A technique for growing high quality bulk hexagonal single crystals using a solvo-thermal method, and a technique for achieving the high quality and high growth rate at the same time. The crystal quality strongly depends on the growth planes, wherein a nonpolar or semipolar seed surface such as {10-10}, {10-11}, {10-1-1}, {10-12}, {10-1-2}, {11-20}, {11-22}, {11-2-2} gives a higher crystal quality as compared to a c-plane seed surface such as (0001) and (000-1). Also, the growth rate strongly depends on the growth planes, wherein a semipolar seed surface such as {10-12}, {10-1-2}, {11-22}, {11-2-2} gives a higher growth rate. High crystal quality and high growth rate are achievable at the same time by choosing the suitable growth plane. The crystal quality also depends on the seed surface roughness, wherein high crystal quality is achievable when the nonpolar or semipolar seed surface RMS roughness is below 100 nm; on the other hand, the crystal grown from the Ga-face or N-face results in poor crystal quality, even though grown from an atomically smooth surface.