Colocynth is one of the major medicinal plants that naturally grows in deserts of Middle East and North Africa. Extending cultivation of this species is useful for sand dune fixation and for making incomes for the needy inhabitants. Despite of numerous studies on seed germination, there are still debates on best method of seed dormancy breaking for colocynth. Moreover, seed morphology, phonological stages, and habitat conditions of this species are not fully studied. In a flat plain of Gonabad, located at the edge Lut desert, we established line transects of 200 m and plots of 4×4 m, where vegetation parameters, phenology, and soil characteristics of Colocynth habitats were studied. Soil of study area was classified as slight alkaline, where pH varied between 7-7.5 in open and 8-8.11 under the canopy of colocynth. Two weeks pre-chilling at 5°C and day/night temperature range from 25-40°C significantly increased seed germination. In the study area colocynth was detected as a perennial herb with long and ligneous roots (>120 cm depth). Its vegetative growth starts at mid-May, seed ripening and shedding occur in October and November respectively. Average fruit volume was 2.62 m3 and seed number counted in each fruit varied between 250 to 420 by the length of 4 to 7 mm and 2-4 mm width. Bigger size fruits contained highest seed number, hence the full maturity stage is best harvesting time in terms of both economic value and seed viability.

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