…..from your water garden this fall. As the days shorten, your Hardy Water Lilies will slow their growth and eventually stop growing all together. You will notice fewer and smaller leaves. Stop fertilizing your lilies by October and let them go to sleep for the winter. Simply leave the pot in the bottom of the pond. Your fish will perk up with the cooler temperatures during the fall. Although not totally necessary, you can switch to a Spring and Fall Food to fatten them up for winter.