public class HerbGarden extends Garden {
   private static HerbGarden instance=new HerbGarden();
   private static boolean made = false; 

    private HerbGarden(){
    }

    public static HerbGarden getInstance(){
        if (!made) {
      made = true;
      return instance;//private constructor, only callable within
      }
    else
      return null; //return no further instances
    }

  // this is a simple factory
  // meaning contains factory methods
  public Plant getShade() { return new Plant("Mint"); }
  public Plant getCenter() { return new Plant("Rosemary"); }
  public Plant getBorder() { return new Plant("Thyme"); }
}