how can i use addMonth() function with a string type not current date variable in laravel?

I am using a variable $Date which comes from my view page. $Date = Input::get('Date'); Now I want to add a month with the variable named $Date. I can use it with current date using Carbon::now()->addMonth(1). How can i use that addMonth() function for a string variable $Date which is not current. The format of $Date variable is 'Y-m-d' Please helpe me...

via Chebli Mohamed