Hello
I know this topic is over a year old, but since it is one of the first google search results for "jquery mobile textarea autogrow" I guess its ok to post an answer:
The autogrow-functionality is called whenever the textarea receives a "keyup"-event. Textareas will only grow, but not shrink. To manually let the textarea grow simply fire the keyup-event on that textarea. example:
- $('#textarea').trigger('keyup');
That's all you have to do.