Passes that have not yet been mailed out can be upgraded via your original order confirmation.
Click on the grey 'VIEW YOUR RECEIPT OR QR CODES HERE' link from your GrowTix order confirmation email. This will bring you to your ticket confirmation page, where you can click on the UPGRADE button beside the ticket you would like to change. If the new admission is more, you will be prompted to pay the price difference. Note that no refunds will be issued, and once a certain ticket type sells out, it will no longer be offered as an option for your Upgrade.
If you are not seeing a button for UPGRADE, please contact us to provide further assistance. Be sure to include the email address that was used to purchase the ticket originally.