Sussex opener Tom Haines, who has already made scores of 87 and 155 this season, continued his excellent form with an unbeaten 71 as they closed on 118 for three.
Garton said at the close of play: 'We're very happy. It was a good all-round performance from the bowlers and then our batsmen applied themselves really well. It's a good wicket. If you get it wrong batsmen can score freely, but it spun which is unusual for April, but perhaps not so surprising given the weather we've had.
"I knew I had to hit my straps straight away and getting Adam Lyth, who is in such good form, got the ball rolling. It was nice to get Joe Root out, everyone wants his wicket. Someone mentioned I'd got Alastair Cook out last season as well so that's not a bad habit to have to get good players out."
England coach Chris Silverwood and chief scout James Taylor had come to watch Sussex seamer Ollie Robinson and monitor Jofra Archer’s fitness as he continued his recovery from finger and elbow injuries in the nets, but Silverwood would have been impressed with left-armer Garton, who swung the ball consistently at good pace to finish with three for 25 from 11 overs.
The 24-year-old was on England’s radar a few years ago when he joined the squad preparing for the 2017 Ashes in Australia. He then suffered two side injuries but is now demonstrating his all-round skills having made a career-best 97 in last week’s win over Glamorgan.
Openers Adam Lyth and Tom Kohler-Cadmore had put on 60 without alarm after Yorkshire won the toss but Lyth (42) clipped to mid-wicket and Kohler-Cadmore (17) lost two stumps to Garton’s inswinger before England captain Root was leg before trying to work the ball into the onside.
Yorkshire then lost wickets regularly. Gary Ballance, playing his first game since September 2019, was taken at second slip, one of two victims for left-armer Sean Hunt who also dismissed Jonny Tattersall (7), while three wickets fell to spin.
Slow left-armer Delray Rawlins picked up Harry Brook (14), playing back to a ball he should have been forward to, and Dom Bess (17) was caught behind while Jordan Thompson (5) fell lbw to off-spinner Jack Carson.
Robinson had gone wicketless in his new-ball burst, but he returned to end the innings when Steve Patterson (3) edged the second ball of his new spell before taking a simple return catch to dismiss David Willey (13).
There were several soft dismissals and Sussex’s openers put the conditions in perspective, adding 60 without alarm before Aaron Thomason (20) drove loosely at Thompson and was caught at third slip.
Bess briefly had to go off for treatment after hurting his hand fielding, but the England off-spinner bowled 13 wicketless overs after tea. Haines cruised to his third half-century of the season before Duanne Olivier took two late wickets to check Sussex’s progress.