Enhancing ecosystem services (ESS) has become a major concern in planning urban green infrastructure (UGI). The keys to this are urban trees and their dynamic growth in both overall biomass and specific canopy geometry. However, such dynamic growth interacts not only with the abiotic context but also with tree manipulations such as pruning. To address these aspects, this paper proposes a novel theoretical workflow for designing with urban trees by applying a 3D voxel approach. It aims at achieving a quantitative target such as higher leaf coverage without conflicting with other urban functionalities such as traffic and adequate light. We then illustrate how this target guides strategic planning of tree planting and management. Finally, we highlight how this conceptual approach can stimulate further research and technology development to design and manage next generation UGI.