There's a clue there--SOMEwhere:
like you water it and it "perks up;" you don't water it and it wilts.

Let us cogitate upon't ....

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After sufficient water is supplied and the entire plant "perks up" THEN fertilize (GENTLY); NEVER stimulate an ailing individual.

I think you mistook my point. I tried to water it when it was wilty but that seemed to cause the leaves to turn white and brown. Then the next day it wilted again after it showed me that watering it was not such a good idea.

I haven't actually added fertilizer yet. I read on line that it needs both acidic and alkaline soil which is confusing to me. Should I use acidic or alkaline fertilizer then?

Hi
Sounds like your potting mix is breaking down?? Try repotting in next larger pot with a good mix.
I'd bet you have dry spots in the mix.
gary

Scheffs need good drainage. They will drop leaves if overwatered (and if underwatered!) Wait until the soil is quite dry in the top several inches, then water, let drain and let dry out again. Repotting sounds like a good idea - try adding some perlite to your soil for extra drainage.

I've only grown scheffs indoors - some types of plants (like my tropical hibiscus and bananas) will wilt in the hot afternoon sun, even if the soil is damp, because they just can't get the water from the roots to the leaves fast enough in the heat. They perk up again in the evening when it cools off. Perhaps this is happening with you?

I donÂt know where you are in CA, but if you are in Southern CA, it sounds like you need a bigger pot. The heat dries the plants out so fast overwatering is not an issue. The intense sun burns the leaves & they will turn white. If they are wilting & respond to water, they need to be moved to a cooler location, put in a bigger pot, or watered more. Good soil is important, but they will tolerate compact soil during this high heat period. I have 4 tree size Schlefferas as well as various small varieties & that is what I am experiencing. I do keep the variegated ones in the shade.
If you are not in a high heat zone, then the above comments probably apply.