The popular iPhone application, Plants vs. Zombies ($2.99), has recently been updated. Now, fans of the application can enjoy a variety of new features, including a “Zen Garden,” mini-games and brand-new achievements.

While the iPad version of the application (Plants vs. Zombies HD) hasn’t yet received the update, iPhone and iPod touch users can enjoy the new features (in version 1.6 of the application). As outlined in the app’s release notes, changes made in the update include:

Zen Garden – Collect and grow your own collection of plants. Water them every day and they’ll reward you with a bounty of coins to spend in Crazy Dave’s shop. You’ll be able to get the mushroom garden and underwater garden, too!

Minigames – Crazy Dave’s shop is expanding and will have some brand-new minigames to offer. Will you start with Zombiquarium or Zombotany? How about It’s Raining Seeds?

Achievements – Oh, you know that with new content come new achievements to unlock. Of course, these new achievements are tied into Game Center so you can show them off to your friends.

Furthermore, the app’s developer (PopCap) assures Plants vs. Zombies fans that the “long-awaited Retina display update” is coming very soon.

We’ll let you know when it’s available. In the meantime, check out the updated version of Plants vs. Zombies in the App Store. As mentioned, it’s currently available to download for $2.99.