Co-composting oil palm wastes, particularly the empty fruit bunch (EFB), frond and trunk with sewage sludge could be potentially converted into value added product. The objective of this study was to determine the best formulation using oil palm wastes and sewage sludge in producing a composted material to be used as a potting media in horticulture. Shredded oil palm wastes (EFB, frond and trunk) were mixed with sewage sludge in 3 different ratios (1:0, 3:1 and 4:1 ratio) using a polystyrene box and adjusted to 60% moisture content. At week 12, oil palm trunk with sewage sludge at 4:1 ratio was found to be the most optimum compost as potting media for ornamental plants because of its texture suitable for potting media, not stringent or stiff, had high nutrient contents (2.05 % N, 0.640 % P, 1.39 % K, 0.705 % Ca, 0.229% Mg), pH 6.2 and low C/N ratio, 19. Oil palm trunk + sewage sludge compost (OPTSC) was used as as a complete or partial substitute to peat and possible enhancing effect with Agroblend and Grofas chemical fertilizer in the production of potted chrysanthemum. The design used was a randomized complete block design (RCBD) with 9 treatments, replicated 5 times giving a total of 45 pots.