Both newbies and seasoned gardeners make this mistake: crowding too many plants into a space. When plants are overcrowded, the look may be lush, but plants can’t reach their full potential. In this garden, two years after planting, the purple coneflower and yellow coreopsis had vanished, overshadowed and elbowed out by the other plants. Always read pot tags to learn how much space each plant needs to thrive. Give plants ample room to ensure the best growth.