groundhogs are usually considered pests to farmers. But i think they are cool and can understand your not wanting to get rid of it or see any harm come to it. If the hog wants at your plants, the hog will most likely get them. But you can try completely encasing the root zone in wire. They can dig like ... er ... well groundhogs which is to say - very well.
Here is a true groundhog story - an older fellow I know used to hunt groundhogs as a favor to farmers and to put meat on the table. Before you turn up your nose, keep in mind this was during the depression and this fellow was quite poor.
Anyway, this guy - a young boy then would hunt the groundhogs with his beagle. Now beagles are smart and good trackers and if the dog wasn't held back, would follow the groundhog right into his hole. And holding back the dog is a good idea since the groundhog will fill the hole behind him so the dog can't follow anymore. and the groundhog will, if given the chance, fill in the other side of the hole and trap the dog underground. The only way to rescue the dog is to dig it out.
So the moral of the story - groundhogs are pretty crafty creatures and the hog takes a hankering for tomatoes he will most likely get them.
