THE INTERFERENCE of weeds with economic crops is a worldwide problem. The weeds suppress the growht of the crop plants and decrease their production. As the herbicides have several hazards, health and environment safe alternatives should be seeking. In this study, water extract of Trianthema portulacastrum (10g L^-1) was used to control the growth of weeds associating the plantations. Nine plots (each of 25m²) were prepared in a complete randomized design for different experimental treatments. The treatments were: a) Cultivated with maize without treatment (control), b) Irrigated with the extract (2 L/m²) once a day for 5 days (BC) before cultivation with maize, and c) Treated before cultivation and then irrigated with the extract until harvesting (IC) for two cropping seasons (April 2017 and April 2018). After treatment, the density of each weed species was calculated, maize growth parameters and grain nutrient contents were determined. The results showed that the associated weeds were declined to 54.1%, 52.8% in BC and 75.7%, 83.3% in IC during the first and second growth seasons, respectively. Plant height, number of leaves, leaf area, ear weight, number and weight of grains, grain yield and harvest index, the nutritive value of the grains (carbohydrates, proteins, fats and minerals), and soil parameters (organic matter and NPK) of Maize plants were increased significantly in the treated sites during both seasons. During the second crop season the number and the type of weed individuals were more declined than the first crop season as a result of treatment with water extract of T. portulacastrum. On the other hand the growth of maize increased during the second crop season as a result of treatment with water extract of T. portulacastrum. Our study obviously showed that the water extract of T. portulacastrum can be a potential bio-fertilizer and used to control weeds.