I think there was a post earlier about landscape architects, but I can't find it either.

We used Mahoney's in Winchester for our condo association after we were unable to find anyone reasonably priced in Somerville. They have done a good job coming up with a design and picking out plants. We have decided to do the work ourselves, however.

Perhaps try asking at Ricky's in Union Square. He gave me the name of the stone supplier where I got flagstone to build my own patio (located in Arlington).

Not super helpful, sorry.