Greene split his season between Memphis, where he batted .234, and Double-A Springfield, where he hit .259. For Springfield, Greene had 16 homers and 41 RBIs in 97 games.
He was a first-round Draft choice out of Georgia Tech in 2005's First-Year Player Draft.
Scherer, a right-hander, worked in 40 games for Memphis with a 2-3 record and 3.93 ERA. He was a 16th-round Draft pick in 2004.
The Cardinals also signed left-handed reliever Ian Ostlund to a Minor League contract and invited him to Major League Spring Training. He was a free agent from the Detroit Tigers' organization.
Ostlund was 3-0 with a 2.45 ERA last summer for Triple-A Toledo. He had 77 strikeouts and just 17 walks in 69 2/3 innings. In 299 career Minor League games, he has a 28-21 record, 26 saves and a 3.15 ERA.
The Cardinals have 37 players on their roster, three under the limit.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.