St. John's wort is an herb, not a homeopathic remedy, in the way you're talking about it. It does exist in homeopathy, and is called hypericum when it is, which is the Latin name for the plant. For some people St. John's Wort has proven very effective for depression. For others, not so much. You have to try it to tell. Usually, herbal medicine is used in combinations, not just one herb, but you can try it.