The Jambos line-up, which featured David Vanecek, Craig Wighton, Callumn Morrison, Aidan Keena, Conor Shaughnessy and Jamie Brandon, blew away their inexperienced opponents at Oriam.
Morrison gave Hearts the lead in the 19th minute, slipping the ball home after Vanecek had put the winger through on goal.
And Morrison turned provider for No.2, setting up Wighton for a dinked finish.
Evan Galasso pulled one back for Thistle only for Hearts captain Chris Hamilton to restore his side’s two-goal lead with a powerful header from an Andy Irving cross.
Wighton tapped home for 4-1 three minutes after the interval while substitute Euan Henderson fired high into the net for the fifth minutes later.
Irving struck twice in three minutes to take Hearts’ tally to seven while Vanecek got in on the act with 15 minutes remaining.
Henderson got his second to round off the scoring on 78 minutes.
Hearts: Mason, Brandon, Hickey, Shaughnessy, Hamilton, Irving, Morrison, Cochrane, Vanecek, Wighton, Keena. Subs: Silva, Sandison, Ritchie, C Smith, Burns, Henderson.
• The information in this report was gathered from the Hearts and Partick Thistle Twitter accounts.