The easy answer is, "When they're dirty." In an ideal world, you would have the time and energy to clean your windows anytime you want. But, it's not always the case. The dirt and grime will accumulate over time.
Factors like the climate and where you live come into play. Make window cleaning a regular part of your home's maintenance like gutter cleaning. Dirt, dust, mold and other pollutants can get caught any time of the year.
You can use the seasons as a guide for cleaning your windows. Make it a part of your spring-cleaning. Clean them before winter comes so they're bright and shiny for those holiday parties. Clear any grit and grime so you can let all the light shine through during the summer.
Dos and Don'ts of Window Cleaning
Do
Have Proper Equipment: A steady ladder, a hose, and a soft cloth or sponge are your basic window cleaning tools. You can get a squeegee to make the job easier on your hands. You might also want some gloves to keep your hands dry. You can also invest in window cleaning equipment that will help you reach those windows on the second floor.
Wash Windows with a Mild Solution First: Now that you have your window cleaning supplies ready, start by hosing down the window and frame. Wash it using a mild solution. Soap and water works just fine. Use a soft cloth and rinse off your sudsy windows.
Clean Windows with a Stronger Solution: After rinsing the windows with a mild solution, it's time to use something stronger. You can use a commercial window cleaning solution made for glass, or you can try something homemade. One of the more common window cleaning solutions involves 2 cups of water, ¼ cup of vinegar and ½ teaspoon of soap. Put the solution in a spray bottle and apply to your windows. Clean the solution off with soft paper towels, cloths or a squeegee.
Newspaper Trick: You'll notice the solution runs down the window right away. Curse you gravity! The solution may not stay on the window long enough to dissolve the tougher deposits of minerals or bird droppings. You can try soaking a newspaper in vinegar and water. Use the newspaper to gently scrub the window. The newspaper has a non-abrasive grit that can get rid of the stuck on deposits without damaging the glass.
Don'ts
Don't Use Solvents: Avoid solutions that have grease remover, bleach or strong soaps. These can damage your window and cause more harm than good.
Don't use Abrasive Materials: You might think you need the steel wool or rough sponge to get out those pesky sun-baked window stains, but these abrasive materials can damage your windows.
Don't be Over-Aggressive: A light touch and a good solution is all you need to keep your windows clear and shiny. It's tempting to rev up that power washer, but that's like using an axe when you only need a scalpel.
Protect your windows to keep heating and cooling costs down. Keep your home happy and bright. Avoid long-term damage by cleaning your windows regularly.
As you can see, it can be a lot of work. And it may take time that you don't have.
