These data come from a roughly 4-year study on the growth response of a highly invasive woody plant to the damage induced by its biological control agent (an insect) and to soil fertilizer levels. The study design was an interrupted time series in which data were collected from plants for 2 years ("pre"), agents were introduced, and data collection continued for 2 years with sustained agent releases ("post"). Each month, stem tip counts and other measurements were collected from roughly 200 plants: 100 in each of two garden plots (IPRL and UF/IRREC). As plants grew larger (eventually to ~250 cm tall), data collection was spaced to roughly every 2 months and some replicates within each treatment were dropped. In addition to the "interruption" of introducing the agents, the other treatment was the addition of various concentrations of liquid fertilizer to the soil throughout the study. While there were no control plants that did not receive insects, each plant was followed over the course of the pre-post design experiment and Bayesian mixed modelling was used to interpret the effect of releasing the insect on how plant growth parameters changed over time and under different fertilizer levels. We have included raw data in .csv and .xlsx formats, one set for each garden plot as plots were analyzed separately. The Excel files have notes in the header column providing more information about each variable. However, not all variables were analyzed in the published study. The R code is also attached, which runs the Bayesian analyses for each plot and each response variable of interest in the published study. Raw data are also provided for soil and foliar nitrogen content. Soil nitrogen was analyzed at both plots, but foliar nitrogen was only analyzed at one of the plots (IPRL).