The effects of 13 growth retardants and inhibitors on the growth of container-grown seedlings of Pinuscontorta var. latifolia Engelm. and Piceaglauca (Moench) Voss were examined. Shoot and root growth was reduced to different extents by the various compounds, thus causing alterations in shoot/root ratios. The results are discussed with regard to the potential use of these chemicals for enhancing survival after outplanting or for use in held-over material. Ancymidol, Ethrel, Phosphon and Maintain caused decreases in the shoot/root ratio and may have potential for use in material to be planted out. CCC, RH531, Ethrel, and Mefluidide appear to have potential for use in held-over material.