How beautiful hydrangeas are! I wish there were more of this beauty around and that there were no problems with them. Unfortunately, problems with hydrangeas occur regularly and today we will discuss probably the most common one.
Nutrient deficiency, overwatering, scorching sun, or disease are the most common causes of hydrangea leaves turning yellow. To fix yellow leaves, water the hydrangea when the soil is 2 inches dry, feed it at least twice a year with iron fertilizer, and make sure the substrate is slightly acidic. Also, place the hydrangea in the semi-shade and spray with a fungicide to prevent the leaves from turning yellow.
|Why do hydrangea leaves turning yellow?||Symptoms||How to fix it|
|Overwatering||Uniform yellowing of the entire leaf area.||Stop watering and allow the soil to dry slightly. Repot the hydrangea in well-drained soil. Determine an optimal watering schedule.|
|Chlorosis||Yellow leaves with green veins.||Acidify your soil to a pH of 5.5-6.5. Apply iron chelate to bring back the green color of the leaves.|
|Underwatering||Yellowing and dropping of leaves.||Keep the soil around the hydrangeas slightly moist. The soil should not dry out more than two inches. Mulch the hydrangeas.|
|Excessive sunlight||Yellowing of the leaves. Leaf scorch.||Transplant the hydrangea to a place with early sun and afternoon shade. Increase watering slightly.|
|Nutrient deficiency||First, the leaves turn pale green and then turn yellow.||Check the pH of the soil, it should not be higher than 6.7. Apply a slow-release fertilizer. Improve the soil with compost.|
|Diseases||Yellow leaves with brown or black spots.||Provide hydrangeas with enough light and good air circulation. Spray the leaves with an aqueous solution of fungicide.|
|An abrupt drop in temperature||Large yellow spots on the leaves.||Cover hydrangeas for the duration of cold weather. Give additional liquid fertilizer for recovery.|
|Root issues||Yellowing and falling leaves.||Transplant the hydrangea into well-drained soil. Shade the hydrangea for a while.|
Nutrient deficiency in the ground is often the cause of yellowing leaves, not only hydrangeas but also many other plants. This is primarily due to a lack of nitrogen. In this case, the leaves first lose their bright green color and become pale, and after a while, they turn yellow. Mature leaves are the most susceptible. It is also possible that some of the leaves will dry out.
A lack of trace elements does not always indicate soil depletion. As I have already mentioned, a high pH of the soil prevents the plant from receiving nutrients. So first you should check the pH of your soil and if it is above 6.7 then you need to acidify it. You can read how to do this in the Chlorosis section above.
The next step is to feed the hydrangeas. These plants need a relatively large amount of fertilizer because their abundant flowering requires a lot of energy. I usually fertilize my hydrangeas twice a year. The first time I fertilize in early spring when the hydrangea has not yet begun to unfurl its leaves. The second time is after flowering when the flower heads are wilted.
I use slow-release pellets with a balanced ratio of Nitrogen, Phosphorous, and Potassium. The amount of fertilizer depends on the size and type of hydrangea. Manufacturers usually provide detailed instructions on how to use their products.
You also need to amend your soil with compost before planting. I have written about this before. This type of organic fertilizer will give the plant extra energy.
Too much water can cause hydrangea leaves to turn yellow
The first most common cause of hydrangea foliage yellowing is too much water. This can happen for a variety of reasons, such as improperly set automatic watering or too much rain. As a result, the hydrangea roots are left in the mud for a long time, which leads to their malfunctioning and the yellowing of the leaves. If you do nothing, the hydrangea may die.
The first thing to do is to stop watering. Hydrangeas are moisture-loving plants, but they are not lotuses and will not grow in water. If the soil is too wet, allow it to dry out slightly and then start determining the amount of water by trial and error.
You have to find out what type of hydrangea you have because a mature Hydrangea Panicle hydrangea in the sun needs more water than a Hydrangea macrophylla in the half-shade. In general, hydrangeas need no more water than once every 5 to 10 days during dry weather, but if it is raining then they do not need to be watered at all.
Also, pay attention to the soil. Clay soil holds moisture longer than sandy soil. Hydrangeas like moist but drained soil, so it should remain slightly moist but not soggy. If necessary, transplant the hydrangea to amended and drained soil.
As for hydrangeas that can grow in pots, such as Little Lime, this is simple. The soil in the pots should also be drained, the pots should have several drainage holes. Potted hydrangeas need to be watered a little more often than those that grow in the ground.
If the reason for the yellowing was overwatering and you have stopped watering, then in drained soil and with a proper watering schedule, the hydrangea will recover after a while.
Chlorosis is a plant disease in which the leaves turn yellow but the veins remain green. In late-stage chlorosis, the veins also turn yellow and the leaves die off.
Chlorosis is caused by a lack of iron and magnesium. It is iron that takes part in the creation of chlorophyll (green color), but when the iron is scarce, the leaves become less green.
But simply adding iron to the soil around the hydrangea will not solve the problem. The point is that for the plant to absorb iron from the soil it must be slightly acidic. Otherwise, the iron will not be available. At pH 7.0-7.5 most plants are not able to get iron and other trace elements from the soil.
The first thing you should do is check the pH of your soil. You can find soil testers in garden stores. Use it to find out what kind of soil you have and if the pH is above 6.7 you need to acidify your soil. You can lower the pH of the soil with acidifiers, such as the Espoma product. Hydrangeas need a soil pH of 5.5-6.5 to thrive.
You might also want to mulch the soil with compost. Compost is an organic soil acidifier, but it will take a year to work. There are also several other advantages to mulching with compost. Also in acidic soils, some varieties will have blue flowers, such as Endless Summer Hydrangea or Bloomstruck Hydrangea.
