I will go into this in future articles. Brick and terracotta go perfectly together, although this theme of terracotta will be a more dominant color scheme than gray will be. Cut stone is expensive, and can be slippery when wet, but it makes a wonderful paving, usually in tones of brown and gray. Rocks can sometimes be collected for free. If you use the same sort of rocks throughout your garden, the result will feel unified.
Paint is one of the easiest ways to use color to unite a garden.
You can paint treillage and garden furniture to match your house. Decking can also be used to unify a garden, when left to weather, it becomes a beautiful gray or it can be stained to match treillage, fences, gates and furniture in your garden. While a garden with flowers in a limited range of colors will feel unified, flowers are so fleeting that it is usually best to ignore them when focusing on unity. Lavender is an exception to this rule. Lavender flowers go with all other flowers except for the true blues.