Orchid display is on all year, but 3 exhibits are closed through sometime in 2019. They opened up a bunch of temporary exhibits to make up for it, though.
Code:
https://www.sbg.org.sg/index.php?option=com_k2&view=item&layout=item&id=34&Itemid=58
Jurong Bird Park is a good alternative to the orchid garden.
If you want to grab a bite in Singapore, here is my favorite foodie blogger of all time:
Offhand, you can't go wrong at the Tian Tian Chicken Rice stall at Maxwell Food Center. Can't miss it. Has a long line from opening time, when I went there was a cut out cardboard poster of Anthony Bourdain in front.