After visiting Camphrier Town and Shabboneau Castle, you follow the keeper of the castle to Route 7.
Visit the Berry Farm
When you go west on Route 7, you soon reach a fork in the road, with a path going south. If you go south, you find a Berry Farm. The guy there asks you to help at the berry farm. If you want to help out, say yes. The man will give you some Oran and Pecha berries and ask you to plant them in the soft soil. He also gives you a Sprinklotad that you can use to water the berry plants if the soil is dry. After that, the man and his granddaughter go back to their house at the corner of the field.
In the northwest of the field, there is a composter. You can put three berries in to create Mulch. Use Mulch by putting it on soft soil that you haven't planted a berry in. Then plant a berry there. The type of mulch that comes out depends on the types of berries that you put in. For example, to make Rich Mulch, put in three different colors of berries. If you have mulch, then when you check on unplanted soft soil, you'll be asked if you want to use mulch.
A Note about Mutations
Planting different kinds of berries next to each other might result in mutations, where one of the berries on the tree is different from the type that you planted there. If this happens, a researcher will go to the house in the berry field and will keep a record of the mutations that you have discovered.
Explore the Farm
In the southwest corner of the berry field, there is a Miracle Seed. If a pokémon holds a Miracle Seed, the pokémon's Grass-type moves will be stronger.
There is another composter in the southeast corner of the field.
The grandpa and granddaughter's house is in the northeast corner of the field. Talk to the grandfather to learn more about planting berries. You will learn that weeds might grow where you planted a berry, so be sure to check on it to pull the weeds. Also, Bug-type pokémon might eat the berries from the trees, so check on a shaking tree to battle the Bug-type pokémon that is eating the berries.
The granddaughter will tell you about mulch. She says that the type of mulch that is created depends on the color of the berries. She also says that there are three different effects that mulch can have, but you'll have to find out what they are yourself. One of the effects is that you can increase the number of berries on the tree, and another effect is that you can increase the chance of mutations.
Leave the berry farm and go west on Route 7. You'll discover that a Snorlax is sleeping on the bridge, blocking the way. The black belt used to have a Poké Flute that would wake Snorlax up, but the owner of Parfum Palace took the flute. Shauna says that Parfum Palace is just past Route 6, which you can reach by going east from here, then north.
Before you go, you should walk north from the bridge through a narrow path in the grass. At the end of the path, you find a Heal Ball. If you catch a pokémon with it, that pokémon will be completely healed up as if you had taken it to a Pokémon Center. It's useful if you have an empty spot in your party and want to use a caught pokémon right away.
When you're ready, go east from the Snorlax bridge, then north up Route 6, Palais Lane.