They used to have a website which will tell you when the azaleas are approaching their peak, it's probably still in operation.
Any time of the year they have spring flowers inside the Butterfly sanctuary which is a climate controlled environment.
I was there at Christmas and it was beautiful. Not sure about the flowers.
Spring time
When the azaleas are in bloom.
Between March and April
When the Azelas are blooming. They usually post their times.
Late April
April
Late April depending on weather
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