Third-year heights, third-year root-collar diameters, and 3 yr volume growth of loblolly pine seedlings were examined in relation to a) root-collar diameter class at time of planting and b) herbaceous weed control. Treatments were a) no weed control and b) complete control for 2 yr. For both weed control treatments, means for third-year heights, groundline diameters, and volume growth were related positively to initial seedling diameter. The influence of initial seedling diameter on third-year diameters and heights did not differ among weed control treatments. However, the influence of initial diameter on volume growth did differ among weed control treatments. Thus, when using herbaceous weed control, additional gains in early volume growth can be realized by planting seedlings with large root-collar diameters.