You can attach any 3rd party control for search control in the toolbar, such as a datepicker.

The search file (textbox) has ID equal to the DateField of the columns, with "gs_" prefix. So you can obtain it with jQuery in the client-side GridInitialized event and hook the datepicker inside.

Please, refer to ASPX code tab for details.
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="default.aspx.cs" Inherits="GridTest.examples.searching.search_toolbar_datepicker._default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>jqGrid ASP.NET example with SqlDataSource</title>
    <!-- The jQuery UI theme that will be used by the grid -->
    <link rel="stylesheet" type="text/css" media="screen" href="/themes/redmond/jquery-ui-1.8.2.custom.css" />
    <!-- The jQuery UI theme extension jqGrid needs -->
    <link rel="stylesheet" type="text/css" media="screen" href="/themes/ui.jqgrid.css" />
    <!-- jQuery runtime minified -->
    <script src="/js/jquery-1.4.2.min.js" type="text/javascript"></script>
    <!-- The localization file we need, English in this case -->
    <script src="/js/i18n/grid.locale-en.js" type="text/javascript"></script>
    <!-- The jqGrid client-side javascript -->
    <script src="/js/jquery.jqGrid.min.js" type="text/javascript"></script>    
    <!-- This jQuery UI library is needed only for the code tabs, not needed by the grid per se -->
    <script src="/js/jquery-ui-1.8.2.custom.min.js" type="text/javascript"></script>    
    <style type="text/css">    
        body, html { font-size: 80%; }    
    </style>
</head>


<body>
    <form id="form1" runat="server">
    
    <asp:ScriptManager runat="server" ID="ScriptManager1"></asp:ScriptManager>

    <asp:SqlDataSource runat="server" ID="SqlDataSource1" 
        ConnectionString="<%$ ConnectionStrings:SQL2008_449777_fhsConnectionString %>"        
        SelectCommand="SELECT [OrderID], [RequiredDate], [ShipName], [ShipCity], [Freight] FROM [Orders]">
    </asp:SqlDataSource>        
    
     <asp:SqlDataSource runat="server" ID="SqlDataSource2" 
        ConnectionString="<%$ ConnectionStrings:SQL2008_449777_fhsConnectionString %>"                 
        SelectCommand="SELECT DISTINCT [ShipCity] FROM [Orders]">
    </asp:SqlDataSource> 
      
    <div id="containerID" runat="server">
        <trirand:JQGrid runat="server" ID="JQGrid1" DataSourceID="SqlDataSource1" 
            Width="600px" onsearching="JQGrid1_Searching" >
            <Columns>
                <trirand:JQGridColumn DataField="OrderID" Searchable="false" HeaderText="Order ID" PrimaryKey="True" Width="50" />
                <trirand:JQGridColumn   DataField="RequiredDate" 
                                        Searchable="true" 
                                        SearchDataType="Date" 
                                        SearchToolBarOperation="IsEqualTo" 
                                        DataFormatString="{0:d}"/>
                <trirand:JQGridColumn DataField="ShipName" Width="200" SearchToolBarOperation="Contains" />
                <trirand:JQGridColumn DataField="ShipCity" SearchType="DropDown" 
                                    SearchToolBarOperation="IsEqualTo" SearchControlID="DropDownList1" />
                <trirand:JQGridColumn DataField="Freight"  SearchType="DropDown"
                                    SearchValues="[All]:[All];10:> 10;20:> 20;30:> 30;50:> 50" SearchToolBarOperation="IsGreaterThan" />
            </Columns>
            <ToolBarSettings ShowSearchToolBar="true"/>            
            <ClientSideEvents GridInitialized="hookSearchDatePicker" />
        </trirand:JQGrid>
    </div>   
    
     <script type="text/javascript">

        function hookSearchDatePicker() {
            $("#gs_RequiredDate").datepicker({
                changeMonth: true,
                changeYear: true,
                dateFormat: "mm/dd/yy",
                onSelect: function(dateText, inst) {
                    $("#gs_RequiredDate").focus();
                }
            }); 
        }
    
    </script>
    
    <asp:DropDownList runat="server" ID="DropDownList1" DataSourceID="SqlDataSource2"
        DataTextField="ShipCity" 
        DataValueField="ShipCity" 
        AppendDataBoundItems="true">        
        <asp:ListItem Text="[All]" Value="[All]"></asp:ListItem>
    </asp:DropDownList>
    
    <br /><br />
        
    <trirand:codetabs runat="server" id="tabs"></trirand:codetabs>         
       
    </form>
</body>
</html>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace GridTest.examples.searching.search_toolbar_datepicker
{
    public partial class _default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void JQGrid1_Searching(object sender, Trirand.Web.UI.WebControls.JQGridSearchEventArgs e)
        {
            if (e.SearchString == "[All]")
                e.Cancel = true;
        }
    }
}
Switch theme:


Theming is based on the very popular jQuery ThemeRoller standard. This is the same theming mechanism used by jQuery UI and is now a de-facto standard for jQuery based components. The benefits of using ThemeRoller are huge. We can offer a big set of ready to use themes created by professional designers, including Windows-like themes (Redmond), Apple-like theme (Cupertino), etc. In addition to that any jQuery UI controls on the same page will pick the same theme.

Last, but not least, you can always roll your own ThemeRoller theme, using the superb Theme Editor

To use a theme, simply reference 2 Css files in your Html <head> section - the ThemeRoller theme you wish to use, and the jqGrid own ThemeRoller Css file. For example (Redmond theme):

<link rel="stylesheet" type="text/css" media="screen" href="/themes/redmond/jquery-ui-1.8.1.custom.css" />
<link rel="stylesheet" type="text/css" media="screen" href="/themes/ui.jqgrid.css" />