Carnations are easy to grow but require certain planting conditions to thrive. The bushier border garden carnation grows best in full sun. In areas with hot summers, plant the carnations in a location that gets morning sun and is shaded from the hotter afternoon sun. Choose a site with good air circulation to reduce problems with diseases. The best soil for carnations is a rich, well-drained loam. Enrich poorer soil several weeks to a month before planting the carnations. Carnations prefer soil that is slightly alkaline.