Lavandula stricta Delile is a native species of Iran growing in southern Iran. Polyploidy induction using mutagenic chemicals such as colchicine is one of the breeding methods of medicinal plants, which has potential to produce the crop purposefully. To evaluate the feasibility of polyploidy induction in L. stricta, a factorial experiment in a completely randomized design with two treatments including five concentrations of colchicine (0, 0. 05, 0. 1, 0. 2, 0. 4 %) as a gel on the end plant meristem and four times (8, 16, 24 and 48 hours) with three replications and 20 experimental units were performed under greenhouse conditions. To observe the effect of colchicine on morphological and biochemical characteristics at the flowering stage, the height of aerial parts, number of main leaves (leaves on the main stem), number of sub leaves (leaves on sub-branches), number of internodes on main stems, number of lateral stems, spike length on the main panicle, number of spikes, number of flowers per panicle, fresh and dry weight of aerial parts, fresh and dry weight of roots, root length, leaf area, internode length, total phenol content, total flavonoids content, antioxidant activity, total sugar content and chlorophyll quality were measured. The results of the analysis of variance showed that the studied treatments had a significant effect on all traits except the number of main leaves, the number of internodes on main stems, and root length. The means comparison showed that with increasing the concentration and period of colchicine application, height of aerial parts, internode length, the number of flowers per panicle, and total sugar content decreased and spike length on the main panicle and total phenol content increased. Based on the results of flow cytometric analysis, the mean genome size was 0. 73 pg in plants treated with colchicine at a concentration of 0. 4% for 48 hours, while the mean genome size in the control plants was 0. 55 pg. Plants in other treatments showed a mean genome size of 0. 57. In general, the results of this experiment showed a positive response of L. stricta to colchicine for the induction of polyploidy and the possibility of using this method in the future breeding of this plant.