Populus deltoides is an important forest tree, with elite genotypes propagated mainly as unrooted dormant cuttings. Several areas where P. deltoides is planted periodically experience flooding episodes. The aims of this work were to analyze the early rooting capability and flooding tolerance of a P. deltoides full-sib family, and to identify growth, wood, and leaf traits correlating with flooding tolerance. We analyzed the early rooting capability of the parental genotypes and 30 clones from their F1 under greenhouse conditions. The rooting percentage of the cuttings ranged from 50 to 100%. There was a positive genetic correlation between shoot weight and root traits (number, biomass and total length). In a separate experiment, 2-month-old plants growing in pots from the same genotypes were subjected to two treatments: watered (control) and flooded for 35 days. Most genotypes showed an intermediate flooding tolerance with respect to the parental clones. Height, diameter, growth rate, biomass, plant leaf area, leaf number and leaf increase rate had a positive phenotypic correlation with flooding tolerance, while wood density did not. Height and diameter are traits recommended for selection because they correlate with flooding tolerance, are easy to measure, and have moderate to high narrow sense heritability.