traits and nitrogen fertilizer levels had significant effect on the number of seed per boll and TSW. Effect of cultivar levels on all traits except days to maturity had significant effect. In addition, interaction effect between nitrogen and planting date had significant effect on all traits except days to 50% flowering and days to maturity. Interaction effect of planting date and cultivar on all traits had significant effect except days to 50% flowering and days to maturity. Interaction effect on planting date, cultivar, and nitrogen on all traits except days to 50% flowering had significant effect. The highest amount of TSW was belonging to fertilizer control level at 30 April and Vierflay cultivar. The highest number of days until 50% flowering (56 days), days to maturity equal to 92 days and the highest TSW, 12 grams and most of the total weight of the plant was 7 grams. In addition, the highest biomass yield was equal to 5 kilograms. Results showed that in Faridan region planting date of 30 April and consuming 75 kg/ha, nitrogen cultivar Yazdabad recommended for spinach planting.
