You can choose one time zone per Zope instance, and all the Plone sites within that instance will have the same time zone settings.  To change the time zone, you need access to your Zope instance on the file system.

In the 'bin' directory, make a backup of the runzope file using a command like "cp runzope runzope.YYMMDD" - where YYMMDD is the year, month and date.  Then open runzope in a text editor.

First, add a line just below PYTHONPATH to define the TZ variable, such as:

TZ="GMT"
TZ="America/New_York"
TZ="America/Los_Angeles"

Then add either:

export TZ

Or, if you already have an export line in the runzope script, add TZ to the end of it, like this:

export PYTHONPATH INSTANCE_HOME SOFTWARE_HOME TZ

You will need to restart the Zope server for that instance before the change will take effect.

Helpful Links

• The tz database
• Time Zone Reference Card (from timezoneconverter.com)
• Date and Time Gateway (TWiki.org Service)
• Editing with vi (A short summary from Colorado State)
• How do I change Zope's Timezone (from Zettai.net)
• Make Zope work with GMT (from Zettai.net)