As of July 2023, parking hours are: Mon-Sat 09:00-23:00, Sun 12:00-23:00 and within these hours it cost €5.52/h to park which is extortionate. It is beautiful place though and Het Park is lovely. Best place to park in Rotterdam is Kralingse Zoom park and ride (max height 2.1m), free if you have OV chip card (get it from the metro station attached to the P&R).