Blue is a cool colour that is calming on the eye and makes objects seem to disappear into the distance, so use blues at the end of the garden if you want to make it look bigger.

In Summer, orange is a very in-your-face colour, so use it sparingly to make a striking impact or contrast.  But in autumn, it takes on a more mellow feel.
Yellow is a warm prime colour and associates well with the other prime colours, blue and red.
Hot colours always catch the eye and make objects feel closer

Opposite Colours on the colour wheel are orange & blue, purple & yellow and green & red.

These colours create some of the most striking combinations.

Adjacent Colours on the colour wheel  –  purple & blue

• Red & purple
• Orange & Red
• Yellow & orange
• Green & yellow
• Blue & green

Combining these colours creates a harmonious effect.  Can also add a third adjacent colour for increased impact.

Contrasting Colours are at equal distances on the colour wheel..

• Purple & green
• Blue & yellow
• Green & orange
• Red  & yellow
• Orange & purple
• Red & blue

Try plants with the above colours for a great contrast, or add another contrasting colour.e.g purple, green and orange