Unfortunately, there's not much you can do other than management methods that prevent access to the plants or supervision. The doggy door is a good thing in that it gives her access to the outside without you playing "doorman", but it's also a bad thing in that it gives her unsupervised access to the outside (and to trouble). Basically, to a 1 year old dog, plants in the ground and plants in pots are "fair game" and fun to play with. Probably much more fun and rewarding than her own toys. Just pulling the plants out is a highly rewarding game to her.
Here's some suggestions.
1. Don't give the one year old free access to the doggy door and go outside with her everytime she needs to go out. (plus make sure she is getting enough exercise in terms of walks and also make sure she is getting "mental" work in terms of obedience training and jobs to do). This is basically giving her more supervision and more organized activities and less free time. If you need help with obedience training to find a trainer in your area go to http://www.personalizeddogtraining.com/ and click on the Puppy Manners button and then in the index, click on Find a Trainer and that will take you to links where you can search for a trainer by your zip code.
2. Somehow place the pots out of her reach - put them somewhere else, fence them off, but them up high so she cannot reach them.
3. Or get an invisible fence type of barrier and train her to understand what it means (this can work, but these fences do cost money and proper training is needed so that the dog will understand it and not get upset).
4. Maybe she will eventually grow out of this - which is more likely if she is prevented from doing it so it does not remain so rewarding for her (thus, doing either 1, 2, or 3 is important.)
Unfortunately, it's not in a dog's "vocabulary" "yours versus mine". For dogs, "yours versus mine" basically means that whoever has the valued object at that time, then it's mine. Yours versus mine does not mean that they learn to leave something that's fun to play with alone when you are not there to supervise.
If you plan on not giving doggy door access to your 1 year old and to supervise her when she's outside, then you can teach her a simple "leave it" command. But you will have to be consistent and supervise for quite a long time before you could ever trust her alone around your plants. An obedience instructor could help you with the steps needed to teach "leave it" - see above to find an instructor in your area.
Hope this helps you solve the problem. There is basically no quick/easy/magic fix. Mostly management solutions.