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.
Find Northcote Pottery 600mm Graphite Villa Plastic Window Box at Bunnings Warehouse. Visit your local store for the widest range of garden products.