Like many nutrient deficiencies, a lack of nitrogen shows itself in hydrangea leaves. Nitrogen moves readily through plants. When leaves are affected by low nitrogen, the entire leaf turns pale yellow-green. This includes the leaf veins, which often stay green with other types of nutrient deficiencies.Click to see full answer. Likewise, why are my plant leaves turning light green?It’s the visible result of too little chlorophyll, the pigment used by plants to trap sunlight for photosynthesis. Since chlorophyll gives leaves their green color, an inadequate supply turns plants a pale green, yellow or yellowish white.Likewise, why are the leaves on my hydrangea turning yellow? yellowing on hydrangea leaves. Yellowing leaves usually indicates the plant is suffering from a nutrient deficiency. Over-watering can cause yellowing too, and it can exacerbate nutrient deficiencies as nutrients are flushed out of the soil. Most plants survive well with one good soaking per week around the root zone. In this manner, how do you turn hydrangea leaves dark green? If you suspect high pH is the culprit, try using acidic mulch such as pine needles over the plant’s root zone. Over time, acidic mulches will lower soil pH and help your hydrangea to produce more leaf-greening chlorophyll.How do you know if you are overwatering your plants? 5 Signs of Overwatering Wet and Wilting. It looks wilted, but the soil is wet. Brown Leaves. If the leaves turn brown and wilt, there is the possibility that you have been overwatering. Edema. The third sign that your plant has been overwatered is edema. Yellow Falling Leaves. Root Rot.