Varied lint yield responses have been documented across the cotton belt with the use of the MicroFlo System consisting of PGR-IV and mepiquat chloride (MC) applications. South Carolina has some distinct weather patterns that make it unique to other southeastern states, but no replicated trials evaluating PGR-IV have been conducted in the state. Therefore, we compared the System to a standard MC treatment and an untreated control at four replicated locations plus two non-replicated locations. Early-season growth was enhanced by the System, as expressed in shoot dry weight and node of first fruiting branch. Plant height was lower for the System treatment, although the response was likely due to the MC included in the System treatment. The System treatment produced more fruiting sites per plant, although total bolls per plant were not affected. Boll size was larger for System-treated plants and was explained by higher seed weight per boll, rather than by a lint increase. Lint yield was not influenced by the System, although a consistent, numerical increase was detected for the System treatment at all four replicated locations. Fiber strength and trash content was increased for System-treated plants.