There is no definitive list of landscape design principles, but there are many commonly referenced concepts that landscape designers engage with, including:
Balance – Symmetrical and formal, or asymmetrical and informal? Balance influences the style and atmosphere of a space, as well its ease of navigation.
Balance is influenced by the use of a regulating line – effectively a projected line originating from a prominent feature (a door, a tree, a large window). Regulating lines act like a spine for spaces to organize themselves around. Whether symmetrical or asymmetrical, layouts tend to feel more orderly, logical, and artful when responding to a regulating line.
Scale and Proportion – The size of features – both in an absolute sense and relative to their surroundings – affects their prominence. Put simply, big things feel grander and command more attention than small things.
Scale and proportion apply to all aspects of landscape design; the relationship between different plants, different hardscape features and structures, and people interacting with all these landscape features are all influenced by scale and proportion.
Enclosure – Related to scale, the degree of enclosure dramatically affects the character of a space.
Officially, when the height of a vertical edge exceeds ⅓ the horizontal length of that space, that space will feel enclosed, ideally in a comfortable, cozy way.
Put more plainly, spaces that have barriers on their edges, particularly tall, dense barriers, tend to feel smaller, more enclosed, and less connected to adjacent spaces. Conversely, spaces with wide, barrier-free edges tend to feel larger (by “borrowing space” from adjacent areas), more open, and more connected to the surrounding landscape.
Learning how to manipulate the sense of enclosure is a crucial skill for landscape designers.
Sight Lines and Focal Points – Focal points draw the eye to key moments in a design. Typically, best practices call for limiting the number of focal points – the fewer the focal points, the more impact each will have.
Sight lines can end at a focal point, but they can also extend between more generalized, non-focal features, like gathering spaces or planting areas. Clear sight lines strengthen a sense of connection between spaces, and contribute to a feeling of expansiveness in a design.
Enclosure is heavily influenced by sight lines. Spaces feel bigger when they have a clear view across an expanse. Spaces feel smaller when views are cut short by a tall hedge at the edge of a patio.
Rhythm + Emphasis – Rhythm refers to the repetition of alternating elements. Think of the drums: boom-bap-boom-bap.
Emphasis calls attention to a particular element or moment: boom-bap-boom-bap-CRASH!
Planting designs commonly use rhythm in height (tall-short-tall-short) and density (full-sparse-full-sparse) to draw the eye through a space and establish a sense of narrative. Accent features like plant containers, trees, or various decorative elements can similarly engage rhythm.
Emphasis injects drama and clarity into planting by calling attention to certain spaces or features. This actually helps to establish a rhythm by creating an alternating push and pull between emphasized and non-emphasized moments.
Unity – Designs are at their best when all their various components make sense together. A cohesive planting and material palette is crucial to a strong design.
Criteria for design unity must take client preferences into account – fans of cottage gardens see unity in highly diverse designs, while fans of minimalism prefer fewer variables.
Designs should always avoid being boring, but in general, a cohesive, unified feel can be achieved by limiting the different number of hardscape materials, plant species, and flower and foliage colors used in a design.