Some visitors may shy away from visiting the gardens during the winter, but there are actually things to do and see all year round. There are a number of indoor gardens (the Climatron - rainforest, the hothouse - desert, home garden education center, etc).
They also list events year round on their website. Growing up my family always went to the "Dinner with Santa event" which was great, but I couldn't vouch for it now. (Just a nice childhood memory :)
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