How often to change the Humming bird nectar will
be determined by the outside temperature. The hotter the temperature the more
often it will have to be changed. As a general guide, if the temperatures are
cooler you can get by changing the Humming bird nectar once a week. If the temperatures are
in the 70s change every 5 or 6 days, if in the 80s change every 3 or 4 days, if
in the 90's change every 1 or 2 days.
clipped from: howtoenjoyhummingbirds.com