how often should you change hummingbird food
Preventing Mold and Fermentation. 1  1. Know that your food can cause harm if left to ferment or mold. 2  2. Check your feeder for black mold as often as you can. 3  3. Clean your feeder before your refill it.  4. Change the food in the feeders regularly. Be aware that the amount of time you can leave hummingbird food outside depends on the temperature in which the feeder is hung in. If temperatures are 70 to 80 degrees Fahrenheit (21 to 26 C), change the food every 5 to 6 days.