I have some window boxes that I have my herbs in - long rectangle planters. Instead of actually planting the plants inside of them, I used pots that fit inside of the planters - one for each plant, 3 per box.

The problem is, I can't find any good brackets to hold them in place. Either they are too thin, and won't hold up the weight, or they don't have anything to keep it from being knocked over. (I have cats!)

The only things I can think of to do is to either somehow use rope tied around them to keep em from being knocked over, or I could just nail the boxes directly to the balcony, since the plants aren't directly planted in them anyways.

Does either of those sound like a good idea? Does anyone have any other ideas?