Supertunia petunias are vigorous with slightly mounded habits that function as both fillers and spillers in containers.  They are also excellent landscape plants, best suited to be placed near the front of beds.  They have medium to large sized flowers.
 
These are heat tolerant plants, that aren't particularly fussy and need little routine maintenance. They will perform best if an application of controlled release fertilizer is included at the time of planting. This applies to both landscape and container plantings. Supertunias are heavy feeders, but a single dose is usually sufficient for landscape beds in most climates. If you have a very long season, a second application of controlled release plant food should be considered for landscape plantings. In general, containers need to be fed more than landscape plants. Supertunias in containers will need to be fed more regularly to be their absolute best. A second application of a controlled release fertilizer can be applied about every two months to container plants, which will help. However, for the very best performance I find regularly applying water soluble fertilizer starting about two months after the containers are planted gives the best results.  These extra applications of plant food really makes a difference in performance through the summer.
 
If your plant begins to look open or a bit tired, an allover trim can be beneficial.  Use a sharp pair of scissors or pruning shears to trim back up to 1/3 of the volume of the plant. I pair any trim with a dose of water soluble fertilizer to provide instant energy to help kickstart new growth, branching and flowering. Your plant will take a week to recover from the trim, but the end result is a fuller plant with more blooms going forward. You may repeat the trim as needed through the season.