A sense of scale can help when designing a garden. Keep the relative sizes and distances of the plants in mind, because the way plants fit into their surroundings can have a dramatic effect on the viewer.
The goal should be to balance both the scale of the objects in your landscape to each other and to the viewer. There are no hard and fast rules here—you have to be the judge. Still, keep some notion of scale in your designing arsenal; subtle attention to it can pay big rewards later, when the garden matures.
Scale depends heavily on the viewing perspective, so try to think like a photographer: Determine a fixed viewing area (a porch, picture window, curbside) and view your garden site through a picture frame or a camera lens. Look for things that seem out of proportion e.g. large trees near a small house, small flowers hidden in a large bed, a huge tree too close to your viewing window, where all but the trunk is obscured. All of these things and more can disturb the ‘picture’.
A photographer will arrange things to capture a balanced, stimulating image. As a garden designer, you can do the same thing: you can choose plants and locations that bring the picture into proportion. When you plant beds, one option is to arrange taller plants in back, shorter ones in front, and step up the height gradually. This can add depth and clear sequence to a garden design. Alternatively, you can alternate plant heights to create peaks and valleys within your garden terrain. If there is a noticeable gap in the viewing window that demands attention, fill it with something. If you have a large plant or structure that dominates your site, try to draw attention away from it with clever visual distractions.
Of course, in most cases you will have constraints. You probably can’t move your house, and you may not want to remove that big tree growing next to the garage. You may get a good scale from one perspective but not from another. Sometimes your site leaves you with little room to work with. Our suggestion is to acknowledge what you can’t change, blend in some imagination, and work with the stuff you can change. Do your best and you won’t go wrong; any attention to proper scale is better than none at all.