Arranging groundcovers in an outdoor plant box can transform your space into a vibrant, low-maintenance garden. Start by selecting the right groundcovers—opt for varieties like creeping thyme, sedum, or ajuga that thrive in your climate and light conditions. Layer them strategically, placing taller or spreading varieties at the back or edges, and compact ones in the front for balance. Ensure proper spacing to avoid overcrowding and promote healthy growth. Mix textures and colors for visual interest, and pair with complementary plants for a cohesive look. Regular watering and occasional pruning will keep your plant box lush and thriving year-round.