Where should you fit it?
If you want to fit window boxes on the outside of the balcony of an apartment, you should first check that there are no building or safety regulations that you need to observe. Remember that if there’s an accident with your window box you’ll be personally liable for damage or injury to third parties. As well as making sure your window box is mounted securely, you should also check that it can’t slide sideways out of the mounting brackets.
Potting compost and nutrition
When choosing your plants and window box, make sure there’s enough space for the roots. Use a substrate of clay pebbles, gravel or pot fragments. And of course you’ll need some potting compost to fill the window boxes. After a few months the top layer of potting compost will start to dry out and acidify, which means your plants won’t grow so well. You should then add some fresh potting compost and rearrange the plants. You can also buy different kinds of plant nutrition fluids or granules to keep your plants healthy and attractive. First check that you can easily water the plants, and that they are well drained.
What kind of brackets to use?
Mounting brackets for outdoor use need to be plastic-coated or galvanized to prevent rusting. Also make sure the container can’t move in the brackets. In many cases you’ll need to take care that the balcony fence won’t be damaged when you fit a window box. Which means you may not be allowed to drill holes!
DIY stores and garden centers have a wide range of special brackets for mounting window boxes.
Height of the window box
Are you planning to mount a window box in a high place? If so, make sure there’s still enough headroom so that the window box and plants don’t get in anyone’s way. For example that might be the case when you’re mounting a window box under your windowsill over the street or garden.
What kind of wall plug should I use?
If you’re mounting several window boxes try to fit them ‘in line’, both horizontally and vertically. That gives the best visual appearance. Mark out the first hole, place your spirit level horizontally and then mark out the next hole. Or in brickwork, drill the holes in the pointing (the gaps between the bricks). To mark out longer lengths, use a straight wooden plank to support the spirit level. In a stone wall you can use a universal 6 mm wall plug. For heavy window boxes you should use an 8 mm drill and corresponding wall plugs. Or for really heavy window boxes or containers, it’s best to use wall anchors.