Competing vegetation limits the production of loblolly pine (Pinus taeda L.) plantations in the southeast U.S. The removal of competing vegetation throughout a rotation increases yield at final harvest, and can reinvigorate the growth of pines when site resources are deficient. Competing vegetation control treatments in operational settings are often applied in combination with fertilization or thinning. The effects of competing vegetation on pine growth during stand establishment are well known, but growth following mid-rotation treatment is less understood. Specifically, the growth of competing vegetation in response to treatments targeting pine productivity has not been studied in detail. Using a long-term study installed across the southeast U.S., the growth of pine plantations and their competing vegetation was assessed. Initially, an assessment of the growth trajectories, an analysis of the growth rates of different stand variables, and the relationship between pine and competing vegetation was conducted. Mid-rotation pine growth was found to be negatively impacted by competing vegetation, and the growth of competing vegetation was found to respond primarily to thinning and chemical herbicide treatment. Next, an analysis of the spatial distribution of competing vegetation looked at the relationship between spatial autocorrelation in relation to silvicultural treatment. Spatial autocorrelation was significant for both woody and herbaceous vegetation but did not differ among treatments. Models were then fitted for woody vegetation in terms of crown volume, and the percent groundcover of herbaceous vegetation using the same remeasurement data. Local and global parameterizations were considered and included the effect of silvicultural treatments. The local variable equations were able to accurately describe the growth of both vegetation groups when chemical herbicide treatment was accounted for in the model. Lastly, basal area growth was modeled for thinned stand and unthinned stands to include the effect of competing vegetation and silvicultural treatment. Basal area growth of thinned stands accounting for silvicultural treatment greatly improved the model fit when compared to a previously defined model for similar plantations. Ultimately, competing vegetation was found to be an important component of pine plantation growth and yield but further research is needed to fully develop methods for modeling its impact on plantation development.