Tough to answer but they have all variety of Camelia. I would go with spring time.
Their website lists a Camellia festival in mid-February, so that's probably a great time to go. However, they also said that the Camellias start blooming again in October, and stay through May. See the "What's in Bloom" page on their site for more.
I really don't know. If you visit the Garden in spring you will find the place full of colors and flowers variety
Thanks! Your answer is awaiting moderation.