The exposed end grains of deck boards can begin to look pretty rough over time. Many will crack and split and some will cup. End checks occur more frequently because moisture moves much faster in longitude than in either transverse direction. Lined up in a series they will begin to look like bad dental work.
An effective method of finishing a deck surface is to install a trim board around the perimeter of the deck. This technique is also called picture framing or racetrack decking. You will need to install blocking around the perimeter of the frame to provide support and a solid fastening surface. Picture frame decking is a good way to hide the ends of boards, which will start to crack and look bad over time. Some composite decking materials are hollow which can be concealed at the ends using this technique.
Some deck builders hang the trim board over the edge of the frame by about an inch in order to tuck the fascia board underneath. This allows water to drain off the board’s edge. This subtle detail can do a lot to improve the overall appearance of your deck. You will have to do some planning to achieve the desired appearance. Be sure to consider how your rail system will be attached and how your rail posts will intersect with surrounding decking.