The Gravity Forms date field uses the jQuery UI datepicker, which makes it highly customisable and coupled with the gform_datepicker_options_pre_init Gravity forms filter you can easily make the datepicker work how you want it.
In this article, I’ll show you how to disable weekends or specific days with just a few lines of code.
Firstly, if you just want to disable weekends then you just need to add these few lines of code to your WordPress theme’s functions.php file. On the form’s date field you need to go to the Appearance section and add no-weekends in the “Custom CSS Class” field.