Window boxes have large areas for planting, which can give the impression of annuals in the ground-minus the turning of the dirt, the stooping and the stooping again to weed. They also put the action at eye level. Window boxes on a second story is a striking surprise. Sizing a window box appropriately is the toughest part. Plan carefully, so your boxes thrive.
I like window boxes to be sized generously in width. Sizing the box wider than the window puts the visual weight at the bottom, where it should be. A box narrower than the window makes the window look top heavy and oppressive-windows are large dark shapes during the day. �
Window boxes are not just for French and English cottage style homes. A sleek contemporary box can compliment the architecture of a modern home. They provide great mass and substance in the horizontal plane. They have the added attraction of views from inside, as well as the outside.
A very wide box invites planting tall annuals, even vines, which serve to frame the window. The large planting space allows you to showcase the relationship between a number of different plants. Boxes have the heart of a whole garden, in a smaller space.
Many ready made window boxes are sized more to be convenient to load into your car, than convenient for good plant growth. Undersized boxes are the devil to keep watered, once the plants have rooted in well. These boxes are 11″ wide and 16″ tall-plenty of room for a soil mass that will retain moisture evenly, and allow for root growth. A window box that is 8″ tall and 10″ long will need succulents, as they do not root deeply, and they are happy in dry soil.
Window boxes have no need to be fancy, especially if your idea of a good one is profuse and spilling over with flowers. Luxuriant-I like the word, and the look. These boxes are made from a simple iron grillwork, and lined with galvanized sheet metal liners. Wood boxes will last much longer, if they have sheet metal liners. Wood that is constantly wet deteriorates quickly.�
Wet soil is incredibly heavy; be sure the boxes are securely fastened to the wall. The weight issue is somewhat mitigated by the drainage material; I routinely fill the box at least half full with drainage material; bagged bark works well.
Not all boxes need to be attached to a wall. Boxes can be integrated into a pergola roof, or placed on top of a wall to good effect. Clear irrigation tubes can be run to them. This makes watering simple, as long as you experiment until you know how much time it will take to soak them. A plain sheet metal box will need reinforcement on the interior to prevent the metal walls from bowing out. I sometimes screw treated lumber to the inside to maintain a cleanly rectangular shape.
Window boxes are not just for sunny locations. The caladiums, dieffenbachia, and yellow coleus in this box light up a very shady spot. The trailing licorice is surprisingly tolerant of shade.�
A great window box is rhythmic. Decide if you want the height in the middle, or at the ends. A uniform height is a more contemporary look. The colors of nicotiana-terra cotta, and 2 shades of lime, set the stage for this box. All the supporting cast plants repeat color, or contrast in texture. A lime green variety of hops is growing on wires outside the shutters. Wispy small growing grasses are great in boxes, as they are neither upright nor trailing. If you are after a tall middle, plant the center first, then work to the edges. If you are fond of symmetry, reverse the order of right half on the left.
This box, tucked neatly between dark stained shutters, makes the flowers, and shutters the center of attention. This arrangement of a formal box and equally formal shutters, and green and white planting is elegant, but lively. �
These boxes, specially constructed to sit astride a narrow brick wall, say welcome in a very big way. What a happy improvement over the wall.