The visitors, predicted to be at the sharp end of the Palace Shield Premier Division this season, won the toss and put Matt Jackson’s men into bat.
Daniel Woods top scored opening the batting with 34 but only two other players down the order would go on to make double figures.
James Ferguson made 18 and captain Jackson 13 as Torrisholme were bowled out for 130.
Gareth Jennings was the pick of the bowlers with 3-22 while there were two wickets apiece for Ian Walling, Danny Gilbert and Coen Oosthuysen.
In reply, Michael Wellings’ 53 not out saw his side home in the 32nd over, Garstang finishing on 134-4.
Tom Wells also made 23 and Allan Cook 22 as the Riversiders made it two wins out of two.
For Torrisholme, Jackson, Woods, Graham Lee and Callum Steel all picked up a wicket each but their efforts were in vain.
They next host Rufford on Saturday in a game between two sides expected to be battling to stay in the Premier Division this summer.
Torrisholme’s second team went down to a heavy defeat at Blackpool 3rds in Division Three of the Palace Shield.
The hosts made 262-3 batting first, Kawsar Ahmed making a fine unbeaten century, finishing on 139.
In reply, the visitors were bowled out for 54, Iain Parkinson top scoring with 18.