In order to investigate the effect of different planting dates in spring and also plant density on yield and some of morpho-physiological traits of garlic a split plot experiment was conducted based on randomised complete block design (RCBD) with three replications. Experimental treatments were three planting dates (March 5, March 25 and April 14) and four planting densities (20, 40, 60 and 80 plant. M−2). Based on results the interaction of experimental treatments on garlic yield, leaf weight, plant height, total chlorophyll and carotenoids was significant whereas for harvest index, number of produced cloves in plant, chlorophyll a and relative water content only the effects of planting date and plan density were significant. The highest garlic yield (921 g. m−2) observed in planting date of March 5 with density of 80 plants. M−2 but the lowest yield (317 g. m−2) obtained in the last planting date with the lowest plant density. The same results also observed for leaf weight. The highest amount of chlorophyll (2.52 mg. g FW−1) observed in planting date of March 25 with the density of 20 plants. M−2 but planting density of 80 plants. M−2 in the last planting date resulted to the lowest amount of total chlorophyll (2.07 mg. g FW−1). The highest harvest index was related to the first planning date and with delay in planting date, this index was reduced significantly. The lowest number of cloves per plant (3.64) was related to the last planting date. Increasing plant density also decreased the number of produced cloves by 14 percent. In terms of garlic yield, the best planting date in the studied region (with Mediterranean climate) was March 5th. Although increasing plant density resulted in higher yield but because of smaller size of produced bulbs, the marketable yield decreased.
