Since 1999 hybrid aspen plantations have been established on former agricultural lands for production of pulpwood as a practice of short rotation plantation forestry in boreal Estonia. During the early growth period the dimensions of the trees have been highly variable. The main objective of the study was to explain the high variability in early growth speed of hybrid aspens by differences in physicochemical soil properties. A network of 51 experimental plots was created to study growth–soil interactions in 5-year-old plantations at various sites. The mean height of the trees was 2.7 ± 0.02 m, mean diameter at breast height was 1.9 ± 0.02 cm and mean current year height increment was 0.7 ± 0.01 m. Mean foliar concentrations of main mineral nutrients were estimated as follows: N 2.15%, P 0.20%, K 0.76%. Trees have grown faster on Arenosols, Albeluvisols and Planosols. Growth intensity has been poor on Luvisols, Cambisols and Gleysols. While evaluating site quality based on soil texture and drainage condition, we found, that in general, hydromorphic soils have been less favourable. At a young age, hybrid aspen grew faster on automorphic soils with loamy sand and on semihydromorphic soils with loam, silt loam and sandy loam texture. The study of height increment in 5-year-old hybrid aspen plantations allows us to predict that the modest growth rate during the first years after planting could improve at an older age. Preliminary impact hierarchy of site properties, especially soil moisture condition, may change during later growth stages, when light competition in the canopy layer of the stand and nutrient competition between the tree roots in the soil will become more decisive for the growth performance of the trees.