json_encode

What value does json_encode need to assign to
$verse_of_the_day_subscribe in order to cause this checkbox to be
checked when the form is updated with the query to the database?
<input type="checkbox" name="verse_of_the_day_subscribe"
id="verse_of_the_day_subscribe">

I have already figured out how to do ones such as: 
<input type="text" name="first_name" id="first_name" size="20"
maxlength="40" />

Thanks, Ron