How-To Make Easy Custom Size Window Box, Planter Box Liners - South House Designs
Liners
Amazon.com : HFHOME 24 inch Window Deck Rail Planter Including Coco Liner, 24" Dia Window Box Horse Trough with Coconut Coir Liners, Black Metal Hanging Flower Planter Basket for Indoor Outdoor Lawn -
48-Inch PVC Window Box Liner (8"H x 8"W)
Large Wrought Iron Window Boxes with Coco Liner | WindowGardensDirect