Rails spring server starting up when it is not supposed to and eating up ram on server

Question

I noticed ruby processes (60!) eating up ram on my server... I saw most of them were spring processes which I did not want. See this:

$ ps aux | grep spring 
david    30704  0.0  0.0   7832   836 pts/4    S+   21:02   0:00 grep spring

$ rails c -e production
Loading production environment (Rails 4.1.6)
irb(main):001:0> exit

$ ps aux | grep spring 
david    30798  6.1  0.6 156640 25976 pts/4    Sl   21:02   0:00 spring server | 49 | started 5 secs ago                             
david    30802 46.4  2.6 256888 108364 ?       Ssl  21:02   0:02 spring app    | 49 | started 5 secs ago | development mode                                                              
david    30814  0.0  0.0   7832   836 pts/4    S+   21:02   0:00 grep spring

$ cat Gemfile | grep spring -C 5
group :development do
  gem 'better_errors'
  gem 'meta_request'
  gem 'awesome_print'
  gem 'binding_of_caller'
  gem 'spring'
end

gem 'twilio-ruby'
gem "highcharts-rails", "~> 4.0.0"
gem 'whenever'
$ 

So why are they popping up? If I remove gem 'spring' from Gemfile altogether, this stops... so why is Rails starting the spring server in production console if the gem is in the development group?