Ensure Proper Lighting.
If you plan to lounge during the night when its darker and easier to relax after a busy work day then you need to ensure that your garden is lit in a way that is both aesthetically pleasing,creates the right kind of ambiance and is safe.
It is still important to light areas that may be a danger or tripping hazard, such as steps or around a garden pond.
The amount of light you’ll want in your garden depends very much on how much time you will be spending in it. If you want to eat and entertain on a regular occurrence it may be a good move to put up some overhead string lights that will illuminate the eating areas and create a party atmosphere.
For a more romantic setting some soft, low voltage lights or lamps strategically placed around the garden will create a warm glow but still allow you to look up at the stars without adding to the light pollution.
Different coloured lights can greatly add to any effect you are trying to create. Pretty coloured lights that reflect off any water feature you have in your garden will add a magical touch,while spot lights going upwards through the branch work of interesting trees will cast shadows for a more dramatic effect.
If you want to add to the natural glow cast from the stars and moonlight, consider blue-tinted lights. They work well around plants that produce white flowers at night, to create a ‘moon garden’—where the foliage reflects the natural light of the moon. Green lights mingled in with lower level foliage will help to create a soft and delicate ambience
Create an outdoor room.
As comforting as big expansive open spaces filled with flowers and greenery is, It is also a cozy and delightful experience to be in an enclosed intimate space of an urban garden. If you don't get much sunlight or don't have a lot of planting area, create visual interest with texture, hardscaping, fencing, gravel, etc. In the city, where space is often limited, the living space we create outside can add a sense of much more square footage. Use outdoor furniture and accessories as you would decorate a room in your home. Don't be afraid to bring a few throw pillows and a table linen from inside for a special meal when the weather allows.
Outdoor rugs are a great way to define a space and make the outdoors feel more special.
Create an enclosed sanctuary.
There's something so tranquil and peaceful about being surrounding and enveloped in a courtyard garden.
In the city we're often sandwiched tightly between our neighbors. Rather than letting this be a liability, use fencing, plantings, or the walls of the buildings on either side to create an enclosed sanctuary and secret garden feeling.
Employ simplicity and repetition.
Minimalist garden spaces are some of the greatest urban escapes at the tip of your fingers. If your space isn't conducive to growing lots of plants and flowers, go for the simplicity of monochromatic hard surfaces and sculptural furniture, as well as repeating one kind of plant multiple times for structured drama.
Create vignettes and sitting areas.
Regardless of how much space you have, creating small and intimate sitting areas are a must. This, after all, it's all about having an outdoor sanctuary in the city. If you don't have room for a dining table, go with comfy lounge furniture and a coffee table instead.
Rooftop gardens are one of the tougher garden design challenges. It's all about the view and the planters. Try using a structured repetition of the evergreen shrubs and the contrast between the greenery and the city.
For safety, unless your garden lightening is being installed by a professional electrician or lighting technician, always opt for LED lighting which is perfectly suited for outdoor use. Though LED lights are initially more costly than CFL's or Halogen lamps. LED lights gives you up to 20 years of service that is virtually maintenance free. They're normally IP66 rated which tells you that it's impervious to dust and is suitable for high pressure water hosing, and helps you save by lowering down your electricity bills.