My home is a first floor flat with no garden, and my outdoor space is restricted to three square feet outside the back door at the top of the external steps that descend to the garden belonging to the ground floor flat. I have a small balcony at the front of the property which is all of 2 x 5 feet. 

However, it's amazing what you can grow in restricted spaces.  Below are the latest photos of my three square feet and back steps. We have had so much rain so we need some sunshine now to help the plants to flower and then the steps will be a mass of colour (blue, mauve and purple — my favourite colours and also colours that attract bees and other wildlife). 

The space is north facing so gets the late afternoon sun; however, it doesn't seem to affect the plants that are growing there. Unfortunately snails are an awful problem in London gardens so I am forever removing them from the pots.