This is a hidden jewel for sure. I took my wife on a surprise outing this morning, as a friend of mine who volunteers here told me about it.
The $5 admission price gets you a slice of peace and tranquility. Spend the morning walking around the large koi pond, which contains some of the biggest and most colorful fish I've had the pleasure of gazing upon.
I was told that on the 2nd Saturday of each month, they host an authentic tea ceremony, back in the tea gardens. The general public is not allowed in that area without a 'docent', which is kind of a tour guide. You should call to make a reservation if you wish to attend. The current per person price is $25.
If you are looking for some quiet volunteer work, they will allow you to come down and lend a hand. Not sure if you need to make arrangements first.
Is this a Japanese Garden, or a Japanese Style Garden? I suggest you take up that conversation with volunteer Fred.