Four field experiments were carried out to assess the performance of black spruce (Picea mariana [Mill.] B.S.P.) outplants in relation to: weed control (i.e., with vs. without), stock type (i.e., bareroot vs. paperpot), and planting season (i.e., spring vs. summer). In one experiment, planting position (i.e., centre vs. side) within the mechanically site-prepared corridors was evaluated. In total, 1 800 seedlings were planted in each of the four experiments. These were then assessed after five and 11 growing seasons in the field. All experiments are located in northeastern Ontario in the Boreal Forest Region. Three of the four experiments are on upland, mixedwood, herb-rich sites; the fourth experiment is on a feathermoss-Sphagnum site type. Total height of black spruce outplants was not significantly improved by weed control 2 to 4 years after treatment. However, 8 to 10 years after release, weed control significantly improved black spruce height growth. Stem diameter was also greatly improved by weed control 2 to 4 and 8 to 10 years after treatment. The benefits of weed control increased over the experimental period and its effects on controlling deciduous trees and brushy plant species was still evident 8 to 10 years after treatment. The application of herbicides in narrow bands over the top of crop trees was shown to be a silviculturally effective alternative to conventional broadcast herbicide applications. Eleven growing seasons after outplanting, on three of the four experimental sites, bareroot stock remained significantly taller and exhib ited larger stem diameters than did papcrpot stock. However, the relative differences in size between the two stock types tended to decrease over the experimental period. In two of the four experimental plantings, current annual height increment of the bareroot stock was significantly greater than paperpot stock 11 growing seasons after outplanting. In general, the initial size advantage of the spring-planted compared to the summer-planted seedlings was maintained. Planting position within the site-prepared corridors was found to have a significant effect upon crop tree performance. Trees planted in the center of the 5- to 6-m-wide east-west oriented corridors were superior to those planted on either the north side or south side of the corridor. In addition, trees planted along the more exposed north side of the corridor were significantly larger than those planted along the more heavily shaded south side.