Garza watched video tapes that his father collected of former National Basketball Association (NBA) post players like Kareem Abdul-Jabbar and attempted to recreate their moves.

Garza led Maret to the District of Columbia State Athletic Association (DCSAA) title game and earned D.C. Gatorade Player of the Year honors.

[5] He was a four-star recruit and chose to play college basketball for Iowa over offers from Georgetown, Georgia and Notre Dame, among others.

[8] Shortly before his sophomore season, Garza underwent surgery to remove a nine-pound (4.1 kg) cyst attached to his spleen.

[14] In an 84–68 win against Iowa State on December 12, Garza had a tooth jarred loose after taking an elbow from teammate Joe Wieskamp.

[25] On November 27, Garza scored a Carver–Hawkeye Arena-record 41 points, including 36 in the first half, on 14-of-15 shooting while posting nine rebounds and three blocks in a 103–76 win over Southern.

[29] On February 21, he recorded 23 points and 11 rebounds in a 74–68 victory over Penn State, surpassing Roy Marble to become Iowa's all-time leading scorer.

[31] At the close of the season, Garza was again named Sporting News Player of the Year, becoming the first repeat winner since Michael Jordan in 1983 and 1984.

[39] On October 23, Garza made his NBA debut, posting three points, two rebounds, two steals and one assist across six minutes of play in a 97–82 loss to the Chicago Bulls.

[40][41] On November 23, Garza made his first career start, scoring seven points on 3-of-5 shooting from the field and 1-of-1 from three, in addition to three rebounds and two assists in a 100–92 loss to the Miami Heat.

[42][43] On December 26, Garza scored a career-high 20 points on 7-of-14 shooting from the field and 2-of-5 from three, to go along with six rebounds and two assists, before fouling out in a 144–109 blowout loss to the San Antonio Spurs.

[46][47] Together with teammates Hamidou Diallo and Saddiq Bey, they became the first trio in league history to register 20 points and 14 rebounds in the same game in over 40 years.

His maternal uncle, Bosnian born Teo Alibegović, husband of his mother's sister Lejla Muftić, was the all-time leading scorer for the Slovenia national basketball team.

His maternal grandfather, Refik Muftić, was an accomplished association football goalkeeper, spending his entire career with FK Sarajevo.