Abstract Sustained-release fertilizer and two kinds of mulch treatments were tested to determine their effects on survival and growth of planted Chamaecyparis thyoides (Atlantic white cedar) on a sandy extremely nutrient-deficient site. Height, basal trunk diameter, dry weight, and concentrations of nitrogen (N), phosphorus (P), and potassium (K) were measured for each treatment. After two growing seasons, survival was very high in untreated controls (mean, 86%) and was not significantly increased by any treatment (significance was assessed at p = 0.05 throughout this work). Stem height and cross-sectional area doubled in unamended plots during the course of the study. Fresh mulch alone caused no additional increase in growth, compared with unamended plots. Decomposed mulch caused a slight but significant increase. Sustained-release fertilizer caused significant increases in height (threefold) and dry weight (approximately sixfold). Combined treatment with fertilizer and mulch gave significantly greater growth responses than did other treatments, increasing heights 4- to 5-fold, trunk cross-sectional areas 4-fold, and dry weights 11- to 21-fold over no-treatment controls. Tissue concentrations of N and P correlated with growth trends, with combinations of mulch and timed-release fertilizer providing the highest values. Though statistically different, the two mulch treatments were similar in their effects on tissue nutrient concentrations. When combined with fertilizer, undecomposed mulch stimulated increases in height and dry weight significantly more than did decomposed mulch. Thus, establishment of C. thyoides on low-nutrient sandy soils is improved by combined soil amendment with sustained-release nutrients and organic mulch.