Printing a rectangle with a linear gradient as fill does only use the first color of the gradient to fill the complete rectangle with. Here is a test case:

{code}
public class PrintGradientTest extends Application {
  @Override
  public void start(Stage primaryStage) throws Exception {
    Stop[] stops = new Stop[]{new Stop(0, Color.BLUE), new Stop(1, Color.WHITE)};
    Paint gradient = new LinearGradient(0, 0, 0, 1, true, CycleMethod.NO_CYCLE, stops);

    Rectangle rect = new Rectangle(100, 200);
    rect.setFill(gradient);

    Group root = new Group(rect);
    primaryStage.setScene(new Scene(root));
    primaryStage.show();

    PrinterJob job = PrinterJob.createPrinterJob();
    if (job.showPrintDialog(primaryStage)) {
      boolean success = job.printPage(root);
      if (success) {
        job.endJob();
      }
    }
  }
}
{code}