git doesn't push .env file on the server
Laravel, by default, ignores the .env
- this is very much intended, as your different environments should technically have, well, different env
files. It also helps you from not submitting credentials (such as for your database) into version control.
I would recommend you continue to follow this intended practice and look into using heroku config variables:https://devcenter.heroku.com/articles/config-vars