Ruby 1.9.3 and Rails 3.2 on Heroku Heroku’s newest stack, “Celadon Cedar,” supports Rails 3.2 but installs Ruby 1.9.2 by default. Ruby 1.9.3 is recommended for Rails 3.2.
You can configure the Heroku environment to use Ruby 1.9.3.
Note: Heroku makes it clear that Ruby 1.9.3 on Heroku is experimental, which means “no support, the ruby_version will change in the future, and this feature may change or be removed without warning.” In response to an inquiry on January 31, 2012, Heroku said, “there is no timeline yet” to fully support Ruby 1.9.3.
Install the heroku-labs plugin: