Yellowing leaves can be a sign the herb plant lacks sufficient nutrients, particularly nitrogen. Start giving the herb a balanced liquid plant food, such as 14-14-14, once a week when you normally water the plant. Dilute the fertilizer to half strength to prevent fertilizer burn, which can also cause yellow leaves.Click to see full answer. Simply so, why are my mint plant leaves turning yellow?Although it likes moist soil, overwatering leads to disease. You should give it 1 or 2 inches of water every week, depending on the temperature and soil. Proper sunlight and watering will prevent or minimize most diseases, but there are several reasons why your plants might develop yellow leaves.Likewise, can yellow leaves turn green again? Diagnosis: If the leaves are turning yellow — almost jaundice-looking — and the center stalk is turning brown and getting a little soft, chances are you might be overwatering your plant. Lastly, remove yellow leaves, as they will not turn vibrant green again — and don’t worry, it’s all for the best. Accordingly, why are my herbs turning yellow? Water and Soil Problems Yellow leaves on herb plants may also indicate a lack of water or nutrients, causing the plants to shed some of their leaves, which typically turn yellow before falling. A plant in this condition should be repotted into a larger container, loosening the root ball and adding fresh potting soil.What nutrient deficiency causes yellow leaves?The most common nutrient problem associated with chlorosis is lack of iron, but yellowing may also be caused by manganese, zinc, or nitrogen deficiencies. According to Schuster one way to separate iron deficiency from other deficiencies is to determine what foliage turned yellow first.