Next, you need to apply iron in a suitable form for your hydrangea. In this case, the iron chelate is best, which you can also easily find on the market.
Lack of water can also cause yellowing of hydrangea leaves. But apart from that, the leaves will also droop. If you do not water the hydrangea, the leaves will fall off and you may even lose the plant.
If your hydrangea is growing in sandy soil, you need to amend the soil. It is best to add good quality store-bought compost to the planting hole and mix it with the native soil. With such a substrate, you won’t have to water too often.
Next, you need to keep an eye on the moisture content of the soil. You can do this with a soil moisture meter or with your fingers. The soil around the hydrangea should not dry out more than 1 to 2 inches. In most cases, watering is needed in a severe drought. After a while, you can easily tell when your hydrangea needs water.
Separately, we must talk about newly planted and potted hydrangeas. Newly planted hydrangeas can easily turn yellow and drop their leaves. In this case, more frequent watering will not solve the problem completely. You should also shade your newly planted hydrangeas from the sun for a few weeks so that they can get used to their new location more easily.
Potted hydrangeas are more prone to underwatering. In extreme heat, the soil in the pots dries out very quickly and you may have to water every other day. Keep an eye on your potted hydrangeas and do not let the soil dry out.
Also, as I mentioned earlier, you may want to mulch your hydrangeas. This will ensure that the soil dries out slowly and reduces the frequency of watering.
Too much direct sunlight can also cause hydrangea foliage to yellow. This is called leaf scorch and can lead to large dry patches on the leaves.
This often happens when hydrangeas are improperly planted because different species and varieties have different sun requirements. Also, in different climates, the same amount of sunlight hours has a different effect on the plant.
Hydrangea paniculata varieties (Firelight, Quick Fire, Limelight, etc.) can withstand the direct sun for most of the day. Only in the south, they need shade in the afternoon. Mophead hydrangeas, on the other hand, are more susceptible to sun damage. Depending on the zone, they need 4 to 6 hours of direct sun, and the rest of the time they need shade.
If your hydrangea gets leaf scorch, you should transplant it to a darker location. Most hydrangeas will do best in early sun and afternoon shade. Also, if there is too much sun, you can slightly increase the frequency of watering. This will cause the plant to evaporate more moisture and possibly avoid sunburn.
You have to determine exactly how much sun your hydrangea needs because a lack of light can lead to a lack of blooming.
The next reason why hydrangea leaves turn yellow is a disease. This is primarily due to fungal diseases. Young leaves are most susceptible to the fungus in the spring. The fungus spores settle on the leaf surface and begin to develop. At first, they are not visible to the human eye, but the leaf gradually turns yellow and develops brown or black spots. If there are many spots, the foliage will die off.
Fungal diseases are caused by excessive humidity and high temperatures. These are ideal conditions for fungal growth. Also, insufficient air circulation around the hydrangea and a too shady location aggravate the problem.
To correct the yellowing of the leaves caused by disease, you first have to transplant the hydrangea into a location with the amount of light required for your type of hydrangea. Also, leave a gap of at least one foot between the hydrangea and other plants so that the air can move freely. Do not leave plant debris near the hydrangea to rot.
In most cases, these measures will be enough to avoid disease. But if the disease does occur, you will need to spray the leaves with a fungicide. There are many quality hydrangea fungicides on the market. Also, remove heavily diseased foliage.
An abrupt drop in temperature
A sudden drop in temperature can cause yellow spots on hydrangea leaves. During dormancy, this plant can tolerate quite a bit of frost, but when the leaf has already unfolded, low temperatures can harm it.
Late frosts will cause the leaves to wilt and die off, which is not what I am talking about right now. I’m talking about a change in temperature where it’s hot in the day and cold at night, like 41°F (5°C). As a result, the plant gets temperature stress and can respond with large yellow spots on the leaves.
To avoid this, you have to provide the hydrangea with the right conditions. Hydrangeas like temperatures in the 65-75°F range, so if the weather forecast says something chilly is coming, you might want to cover them up for the time being. You can use garden fabric designed to protect plants from frost for this purpose.
If temperature stress occurs don’t get upset; in most cases, hydrangeas will recover after a while. It’s best if you water Hydrangeas with liquid fertilizer once. This will give it a boost and make it heal faster.
Problems with the root system will definitely cause the leaves to yellow and fall off. Roots can become damaged during planting or transplanting. Also, some rodents can mutilate hydrangea roots. Finally, root rot is also a cause of leaf yellowing.
If transplanting has caused root damage, you will need to shade the plant for one to two months to alleviate the transplant shock. Also, water the hydrangea regularly but do not flood it. Some of the leaves will turn yellow and fall off, but the plant will remain alive.
If the roots of the hydrangea have been damaged by animals or rot, you need to dig the plant out and clean all the dead tissue. Then treat the wounds with fungicide and cover them with crushed wood ash. Then plant the hydrangea in drained soil and shade it completely for several months. Water it sparingly and keep the soil slightly moist. It can take a considerable amount of time to recover from such damage.
- Hydrangea leaves can turn yellow through too much or not enough water. To correct this, water the hydrangea when the soil is 1 to 2 inches dry.
- Hydrangeas can turn yellow through chlorosis. In this case, acidify the soil and fertilize the plant with a multi-purpose fertilizer.
- Hydrangea leaf yellowing can happen due to excessive sun exposure. Plant the hydrangea in a location with 6 hours of early sun and afternoon shade.
- Diseases can also cause yellowing of the leaves. Plant the hydrangea in well-drained soil and spray with fungicide.
- A sudden and sudden change in temperature will cause yellowing. Cover the hydrangea for the duration of the cold weather.