Plant your coleus in a soil that is abundant with organic substances such as composted cow manure, peat moss or compost. A rich soil provides the nutritional foundation for a healthy plant.
The Alabama Cooperative Extension suggests you apply a 20-10-20 fertilizer, either granular or liquid, at every fourth watering. Watering should take place when the soil is just a bit dry, usually once or twice a week.
Maximize the denseness of your coleus by feeding it a commercial foliar growth retardant to discourage vertical growth. Energy is then concentrated on branch growth, and this results in fuller, bushier leaves.