A continuous molding machine (10) for forming two chains (55) of soil plugs (50) for use in germinating seeds or otherwise growing plants. A continuous sheet of paper (22) is corrugated to conform to a series of mold elements (14) and a reaction mixture (32) of polymerizing agent and soil slurry is added over the paper to conform to the mold element shape. Another sheet of paper (38) is added over the top of the mixture (32) and the entire assembly is then passed under a series of pressure belts (42, 44, 46) during which time the mixture (32) is cured. The chain of soil plugs (50) which emerges from the pressure belts (42, 44, 46) is encased on both sides by paper (22, 38) and may be cut to provide a pair of separate soil plug chains (55).
