The Berry Pots
Since the days of the original Gold & Silver, the whole aspect of Berries has changed considerably. In those games, the Berry trees were few and far between, but you could pick berries from them once a day. This is no longer the way the games work.
In Heart Gold & Soul Silver, you will find Berries dotted around Johto & Kanto, as gifts or found with the Dowsing MCHN. However, the is no loamy soil in these regions for you to plant the Berries. Instead, there is a new key item called the Berry Pots. In this key item, you have four pots so you can grow your Berry trees yourself without having to go back and check on them. Like the growing of berries in Ruby onwards, you will need to monitor these at regular intervals.