In a story a friend of mine is working on, there's a planet that is used as a farming world (food) for its system. This planet has a single, Mediterranean sea-sized ocean on it and lacks any other major surface oceans (he hasn't excluded rivers and lakes). Is there any way, given these parameters, for a water cycle that is vigorous enough to sustain farming exist in this world? Can the balance of temperature from day to night in this world be maintained without any surface oceans to balance things? I'm having a hard time figuring out how this planet can work as it's written.

So there's a planet that is used as a farming world (food) for its system. This planet has a single, Mediterranean sea-sized ocean on it and lacks any other major surface oceans (he hasn't excluded rivers and lakes). Is there any way, given these parameters, for a water cycle that is vigorous enough to sustain farming exist in this world? Can the balance of temperature from day to night in this world be maintained without any surface oceans to balance things? I'm having a hard time figuring out how this planet can work as it's written.