jquery fullcalendar

I am trying to integrate jquery full calendar plugin.. And I want to disable the past dates for selection.. So I can select only dates starting from current date. How is it possible? How can I filter the dates and specify a condition. I am new to jquery.

$(document).ready(function() {
    var date = new Date();
    var d = date.getDate();
    var m = date.getMonth();
    var y = date.getFullYear();

    var calendar = $('#calendar').fullCalendar({
        header: {
            left: 'prev,next today',
            center: 'title',
            right: 'month,agendaWeek,agendaDay'
        },
        selectable: true,
        selectHelper: true,
        select: function(start, end, allDay) {
            var title = prompt('Event Title:');
            if (title) {
                calendar.fullCalendar('renderEvent',
                    {
                        title: title,
                        start: start,
                        end: end,
                        allDay: allDay
                    },
                    true // make the event "stick"
                );
            }
            calendar.fullCalendar('unselect');
        },
        editable: true,
    });
});