My frank review: I found this castle supremely disappointing. I thought it was lacking in historical information throughout and that some of the information that was presented was missing proper context. The Percys no doubt make a lot of money off of the pop culture connections (Harry Potter, Downton Abbey), and that is the true draw to the site. It was also bizarre to visit a castle that is still inhabited.
Various photos throughout the gardens. It was a lush summer day with buzzing bees and endless blooms. I was supremely impressed with the gardens and highly recommend a visit. We took the train to Alnmouth from York then hopped on the short bus ride to Alnwick to visit the gardens and the castle.
This garden is accessible by guided tour only, as it houses only poisonous plants, including some Class B drugs. Interestingly, many of the plants are common household plants such as nettles, poppies, rhubarb, and laurel.