You may notice the leaves of some of your waterlilies getting smaller and smaller. This is normal and natural, waterlilies the hardy or perennial types “know”and they prepare by going dormant. Soon all you will see is a pot in the bottom of your pond. Tropical lilies come from equatorial (tropical) regions of the world they have no mechanism for surviving cold weather. However most tropical waterlilies especially the ones with blue flowers survive most winters here along the Gulf Coast. Tropical Night bloomer are the toughest, they have been known to survive winters as far North as Dallas. There are steps you can take to keep your tropical lily from freezing, but to my mind it is not work the time and expense unless that particular lily has sentimental value.