I have a little apple sapling that I planted using a seed from an apple at the super market. I live in Auckland, New Zealand and my apple sapling is about 10 cm (4 in) tall. Recently it became very limp. I tried giving it more water, less water; more sun, less sun. I've kept it indoors and outdoors in both the shade and the sun. None of these things have improved its condition. What should I do?
Since your apple tree seedling doesn't respond to changes in watering, and you're not describing an infestation of the leaves, then it's most likely you have a root problem. Suggest you remove the seedling from the pot and see if the roots are rotting from previous over watering or an infection.