Organic nursery production is facing problems related to peat substitution and sustainability of fertilization pattern allowed under organic rules. Three factorial greenhouse experiment was conducted to investigate the response of tomato seedling performance on different compost-based growing media. The factors include doses of compost (0%, 30% and 60% v/v), source of phosphorus (rock phosphate enriched compost or rock phosphate) and three levels of phosphorus (0g, 0.59g, and 1.18gP/kg). Different tomato seedling growth parameters were evaluated. Acceptable results were recorded till the higher compost doses (60%) tested. However, growth substrates with 30% compost showed the best seedling growth parameters regardless of the source and level of P enrichment. In addition growth substrates with 60% rock phosphate enriched compost produced better tomato seedlings than rock phosphate amended growth media with 60% compost
. Thus, at high compost doses, P in rock phosphate enriched compost become more available to tomato seedlings than rock phosphate.