Window boxes were once much more popular than they have been up to recently. But I am glad to see that they are making a come back. You can get so much pleasure from a window box that it is really surprising that everyone does not have several. There are so many different types of flowers now that have special strains developed specially to be grown in this type of environment. Anything that does well in one of those baskets that people seem to prefer these days, will do well in a window box also.
The colour and fragrance that they bring within easy reach of even the most casual gardener is such a recommendation without anything I have to say on it.
If you are not handy with a hammer, your local garden centre will no doubt have a good supply in various shapes, sizes and materials. Being old fashioned I prefer the wooden ones, but there are some very nice ones with metalwork and cheaper ones of plastic that will do a fine job. Of course you will see very little of them when the flowers are in full bloom.
All you need is a solid box that fits your window sill and that can be securely attached to it. Make sure that the sill can take the weight of a window box before you do anything else. You may need to get a professional to do some maintenance before you attach your box. There is quite a weight in them when they are filled with soil or potting compost etc. and watered. If you are inclined to fill your window box first and then attach is (not recommended) then you will need help to raise it and attach it to the window sill.
If you are going to make your own window box out of wood, I would recommend Cedar for it抯 natural resistance to rot and Oak. These are expensive woods compared to other lesser woods but a window box made from these woods will outlast most others even if untreated. The wood should be about one inch thick. (250mm) You can paint your window box but I never do because I like the wood finish and it suits the look of my house. But, you know your own house and should decide for yourself what look you need your window box to match.
Before use paint the inside of the window box with a wood preservative like Cuprinol or whatever the local garden centre recommends. Avoid Creosote. It is poisonous and kills plants. Not what you want in a window box.
Cover the bottom of the box with a layer of gravel to assist with drainage. You do not want water to collect at the bottom of the window box, even though it is covered with gravel, so make sure that has plenty of drainage holes in the bottom. Fill the box with suitable potting compost or whatever mixture the local garden centre recommends. You will get use to me saying this if you read more of my articles on this site. I always prefer to send you to a local supplier for this type of thing as brands and conditions vary widely around the world and it may confuse people if I was to recommend a particular item for your window box.
I will recommend flowers that I think are suitable for window boxes and they are ones that I use myself. They are, Lobelias, Petunias, Antirrhinum, Chrysanthemums, Marigolds and lastly Nasturtiums which seem to find and lose favour every couple of years. For scent I would also use Fragrant Stocks. There are trailing and dwarfed varieties that are very suitable for window boxes and hanging baskets.
If the weather is likely to get stormy I would recommend that you remove the window box until the bad weather has passed. The wind can do all kinds of damage to your flowers and even uproot them and blow them clean out of the window box.
One more thing. If you do decide to paint or use a wood treatment of some sort on the box, make sure that is dry and weatherproof before you put the window box on the window sill. It just looks so bad and can be difficult to deal with if it runs down the wall next time it rains.
The main thing is have fun with it. Just imaging walking into the kitchen on a summer morning and seeing the flowers in your window box at the kitchen window and taking a deep breath of the flowers?perfume when you open the window. Enjoy the flowers and the fragrance and it will brighten up your day. Your window box will make your day.