Nowadays, greenkeeper's are under increasing pressure to provide near perfect playing conditions throughout the year in the face of greater player usage, wear and tighter environmental regulations. These demands result in stressed turfgrass plants, plants with reduced leaf area, limited photosynthetic capacity and increased susceptibility to disease infestation. Several new products such as biostimulants have been developed to help turfgrass managers to deal with these challenges. Manufacturer claims are that these products may supplement standard fertility programs by reducing mineral nutrient requirements, while improving stress tolerance. However, there is limited field-based evidence to support this. The objectives of this research were to determine the effect of applying seaweed extract on turfgrass growth and nutrition under a foliar fertilization programme on a golf green constructed to USGA specifications. Treatment plots were fertilized on a monthly basis using a foliar fertilization programme at standard, two-thirds and one-third nutrient rates in the summer of 2005. Liquid seaweed extract (Maxicrop) was applied on a bi-weekly basis at the recommended rate of 2mls per m-2 to each of the nutrient rates. Controls for each nutrient rate were included. A completely randomised design with three replications was used. Grass dry weight, tissue and soil macro nutrient concentrations and grass colour were measured on three dates. Leaf proline concentration was also measured. The application of seaweed extract increased grass colour on the first two measurement dates. Tissue N and K concentrations were increased on the first measurement date by the seaweed extract treatment. The biostimulant significantly reduced leaf proline concentration compared to the control at the end of the experiment.