What a lovely and unique botanical garden! It was such a pleasure to visit, and I wish I had come sooner in the day to get more time here before sunset. I missed the butterfly garden time by a few minutes unfortunately which I was really excited about.
Anyway, it is not free - entrance is $25 for adults and $13 for kids.
I was astonished at all the different species of cacti!! So incredible. And you really can lose yourself on the trails here.
I'd recommend at least 2-3 hours to really enjoy your time and take pictures, etc. Maybe even longer if you want to spend some time at the butterfly area!
They also have rotating art exhibits -- apparently they have had Chihuly in the past, and while I was there, they had Jun Kaneko sculptures!
If you are not much of a hiker, and really want to see the natural flora of AZ, this place is definitely for you! Also great for kids and family fun!