Don't fret! Yellowing geranium leaves is usually just a sign that you've been a little too generous with the water. However, there might be a few different reasons why the leaves have turned yellow. Nutrient deficiencies and lack of sunlight can also cause the leaves to turn yellow, so it's good to keep an eye on these things. But don't fret! The most common culprit is simply overwatering. You might want to try watering less often.