In medicinal plants cultivation as well as other crops water deficiency in arid/semiarid areas is a critical challenge, but by understanding the process of its impact, and by applying appropriate management, its negative effects can be minimized. The competition for existing freshwater supplies will require a paradigmatic shift from maximizing productivity per unit of land area to maximizing productivity per unit of water consumed [1]. In this regard, the use of drip irrigation in irrigation of medicinal plants and the determination of the most suitable irrigation interval is a suitable method. Drip irrigation involves dripping water onto the soil at very low rates from a system of small diameter plastic pipes fitted with outlets called emitters or drippers. Drip irrigation method in comparison with other methods provides a very favourable high moisture level in the soil in which plants can flourish. Garlic is an important medicinal herb that is readily available everywhere. Garlic does indeed have scientifically-proven medicinal properties. It contains a substance called Allicin, which has anti-bacterial properties that are equivalent to a weak penicillin. Generally, garlic appears to have anti-bacterial and anti-viral properties. Here, an experiment was carried out as a randomized complete block design with -17 growing season. Garlic plants were irrigated by drip irrigation method. The studied traits included fresh and dry weight of bulbs, yield, and water use efficiency (WUE). Results indicated that the effect of irrigation treatments on fresh and dry weight of bulbs, diameter of bulbs, yield, and WUE was significant. With increasing irrigation interval from 6 to 12 days, these traits were decreased. Meanwhile, using 9 days irrigation interval as well as 6 days treatment significantly improved garlic production and WUE in compared to treatment of 12 days irrigation interval. This was further supported by a higher leaf area index and crop growth rate of such treat
