Head west past the split in the road then go south to reach a different area. Approach the kid and her grandfather and he’ll leave his Berry field to your care. He’ll also give you a tutorial on how to plant and take care of your berries. You’ll receive x5 Oran and x5 Pecha Berries from him as well. To water the berries, you’ll get the Sprinklotad.
You’ll have some free fields where you can plant the berries you got. There are also two composters to the northwest and southeast portions of the field where you compost three berries and turn them into mulch. This mulch will act as a fertilizer needed for the berries to grow faster.
Check the southwest corner of the field as well to get a Miracle Seed. If you have questions about Berry Farming and using the composter, you can talk to the old man and his granddaughter in their house in the northeast corner of the field.
Later in the game once the trees have grown, you’ll also have to remove the weeds and even encounter wild pokemon. You’ll know if there’s a wild pokemon living in your tree when it’s shaking. Leave the field when you’re done.
Continue west and you’ll find a Snorlax sleeping on the bridge. You’ll need the Poke Flute to wake up Snorlax. Your next destination is the Parfum Palace past Route 6. Backtrack to the split in the road then take the upper left road to Route 6.