If you don't want to use chemical cleaner right away, you should try potato peelings first. Potato water is also great to use in the household.
Some people swear by the cleaning power of potatoes when it comes to limescale stains - because they contain a high proportion of starch. Not only kitchen surfaces, but also mirrors should be made to shine streak-free using potato peels. A few squirts of dishwashing liquid are enough to dissolve the grease in the sink. In spring it is also time to thoroughly remove stains from the windows.