As vermicomposts promote germination, growth, and improved plant yield, they have been promoted as a viable alternative to peat as container media components for the horticultural industry. The aim of this article was to compare the effects of two vermicomposts of animal origin, VCD, and of vegetable origin, VGF, as well as a cotton gin compost (CC), on a commercial peat-based (P) substrate on the growth of tomato seedlings (Lycopersicum esculentum cv. Momotaro) under greenhouse conditions. The results showed that the VCD treatment had the highest values of tomato seedling height, stem diameter, number of leaves per seedling, and total dry matter, followed by VGF, CC, and P treatments. These results support previous studies showing that both vermicomposts and compost can be used with very good results as alternative growth media to peat-based substrates. Nevertheless, the greatest plant growth values were obtained when applying the VCD and VGF vermicomposts followed by CC and P, possibly due to the higher mineral element contents of VCD, followed by VGF, CC, and P, respectively.