We are first time chicken owners, and currently have 6 chicks (4 are 3 weeks, 2 are 2 weeks.) They are thriving on the medicated chick feed they receive, but I wondered when we are able to/should begin to introduce some greens (lettuce/grass etc? I haven't found any mention of it in the reference books I have....other than when we can begin to give them some outside introductory range time around 5-6 weeks. Any thoughts would be appreciated. Thanks!