Why hydrangea leaves turning yellow

Yellow hydrangea leaves are most likely caused by a deficiency in iron or magnesium or both. Most hydrangea plants are deciduous, meaning they lose their leaves annually, usually in autumn and winter. Hydrangea leaves will typically turn yellow, brown or even an off-purple colour as winter approaches, and this is all normal.

The hydrangea leaves shown below are showing early signs of chlorosis:. Tell-tale signs of this are:. The photo below shows a comparison between a healthy green leaf and a smaller yellow leaf, note the green veins in the smaller leaf:.

Another photo showing obvious chlorosis on a new hydrangea leaf:. The leaf shown below was taken from a healthy hydrangea; note the uniform green colour across the leaf and veins. If your hydrangea plant has yellow leaves and green veins on new growth only — this is iron deficiency, of which there are several causes so keep reading. If the leaves are yellow with green veins but only on older established leaves — this is magnesium deficiency, and there are several causes of this too.

I recommend the product below, but most garden centres will stock something similar. Formulated specifically to bring yellowing leaves back to full health, sequestered iron from Doff is fast-acting and can even be sprayed onto the leaves to speed up absorption.

Here are the most common causes of iron deficiency , which leads to yellow leaves with green veins on new growth:. Also, excessive watering of pots and containers will flush out the iron, compounding the problem. Lack of drainage — Another common cause of yellow hydrangea leaves is lack of drainage; while rarely an issue in most sunny borders, it affects plants grown in pots; you should make sure the pot has sufficient drainage holes.

Improper fertilisation — Certain minerals such as manganese, copper, zinc, calcium and phosphorus, can, when used in excess, prevent the plant from uptaking iron. Poor soil — Magnesium deficiencies often occur in plants grown in sandy, light soils. Mixing in a good quality multi-purpose compost should help.

Too much potassium — Fertilisers with a high potassium concentration such as tomato feed can cause problems with magnesium uptake as the hydrangea will prioritise the potassium. The soil or compost should be slightly moist but not waterlogged and certainly not bone dry.

Yellow hydrangea leaves can be caused by several issues, the most common being:. All of the above can lead to deficiencies, and while iron or magnesium supplements solve the problem in the short term, the underlying cause should be addressed. In addition to these symptoms, keeping the plant too wet can lead to root rot and even death.

If a plant has been allowed to dry out, the first step to recovery is to thoroughly water the entire root ball. If it is still in a pot, try setting the plant in a tub of water up to the rim until the dry roots have been completely soaked.

Then allow the hydrangea to drain freely. However, it must be remembered that the roots are damaged, and they will be unable to deal with soil that it is too wet. So, allow time between each watering for the soil to dry out slightly and for the roots to regenerate. Hydrangeas growing in a pot or newly planted in the ground have roots that are especially vulnerable to strong applications of fertilizer.

When one observes yellowing and browning leaf edges and leaf tips a day or two after the plant has been fertilized, the roots may have been burned. Aluminum sulfate, which is sometimes added to the soil to change the color of hydrangea blooms, also can cause root damage if applied too liberally. Thoroughly flush the hydrangea soil with water whether it is in a pot or in the ground. This should remove most of the salts from the soil. Then do not water the hydrangea for a day or two until the soil is slightly dry on the surface.

Then water the plant as usual. If the hydrangea is grown in a container, make sure the water drains out the bottom of the pot after each watering. This will keep the salts flushed out on a regular basis this applies to houseplants, too. After root-burn, do not fertilize again until the plant appears healthy, suggesting that it has developed a well-established root system.

Diagnosing this is relatively easy as hydrangea rust looks different than most other leaf problems. This is when the leaves develop orange spots on the underside of the leaves. This is a fungal disease where the spores spread in water.

The leaves will eventually turn yellow or brown and fall off. Causal agent: Pucciniastrum hydrangeae. As mentioned above, this disease will spread due to water splashing on the leaves. This commonly happens when watering the plants. So when watering, be sure to spray the water towards the base of the plant while keeping the leaves above as dry as possible. That will help prevent the rust from spreading.

If the problem is severe, you may use a fungicide designed to treat rust. This is our favorite one below. This is another common problem that is easy to identify. Powdery mildew on hydrangeas will often look like a pale gray, powdery coating on the leaves. This is also a fungus that spread through spores. This typically happens during periods with hot days and cool nights.

The large swings in temperatures help spread this disease. Causal agents: Golovinomyces orontii formerly Erysiphe polygoni , Erysiphe poeltii, Microsphaera friesii, Oidium hortensiae. The best way to treat this fungus is to remove any leaves or parts of the plant that have been infected. Unless the problem is so severe that you would have to remove entire sections of the plant.

When watering, be sure to water the base of the plant. That will help keep the leaves dry and further spreading the fungus. Also, water in the morning so the leaves can dry out during the day and before the temperature drops at night.

Iron deficiency in hydrangea is characterized by the following:. Such a disorder occurs when you water the plants with hard water. The good news is that iron deficiency can be fixed easily by feeding the plant with some potent iron chelates in the pot.

The signs of nitrogen deficiency in hydrangea include lower, older leaves turning light yellow and the entire plant growing slower than usual. Nitrogen deficiency is easy to fix, but you need to determine why the nutrient is not adequate. For example, if you fertilize your plant with a good indoor plant fertilizer yet the leaves are turning yellow, it is possible that the nutrients are being flushed out of the pot possibly due to overwatering and drainage holes being too big.

We all know the hydrangea as this amazing plant with beautiful flowers. That is because it is not known for its foliage; rather, it is the blossoms people are interested in. Apart from preferring well-draining soil and with plenty of moisture in the root zone, hydrangeas like partial sun. To fix the yellowing leaf problem, place your hydrangea plants where they receive full morning sun and stay in the shade the entire afternoon.

Keep in mind the scorching midday and afternoon sun can cause hydrangea leaves to lose water excessively, droop, wilt, and suffer from curling leaves. If the problem is the lack of light or excessive lighting, you should place it in a place where it will receive the afternoon sun.

You should note that the UV radiation is harmful to the plant when it receives sunlight for 11 to 15 hours. The spot that you pick should enable the plant to receive 6 hours of the afternoon sun. If not, the plant could get a severe sunburn. You should also be aware that the hydrangea plant does not thrive in dark places either. The plant will not grow well if it is overshadowed by other tall plants or any other big shrub.

If so, supplement the deficient iron using iron chelates. When feeding the plant to fix iron deficiency and stop the yellowing, do not overwater the plant. Overwatering will flush out the nutrients and leave the soil in the pot with inadequate nutrients to feed hydrangeas for healthy leaves and flowers.

If the problem is dry soil, the leaves will turn yellow and fall off. So what should you do in this case? If the problem is wrong watering, you should minimize the frequency in which you water the plant. You could even stop watering the plant altogether if the place you have planted the hydrangea is constantly wet. You can also protect the hydrangea plant from being water-logged by using a drainage layer made of either stone or broken bricks at the bottom of the bucket or pot.

The layers should be put before planting or when transplanting. If you ever find yourself in a situation where you overwater a hydrangea plant, do not panic. Just follow these guidelines, and everything will be fine. If the problem is a lack of nutrients, you should fertilize the soil in which the hydrangea plants are growing in.

Add mineral fertilizers to the soil, and do not forget to add manure during planting. An iron-rich fertilizer such as Milorganite is great to help get rid of iron chlorosis and signs of nitrogen deficiency. If the problem is low soil acidity, the leaves will turn yellow.