Gorgeous window boxes full of hydrangeas, and good looking shutters in Charleston, South Carolina. How to grow hydrangeas in pots/containers: http://www.hgtvgardens.com/hydrangeas/growing-hydrangeas-in-pots
Plastic Bottles instead of Pea Gravel Pea gravel and pebbles can weigh down window boxes. Empty water bottles are a lightweight option. Place rinsed bottles inside the planter and add soil on top of them. The space between the bottles will allow proper drainage without the extra weight.