JOHNSTOWN — Chris Harnish and Harnish Brothers Nursery & Pools are both 60 years old. The store, in a building located in front of the house in which Harnish grew up and where his mother still lives, is present even in the faintest memories from his childhood. "It's been here my whole life," Harnish said recently while standing behind one of the two sales counters inside 132 West State St. Extension. "I was born with a shovel in my hand. And now running this is my whole life, pretty much." Harnish assumed ownership of the business after his father died in 2009.  Jack…