In our family, we always use Manischewitz concord red wine throughout the year. However, for Passover we have to make sure to buy the bottles that have the P (Kosher for Passover). What ingredients in Manischewitz concord red wine makes it normally “Kosher not for Passover use” and then changes to kosher for Passover.
Thank you for your question.
Essentially wine is produced once a year, and then it is either Kosher for Passover or not. Nevertheless, if they didn’t write That it is Kosher for Passover it could be that wine was bottled on machines that bottle other juices etc. If indeed it doesn’t have a Kosher for Passover symbol, then I wouldn’t buy it for Passover. You can however call the company and ask them directly.