Ren Ventura

Simply install the plugin and add the appropraite CSS class to the form field you want to assign an attribute. This is done within the Form Editor under the Advanced tab of the field. The classes are “disabled” for the disabled attribute and “readonly” for the readonly attribute (don’t include the quotation marks).

Disable Gravity Forms Fields

This is a simple plugin that lets Gravity Forms users set a form field's attribute to either disabled or readonly.

bradvin

<blockquote>
This plugin is an add-on for the amazing Gravity Forms Plugin. 
 Check out my other free <a href="http://themergency.com/gravity-forms-addon-plugins/" rel="nofollow ugc">Add-ons for Gravity Forms</a>
</blockquote>
Compatible with Gravity Forms v1.7.2
Requires at least v1.5 of Gravity Forms
“Ready Classes” were introduced in Gravity Forms 1.5. Using these new classes, you can easily create more advanced alternative layouts for the fields in your forms. Excellent idea, however, the problem is you always need to remember what the exact class name is. Now with the CSS Ready class selector, you don’t need to remember. Simply click on a button to lauch the popup and choose the class you want to add from the list.
features
<ul>
<li>Convenient button added under the advanced tab next to the “CSS Class Name” field</li>
<li>Clean and simple popup that lists all the “Ready Classes”</li>
<li>Add more than one “Ready Class”</li>
<li>Double click a “Ready Class” to add it and auto-close the popup</li>
</ul>

Gravity Forms CSS Ready Class Selector

Easily select a CSS "Ready Class" for your fields within Gravity Forms

Disable Gravity Forms Fields vs Gravity Forms CSS Ready Class Selector