Peat-based growing media in oil palm pre-nursery systems often presents limitations related to nutrient availability, acidity, and early seedling establishment, thereby requiring alternative organic amendments that are locally available, environmentally sustainable, and agronomically effective. Ludwigia octovalvis, commonly recognized as a wetland weed, has potential biomass value as an organic fertilizer; however, its influence to the vegetative growth of oil palm seedlings on peat media remains insufficiently examined. This study seeks to evaluate how different doses of Ludwigia octovalvis organic fertilizer influence the vegetative growth of oil palm seedlings grown in peat-based pre-nursery media. A quantitative experimental approach was applied using a fully randomized design consisting of five treatments: without Ludwigia octovalvis organic fertilizer, 25 g, 50 g, 75 g, and 100 g per polybag. The experiment involved 40 oil palm seedlings, with eight replications for each treatment, and was conducted for 12 weeks under controlled screen house conditions in Surakarta, Central Java, Indonesia. Data were collected through direct observation and measurement of plant height, number of leaves, stem diameter, root length, fresh weight, and dry weight. The data were analyzed using descriptive statistics, ANOVA, and Duncan’s multiple range test at a 5% significance level. The findings are expected to identify whether Ludwigia octovalvis organic fertilizer significantly improves vegetative growth and to determine the most effective application dose for peat-based pre-nursery cultivation. This study contributes to the development of weed biomass utilization as a sustainable organic input for early oil palm seedling production.