(Aster) A blue addition to the Henry I series, Henry I Blue Aster is perfect for adding vibrant color to your garden in the fall. It features an abundance of small to medium-sized blue flowers and grows in a compact, mounding habit. Whether you have a spot in your garden, on your patio, or along your front walkway, this plant is the perfect addition to your fall decor. Plant in ground containers, hanging baskets, or window boxes. Henry I Blue grows best in full sun locations where it will get direct sunlight for 6 or more hours each day. Henry I is earlier to bloom than Henry II or III.