Before applying anything other than water to any plant which is expressing difficulties, make sure the problem isn't insufficient water. All "fertilizers" and such are salts, and the only way they can enter the plant's cells is to remove water from the plant and replace it with the salts. If your plant is ailing because of a lack of water (due to not enough supplied; drainage, rot, damage, etc. to the roots; too much heat to the root area due to the pot over heating, etc.), and you "fertilize" it, you can easily damage or kill the plant. A safe rule of thumb is not to apply anything other than water until you see the plant appear to improve, such as new growth beginning. Then, go with a light feeding. When you are sick, you don't eat a full meal, but start with smaller portions until you feel your strenght return. Your plants appreciate similar treatment.

While the symptoms may resemble a nutrient or micro nutrient deficiency, those effects are usually slow to appear and progress. A lack of water; transplant shock; an extreme change in conditions such as a large increase or decrease in heat or light; an over application of fertilizer, or applying when the plant is too dry, usually cause faster, more extreme symptoms. For those which come on quickly, only using water until they improve is often the safest bet.