It might be so that the batters don't lose their vision of the ball after it is thrown by the pitcher.
The ivy at Wrigley Field turns green about mid-May. Until then, the ivy is brown.
Wrigley Field wall
Ivy
1939 by Bill Veeck
Wrigley Field
Boston Ivy
Wrigley Field is located in Chicago ILL
Wrigley Field shares its name with the Wrigley Company, as the park was named for its then-owner, William Wrigley Jr., the CEO of the Wrigley Company.
According to www.cubs.com, the capacity of Wrigley Field is 41,160.
Wrigley Field is located at 1060 West Addison Street, Chicago, IL, 60613.
what is the total acreage of chicago wrigley field
When a baseball gets stuck in the ivy at Wrigley Field, the umpire typically calls for a ground rule double. This means that the batter is awarded second base, and any runners on base advance two bases from where they were at the time of the pitch. The ivy-covered outfield wall is part of the unique character of the park, and such occurrences are considered a natural part of the game there. Players often try to dislodge the ball, but if it remains stuck, the ground rule is enforced.