The use of biostimulants, which either feed indigenous microbial populations or add microorganisms to existing soils, is starting to gain popularity. Increasing the activity of benign soil microbes-especially in relatively sterile sand-constructed rootzones is of great importance because they may help to increase plant nutrient uptake and stress tolerance. The objectives of this research were to study the effect of applying a seaweed extract and a microbial inoculant on turfgrass growth, and nutrition. In a glasshouse experiment, rose pots measuring 15cm x 18cm (3L) were filled with a rootzone mixture to USGA specifications. The pots were divided into ten separate treatments.  Five treatments received two-thirds and five treatments received one-third of a recommended nutrient package. Separate treatments of bentonite clay carrier at the recommended rate of 12.5 gm.m^-2,  seaweed extract at the recommended rate of 50 gm.m^-2 and microbial inoculant (bacteria and fungi) at the recommended rate of 25 gm.m^-2 were applied to both nutrient rates. An additional treatment containing a mixture of the seaweed extract and microbial inoculant at their respective recommended rates was applied to each nutrient rate. Control treatments were used which only received two-thirds and one-third nutrient rates. Grass weights, tissue N, P, K, Fe, and Mg concentrations and rootzone N, P, and K concentrations were measured on a monthly basis for three months. Grass colour was measured at the end of the experiment. The application of the seaweed extract/microbial inoculant, and the microbial inoculant treatments increased grass growth. Tissue N concentrations were significantly increased by the seaweed extract treatment on two measurement dates. Tissue K was increased on two measurement dates by the microbial inoculant treatment. The seaweed extract/microbial inoculant treatment significantly increased grass colour compared to the control.