A soil heater assembly (SHA) utilizes for example, two or more, 5 ft by 10 ft heating sections rigidly bolted together. Each section contains three NICHROME heating elements encased in ceramic beads which are floatingly pinned to a 4-inch thick ceramic fiber insulation encased in NEXTEL cloth. The heating elements run across the entire length and width of the SHA, spaced approximately three inches apart. The heating sections are pinned to their respective 5 ft by 10 ft stainless steel support frame, which is made out of structural angles and flat bars, with pins running through the four-inch ceramic fiber insulation. Since the insulation is somewhat compressible and the pins are slideable therethrough, i.e. not fixed, the heater elements can move or "float" vertically to accommodate surface irregularities of the soil. Both heating sections and support frames are then positioned side-by-side on the ground, bolted together, and covered by another four inches of fiber insulation. All of the insulation packages are surrounded by NEXTEL or a silica-based cloth for ease of handling and retaining their integrity. The entire assembly may be lifted by a crane and moved to another site, or it may be fitted with wheels and towed.