Miller asks you to lend him a pokémon that knows a Water-type move for the farm.

The Request

After you complete Help Wanted: Plowing the Fields, talk to Miller at the Farm in Jubilife Village to accept his request.

Get a Pokémon that Can Use a Water-type Move

Many pokémon can use Water-type moves, especially those that live in water. When you have one, give it to Miller in Jubilife Village. You can swap out this pokémon any time by talking to Miller again.

Reward

After you give Miller the pokémon, the Farm will have more fields. Talk to Colza to request a harvest.