In a method according to the invention, seedlings are planted using a planting device mounted to a vehicle boom. The device comprises two planting heads (1), an intermediate bar (2) connecting the planting heads, mounting means (3) for mounting the device to a vehicle, units (4, 5) for positioning of the planting heads, and planting means (6) arranged in the planting heads. The intermediate bar of the device is formed tiltable and length adjustable. The planting heads are attached to the ends of the intermediate bar by hinges. The structure of the device enables to adjust the mutual distance of the planting heads and to tilt them in relation to the intermediate bar. The planting heads (1) are so formed that they can be used for both backhoe and face excavation. The digging means are used for shaping and, if required, compacting the planting spot, after which the planting tube with its claw is lowered to an appropriate planting depth. The planting claw opens sufficient space for the seedling, and the seedling is fed from the seedling tray through the planting tube into the planting spot. Finally, the seedling is compacted on both sides by pads. The planting heads can be positioned according to the inclination of the terrain, so that the seedlings are placed vertically. The motion of the planting heads can be synchronized or they can take different positions independent of each other. When required, a suitable amount of fertilizer and/or pesticide is applied to the planting spot, by means of units located in connection with the seedling tube, for example.Plantation de semis par le biais dun dispositif de plantation monté sur une flèche de véhicule. Le dispositif comprend deux têtes de plantation (1), une barre intermédiaire (2) reliant les têtes, un système de montage (3) du dispositif sur un véhicule, des unités (4, 5) de positionnement des têtes, et un système de plantage (6) dans les têtes. La barre intermédiaire du dispositif est inclinable et réglable en longueur
