Transplanter which can avoid skips when planting, which skips may occur when seeds in a tray row fail to grow into seedlings. This is accomplished by picking up an entire row of seedlings from a tray, transferring the seedlings to a mechanism which eliminates gaps between seedlings, and then discharging the seedlings one at time to the ground with a desired spacing between the seedlings. A novel tray indexing mechanism is provided which can index trays of varying sizes. The planting mechanism has an air knife mounted adjacent transfer disks for straightening out the foliage as stems of seedlings before they are received by the planting disks, and the planting and transfer disks may be moved towards and away from each other for seedlings of differing heights.