How are hedges shaped through trimming and topiary?

Hedges and shrubs are shaped through a combination of training and pruning, which are essential horticultural techniques used to direct plant growth.1

Training and Pruning Techniques

Training involves orienting a plant in space, often using supports to bend or fasten branches into a desired form. Pruning, the judicious cutting of plant parts, is used to contain size and improve appearance. Two primary pruning cuts are used to manage growth:1
* Heading back: Cutting the terminal portion of a branch to a bud. This stimulates lateral budbreak, resulting in a bushy, compact plant ideal for hedgerows.1
* Thinning out: The complete removal of a branch to a main trunk or lateral, which opens up the plant and encourages longer terminal growth.1

Topiary

Topiary is the specialized art of training living trees and shrubs into decorative or geometric shapes. While historically used to create elaborate figures like ships or animals, modern topiary often focuses on geometric forms to provide structure in formal gardens. Practitioners often use thick-leaved evergreens such as box, yew, or cypress, which respond well to the consistent shaping required to maintain these artificial forms.21