Dragonhead (Dracocephalum moldavica L.) is an annual, herbaceous, balm-scented and spicy medicinal plant of Lamiaceae family. An experiment was carried out during successive season to investigate the response of dragonhead to various plant sowing densities (10, 15, 20 and 40 cm) and iron nano-fertilizer (0, 1, 2 and 3 g lit-1 ) applications. Iron is a necessary element for plant's growth and plants deficiency or deactivation of iron show with chlorosis of their leaves. Results of ANOVA indicated there is not any significant interaction between nano-fertilizer and sowing density. Iron nano-fertilizer levels had a promoting influence on most of growth traits and accelerated essential oil accumulation. Similarly, wider plant spacing indicated the greatest effect on some growth components. Generally, the third rate of iron nano-fertilizer (2 g lit-1 ) combined with moderate distance between plants (15 cm) had a favorable effect on most of growth traits. The forth level of sowing density (40 cm) was the best in number of flowering branches, number of secondary branches and stem diameter traits while the second level of sowing density (15 cm) was the best in essential oil yield. Three levels of iron nano-fertilizer (0, 1 and 2 g lit-1 ) produced long height of first flowering branch while two levels of nano-fertilizer (1 and 3 g lit-1 ) had high number of secondary branches. The third level of iron nano-fertilizer (2 g lit- 1 ) had high values of total anthocyanins, chlorophyll b and total flavonoid traits. Two levels of iron nano-fertilizer (1 and 2 g lit-1 ) indicated high magnitudes of chlorophyll a, total chlorophyll, flavonoid 270 nm, flavonoid 300 nm and flavonoid 330 nm traits. It can be advised that medium distance (15 cm) and the second iron nano-fertilizer level (2 g lit-1 ), could be used for achieving high yield and essential oil performance.
