Replacement of commercial peat media buy local composts would greatly improve transplant seedling production efficiency. The quality and effectiveness of substrate mushroom compost (SMS) was evaluated as a complete substitute for promix (PM) in the germination, growth and development of tomato seedling. Contrasting physicochemical properties were observed for the SMS and PM, both substrates falling outside the ideal media range for many properties. Germination percentage was > 95 % for both SMS fine (SMS F ) and PM treatments. The two SMS course (SMS C ) treatments showed significantly lower germination. For all growth parameters the fertilized SMS F treatment showed the greatest values at all sampling times. The non-significant difference between the fertilized PM and unfertilized SMS F treatments was notable. SMS treated seedlings were taller (32 %) and possessed a greater number of leaves (12 %) at 5 weeks after seeding (WAS) than PM seedlings at 6 WAS. SMS was shown to be a better media for tomato seedling production.