Interest in chemical modification of root systems of container-grown trees has increased in recent years with more widespread recognition of implications of root system architecture of container-grown trees on subsequent landscape performance. Initial research on Cu-based latex materials for application to interior container surfaces to avoid circled, matted, and kinked roots at container wall: media interfaces began with small forest tree liners in the late 1970s and early 1980s. Transfer of this technology to horticultural crops followed from the mid-1980s to the present. Testing has spread to a wide range of temperate and tropical landscape trees, shrubs, herbaceous annuals and perennials, interior foliage plants, and vegetable transplants. Inhibition of root elongation after contact with treated container surfaces is via a mild Cu toxicity, frequently resulting in a stimulation of lateral root proliferation proximal to the inhibited root tip, but responses vary with species, cultivar, media composition and pH, and Cu concentration and formulation. Early reports on root architecture effects were predominantly qualitative in nature. Quantitative studies on root architecture within treated containers have been less consistent in responses among species. Improvements in root regeneration, shoot growth, and water relations during post-transplant field establishment of trees grown in Cu-treated vs. non-treated containers have been documented for several species. Ecological (Cu leaching potential), technological (new applications), and economic (profitability) questions have arisen with increased use and availability of Cu-based container treatments and will be discussed.