Plant nutrients in proper proportion keep the plant healthy and it is less susceptible to the pests. The nutrient analysis by invasive and non invasive methods has their own advantages and disadvantages. Traditional methods are time consuming where as non invasive methods have proved its importance in recent years. This paper proposes method using color image analysis for estimation of nitrogen for grapes. The function used to estimate shows significant correlation and gives the coefficient of determination of 0.89 with mean square error of 0.08935. The proposed method has advantage of time and cost effectiveness compared to conventional methods.