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.
Build a window box planter in 5 easy steps! Add curb appeal and improve your home exterior with a beautiful window box and some greenery and flowers. Step by step from construction2style on Remodelaholic.com
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