Hydrangea leaves turn yellow due to overwatering, too much direct sunlight, or nutrient deficiency. To fix the yellow leaves, move the plant to a shaded area and drain excess water from the pot. Feed the plant with an iron supplement and nitrogen fertilizer to keep leaves green and healthy.

What to do when leaves are turning yellow?

If you have a plant that has yellow leaves, check the soil in the pot to see if the soil is dry. If you believe that the problem is due to under watering, water the plant more often and consider letting the pot sit on a dish to recollect any water that has overflowed, so that the roots can absorb the extra water.

Why is my hydrangea leaves going yellow?

Nitrogen deficiency

If you noticed that older leaves on your hydrangea have started to turn yellow it could be a problem with nitrogen. The simplest cure is to add ammonium sulfate to the soil. ... Continue to water as you normally would and this will help to increase the amount of nitrogen in the soil.