The wider the sill the better, as you'll be able to get bigger containers onto it. And if it catches the rain as well, that's even better - it'll save on watering later. Don't be too ambitious ...

But if you've found mould settling near your windows, you'll need to know how to clean mould from window sills to get them looking their best again. You might already know how to get rid of mould ...

Read these expert tips from the founder of Window Fleur on how to make your own garden window box. You’re now subscribed to all our newsletters. You can manage your subscriptions at any time ...