Background: The Mentha spices can growth and adaptation with different climatology.

 Objective: This research was performed to investigate adaptation, suitable growth period, identification of suitable agronomy characters and identification of essential oil compounds of 2 ecotypes of water mint.

 Methods: This research was performed in Research Institute of Forest and Rangelands during 6 years in 1999 to 2004. Was conducted as a split plot at time by using of randomized complete block design (RCBD) with 3 replications. Main and sub factors were ecotype and year, respectively.

Results: There was difference significant between ecotypes on plant height, leaf long and total essential oil yield (α≤0.01) and lateral stem number, essential oil yield of flower and leaf yield (α≤0.05). There was significant difference between difference years on all traits at 0.01level. Investigation effect of year× ecotype showed that there was difference significant between plant heights (α ≤0.01), leaf long, essential oil percent of leaf and yield of flowering shoot (α≤0.05). There was difference significant between ectype2 with lateral stem number (29.44n/p), leaf yield (475579g/ha) and yield of essential oil (3314.5g/ha) than ecotype1 on lateral stem number (25.94n/p), leaf yield (460040g/ha) and yield of leaf essential oil (3224.2 g/ha). Mean comparison of years showed that highest and least flower yield with 48695 g/ha and 27733 g/ha belong to 2th and 6^th years, respectively.The highest leaf yield were 506723, 506225 and 549352 g/ha 1n first, second and 3th years. Main components were carvone with 50.58% and 76.03% in Ardabil and ghilan ecotypes, respectively.