Need help about flower bed

My wife wants peri winkles in front bed. Typical one story family home in Meyerland. How close together should they be placed? Should they be in rows and if so, how many? Anything special to know about care. The bed has sprinklers that are currently set to run 5 minutes every other day. Any advice is appreciated. I need some help before talking to landscaper so I have an idea if they are being straight with me. Have some less than good past experiences.