Dr. Lintner is also the current President of the Audubon Society of Portland and a frequent volunteer at their Wildlife Care Center. She has cared for wild birds both at her private clinic and at the Wildlife Care Center. According to Dr. Lintner, the most important thing is to get all the fecal matter off of the outside of your feeders because that's the single best thing you can do to prevent the transmission of diseases. She recommends a mild soap and hot water, with a good rinse. Use a good scrub brush for cleaning.
Flat ones work great for platform feeders, cylindrical ones for tube feeders.
Make sure they are dried thoroughly before you refill them. If you're in an area where it is dry and cold all winter, you might get by with cleaning your feeders at the beginning of the season. Do a visual inspection each time you fill them. If you see moldy seed, caked on dirt, or bird feces stuck to your feeders, take them down and clean them. For hummingbird feeders, keep them clean and free of mold and fungus.