How do landscape architects use colour, form, texture, and line in plantings?

In landscape architecture, plants serve as primary design materials that are manipulated alongside elements like stone and wood to create functional and aesthetic outdoor spaces. Because plants are living, they are not static; they change through growth and seasonal cycles, requiring designers to account for these shifts when using the following elements:123

• Colour: Used to provide definition and interest, colour varies by hue, value, and tone. Designers consider how light and shadow play on foliage and flowers, and how bright colours can make spaces appear to advance while duller colours make them recede.4
• Form: Plants are categorized by their physical shapes—such as vertical, horizontal, round, or irregular—which can be further refined through horticultural techniques like topiary, espalier, or pollarding.53
• Texture: This refers to the size, shape, and arrangement of a plant's foliage and structure. Texture influences how a surface is perceived, whether it appears smooth or rough.34
• Line: Lines are created by the silhouettes of plants, the boundaries between different materials (like grass and paving), or the edges of shadows. They guide the viewer’s eye through a landscape, helping to define the composition and spatial experience.2