Texas Rangers

The Texas Rangers selected Gardewine in the seventh round, with the 220th overall selection, of the 2013 MLB Draft.^[2][3] He signed with the Rangers, and pitched in Minor League Baseball for the Arizona Rangers of the Rookie-level Arizona League in 2013 where he was 3–3 with 3.21 ERA in 14 games.^[4][1] In 2014, Gardewine pitched for the Spokane Indians of the Class A-Short Season Northwest League, and had a 6–3 win–loss record and a 4.54 ERA. He played for the Hickory Crawdads of the Class A South Atlantic League in 2015, and had a 6–8 win–loss record and a 4.31 ERA. While pitching for Hickory, Gardewine tore his supraspinatus muscle. He rehabilitated the injury into the 2016 season, where he became a relief pitcher for the High Desert Mavericks of the Class A-Advanced California League.^[4] In 29 relief appearances for Hickory in 2016, he was 5–1 with a 2.47 ERA.^[5] Gardewine began the 2017 season with the Frisco RoughRiders of the Class AA Texas League.^[1]

The Rangers promoted Gardewine to the major leagues for the first time on August 21, 2017.^[6][7] Gardewine appeared in 12 games for Texas in 2017, producing a 0–0 record, and 5.63 ERA in 8 innings.

In 2018 Gardewine appeared in 3 games for Texas, posting a 0–0 record, and 3.60 ERA in 5 innings. He appeared in 12 games for the Round Rock Express of the Triple-A Pacific Coast League, throwing 12 innings with a 2–1 record, 7.30 ERA, and 17 strikeouts in 12 games. Gardewine was placed on the AAA DL on May 17, 2018 with a right forearm strain.^[8] Gardewine spent the rest of the 2018 season rehabbing his injury and did not appear in another game. Gardewine was placed on the MLB 60-day DL from August 25 - November 2, 2018.

In 2019, Gardewine was optioned to the Nashville Sounds of the Triple-A Pacific Coast League to open the season, and appeared in four games before being shut down for the season due to injuries.^[9] On June 8, he was designated for assignment.^[10] On June 13, he was released by Texas. On June 19, he signed a two-year minor league contract with the Rangers.^[11] Gardewine was released by the Rangers organization on June 1, 2020.

Cleburne Railroaders

On May 7, 2021, Gardewine signed with the Cleburne Railroaders of the American Association of Professional Baseball.^[12] Gardewine appeared in 1 game with Cleburne, pitching a shutout inning with 3 strikeouts.

Arizona Diamondbacks

On May 20, 2021, Gardewine’s contract was purchased by the Arizona Diamondbacks organization.^[13]

Cleburne Railroaders (second stint)

On April 29, 2022, Gardewine signed with the Cleburne Railroaders of the American Association of Professional Baseball.^[14] Gardewine appeared in 42 games for Cleburne in 2022, recording a 5-4 record and 2.72 ERA with 15 saves and 59 strikeouts in 43.0 innings pitched.

On January 23, 2023, he was released by the Railroaders.^[15] Gardewine re–signed with Cleburne on June 17.^[16] Gardewine became a free agent after the 2023 season. In 24 games 23.1 innings he struggled mightily going 2-3 with a 6.17 era and 24 strikeouts.