Dietrich is currently playing for Double-A Jacksonville, where he is starting to heat up. He's riding a four-game hitting streak, going 9-for-14 in the stretch.
He did exit after an RBI single for the Suns on Thursday due to back spasms.
Over his last 10 games, Dietrich is hitting .412. For the season, the former Georgia Tech star is hitting .271 with 11 homers and 38 RBIs at Double-A.
Dietrich spent time this season with the Marlins, getting promoted in early May due to an intercostal injury to Donovan Solano.
In 57 games with Miami, the rookie batted .214 with nine homers and 23 RBIs. Combining his big league and Minor League totals, Dietrich has connected on 20 homers.
Still, there are parts of his all-around game the club would like to see improvement, which is why he will be heading to the Arizona Fall League.
"We're looking for him to be more consistent in the strike zone and hit some offspeed pitches," Miami manager Mike Redmond said. "He's still got areas of his game he needs to sharpen up and work on. We talked about when he came up that he really wasn't a guy we anticipated coming up when he did. He did a nice job and he learned a lot. At the same time, too, the Fall League is a good time to extend his season a little bit. Give him some more time and give him the best opportunity to come into Spring Training and make the team."
Also heading to the Arizona Fall League is lefty Andrew Heaney, 22, the organization's top pick in the 2012 First-Year Player Draft. Miami's No. 2 prospect is a combined 9-3 with a 1.60 ERA overall at Class A Jupiter and Jacksonville. Since joining the Suns, he is 4-1 with a 2.94 ERA in six starts .
Third baseman Colin Moran, Miami's first-round pick this season, also will be heading to Arizona. So is lefty reliever Edgar Olmos, 23, who had a brief stint with Miami and is now at Double-A.
Right-handed relievers Nick Wittgren and Colby Suggs are on the list, as is Double-A outfielder Brent Keys.