I look at UBC Garden as two different places.
1) The first is the Japanese Garden, which is more of a rainforest atmosphere. That is more trees than garden. And in there you'll find the tree tops adventure, several suspension bridges. Even though they are secure, it can be a workout, keeping your balance while navigating through. For me, more of a workout than Capilano, but it's not difficult.
If you do take the tree top adventure and Ian or someone from the company is there, take a few minutes and start a conversation. The suspension bridges are run by a private company, who has locations all over the world. I'm glad I stopped to talk.
2) The second part is the garden part, as you'll see in the picture above. I was there in August and didn't see a whole lot of flowers in bloom, but still a very nice walk through the park