How do you test if something is older than 3 months?

I have been having some trouble to select the rows of my table which has a date of 3 months prior of today. I tried using DATE(NOW() - INTERVAL 3 MONTH) in my where clause, but no luck. How do I check in SQL Server if a item is older than 3 months?

  UPDATE[TCTdb].[dbo].[Stock]
     SET[Warehouse] = 'old'
   WHERE [ManufacturedDate] <= DATE(NOW() - INTERVAL 3 MONTH)