mush up

No — say "He mushed up the potatoes.". no 'of' is needed between the particle 'up' and the object.

Definition

phrasal verb. to crush something until it becomes soft and thick, like a paste. You might do this to food for a baby or when mixing ingredients.

phrasal verb. to reduce a solid substance to a soft, pulpy mass through crushing or mashing. Transitive; often used in culinary or domestic contexts.

simple

“Mush up the bananas before you add them to the cake mix.”

contextual

“The toddler spent more time mushing up his peas than actually eating them.”

complex

“The artist decided to mush up the wet clay and start the sculpture from scratch after the first attempt failed.”

This is a casual way to describe mashing or crushing something soft.

Contrast with 'mash' (more standard) and 'crush' (implies harder pressure); 'mush up' often implies a messy or informal result.

He mushed up of the potatoes.

He mushed up the potatoes.

no 'of' is needed between the particle 'up' and the object.

Particles

up

Separability

optional

Pattern

mush + up + object