Throughout the year. It's easier to ask when it is not a good time, and I would imagine during the winter. Understand, they have music and entertainment, so if you look up specific dates you can maximize your experience by compounding it with a nice musical ensemble or event. I would look at the Web site, but things are always in bloom. You will have a different experience depending on when you go. They usually close around 4 or 5 but sometimes stay open late. Give yourself two hours and you won't have to rush. The hours are posted.
Anytime the weather is nice
Thanks! Your answer is awaiting moderation.