jQuery UI Datepicker - Restrict date range
$(function() {
$("#datepicker").datepicker({minDate: -20, maxDate: '+1M +10D'});
});
Date:
Restrict the range of selectable dates with the minDate and maxDate options. Set the beginning and end dates as actual dates (new Date(2009, 1 - 1, 26)), as a numeric offset from today (-20), or as a string of periods and units ('+1M +10D'). For the last, use 'D' for days, 'W' for weeks, 'M' for months, or 'Y' for years.