The chrysanthemum [Dendranthema x grandiflorum (Ramat) Kitamura cv. Polaris White] is one of most widely cultivated ornamental crops in Mexico. Its nutrient requirements in hydroponics are nevertheless unknown. This lack of knowledge limits the use of high plant density. Therefore, the effect of the osmotic pressure of the nutrient solution (0.018, 0.027, 0.036 and 0.045 MPa) on the growth and flowering of chrysanthemum was evaluated in Texcoco, in the state of Mexico using a hydroponics system of subirrigation in pots containing eight plants, which is equivalent to a density of 156.6 plants m-2, managed at one stem per plant and one flower per stem. The most notable growth and flower quality was obtained with 0.036 and 0.045 MPa osmotic pressure of the nutrient solution (plant height: 110 to 115 cm; stem diameter: 0.6 to 0.63 cm; internodes per plant: 33; leaf area: 730 to 790 cm2; inflorescence diameter: 11.4 cm; diameter of the central yellow coloration of inflorescence: 6.5 cm with 0.036 MPa; intensity of coloration and vase life period: 7.3 and 17 days, respectively, both with 0.045 MPa). Transplant to cutting time was diminished as the osmotic pressure of the nutrient solution increased (90 and 84 days with 0.036 and 0.045 MPa, respectively).

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