We prefer to buy our smoothie ingredients at farmers markets, this is where you will find reginoal fresh products. Alternatively, we do our shopping at organic food stores and markets. If you are not sure where the nearest organic store is, you should be able to find out here: naturkost.de. There may also be farms in your area that sell in their own little "farm store". You may find what you are looking for here: https://www.hofladen-bauernladen.info/adressen/index.php
In the meantime, there are also the so-called Marktschwärmereien, which bring together producers of high-quality food and buyers: https://marktschwaermer.de/de