How do monsters level in your farm?

The monsters gain experience as you adventure, as I understand it the monsters on your farm gain experience as your monsters do, but the ones of the farm will earn less.

I couldn't find much of anything really for reference material, but here is the best link I could find: http://tartarus.rpgclassics.com/dwm/basics.shtml#farm

On the top floor of GreatTree castle you will find the monster farm. This is run by a boy called Pulio who can help you out by keeping monsters and eggs for you. The farm can hold a maximum of 38 monsters, 19 current monsters, and 19 sleeping monsters. Any monsters that you leave in the farm will still get a little experience when you are adventureing, but not as much as the monsters in your party. Any mopnsters that are sleeping in your farm will not get any experience. When you speak to him he gives you a list of options:

• DROP OFF - This enables you to drop off monsters with Pulio, however you cannot drop off a monster if you only have one, or if the storage limit is full, in these cases Pulio will offer to swap a monster.
• PICK UP - This gives you the option of taking a monster out of the farm to put in your party. If your party is full then Pulio will offer to swap one of your monsters.
• CHECK - This lets you check the status of the monsters in the farm.
• SEPERATE - This option wil allow you to seperate a monster from your farm. This will release it from your farm back to the wild. This should only be used if you really need space on your farm and have some monsters that you don't mind losing, as the monster will be lost permently.
• SLEEP - This will put all the current monsters on the farm to sleep, and will wake up any already sleeping monsters. If you choose this option then your game will also be saved.
• EXIT - This will stop talking to Pulio.