Why Your Hydrangea Leaves Are Turning Yellow And How To Fix It

Hydrangeas are beloved for their large, showy blooms and lush foliage. However, if you notice that the leaves on your hydrangea are turning yellow, it may indicate a problem. Yellow leaves can be caused by a variety of factors, including over-watering, under-watering, nutrient deficiencies, pests, or disease. In order to fix the problem and get your hydrangea back to its healthy, green state, it’s important to first identify the cause of the yellow leaves. Once you know the cause, you can take steps to address it and revive your hydrangea.

What Makes Hydrangea Leaves Turn Yellow?

 Nutrient Deficiencies

Nutrient deficiencies can cause hydrangea leaves to turn yellow in the following steps:

1. The plant is not getting the necessary nutrients from the soil to maintain healthy growth.
2. As a result, the leaves will start to turn yellow, indicating a lack of chlorophyll.
3. Without enough chlorophyll, the plant is not able to photosynthesize effectively, leading to stunted growth.
4. If the deficiency continues, the leaves will continue to yellow and may eventually drop off.
5. The overall health and appearance of the plant will deteriorate if the nutrient deficiency is not corrected.

To correct nutrient deficiencies, you can amend the soil with fertilizer, compost, or other organic matter to provide the necessary nutrients for the hydrangea to thrive. If the problem persists, you may consider taking a soil sample and sending it to a lab for testing to determine which nutrients are lacking and how much to add.

Iron Deficiency

Iron deficiency is a common cause of yellowing leaves in hydrangeas. It can be caused by a number of factors, including:

1. High pH soil: Hydrangeas prefer slightly acidic soil with a pH between 5.0 and 6.5, but if the pH is too high, the plant may struggle to absorb iron from the soil.
2. Over-watering: When the soil is too wet, the roots of the plant can suffocate, which can lead to iron deficiency.
3. High levels of phosphorus: High levels of phosphorus in the soil can also prevent the plant from absorbing iron.
4. Iron chelates: Iron chelates are a form of iron that is easily absorbed by plants and can be added to the soil to correct an iron deficiency.
5. Foliar sprays: Iron can also be applied as a foliar spray directly on the leaves, which can help to quickly correct an iron deficiency.

To fix Iron deficiency, it’s best to lower the pH of the soil to the range of 5.0 to 6.5 by adding sulfur or Aluminum sulfate, using iron chelates, or applying a foliar spray of iron. It’s also important to be mindful of the watering and fertilization schedule to avoid over-watering or applying too much phosphorus.

Nitrogen Deficiency

A Nitrogen deficiency in hydrangeas can cause the leaves to turn yellow and the overall growth to become stunted. It can be caused by several factors, including:

1. Soil with low nitrogen levels: Nitrogen is an essential nutrient for plant growth, and if the soil lacks it, the plant will struggle to maintain healthy growth.
2. Overuse of pesticides: Some pesticides can disrupt the nitrogen-fixing bacteria in the soil, leading to nitrogen deficiency.
3. Overuse of high-phosphorus fertilizers: High levels of phosphorus in the soil can also prevent the plant from absorbing nitrogen.
4. Compaction of soil: If soil is compacted, it can limit the access of plant roots to the available Nitrogen.

To fix Nitrogen deficiency, you can amend the soil with fertilizer that contains high levels of nitrogen or use Nitrogen-rich organic matter such as blood meal or chicken manure. It’s also important to avoid the overuse of pesticides and high-phosphorus fertilizers and to practice good soil management to avoid soil compaction.

Diseases That Affect Hydrangea Plants

Magnesium Deficiency

Magnesium deficiency in hydrangeas can cause the leaves to turn yellow between the leaf veins and the margins of the leaf to become brown. It can be caused by several factors, including:

1. Soil with low Magnesium levels: Magnesium is an essential nutrient for plant growth, and if the soil lacks it, the plant will struggle to maintain healthy growth.
2. High soil pH: Magnesium is less available to plants at higher pH levels and can lead to a deficiency.
3. Overuse of potassium-rich fertilizers: High levels of potassium in the soil can also prevent the plant from absorbing magnesium.
4. Poor drainage: Hydrangeas prefer well-drained soil, and if the soil is consistently waterlogged, magnesium can be leached out of the soil, causing a deficiency.

To fix Magnesium deficiency, you can amend the soil with fertilizer that contains high levels of magnesium, such as Epsom salt. You can also lower the pH of the soil to make Magnesium more available to the plant. It’s also important to avoid the overuse of potassium-rich fertilizers and to practice good drainage in the garden.

Rot Root

Root rot is a condition that occurs when the roots of a plant are damaged or killed by disease-causing organisms, such as fungi or bacteria. It can be caused by several factors, including:

1. Over-watering: When the soil is consistently too wet, the roots of the plant can suffocate and become more susceptible to disease.
2. Poor drainage: If the soil does not drain well, the roots can become waterlogged, leading to root rot.
3. Planting in heavy clay soils: Clay soils tend to retain water, leading to poor drainage and an increased risk of root rot.
4. High humidity: High humidity can create an ideal environment for disease-causing organisms to thrive.

Symptoms of root rot include yellowing leaves, wilting, stunted growth, and a mushy or rotten smell when the soil is disturbed. To fix root rot, it’s essential to improve drainage and avoid over-watering. Remove the affected plant, and if possible, cut away all the affected roots, and replant the healthy parts of the plant in well-drained soil. It’s also important to maintain a proper watering schedule and to avoid overcrowding plants to promote good air circulation.

Hydrangea Mosaic Virus

Hydrangea mosaic virus (HMV) is a disease caused by a virus that can affect hydrangeas and other plants in the same family. Symptoms of HMV include:

1. Yellowing and mottling of leaves: The leaves may have a distinct yellow or light green pattern.
2. Stunted growth: The plant may be smaller and have fewer blooms than normal.
3. Distorted flowers: The flowers may be smaller and misshapen.
4. Leaf curling: The leaves may curl or twist.
5. Reduced vigor: The plant may appear weak and less vigorous overall.

The virus is spread by aphids, and once a plant is infected, it is difficult to cure. The best way to prevent the spread of the virus is to control the population of aphids and to avoid planting near infected plants. Keep an eye on the plant for any signs of the virus, and if you suspect that your plant is infected, it is best to remove it to prevent the spread of the virus to other plants.

Tomato Ringspot Virus

Tomato ringspot virus (ToRSV) is a plant virus that affects tomato plants and other plants in the Solanaceae family. It is spread by several species of nematodes, which are small, soil-dwelling worms. Symptoms of ToRSV can vary depending on the stage of infection and the type of plant affected but may include:

1. Leaf mottling and yellowing: The leaves may have a distinct yellow or light green pattern.
2. Stunted growth: The plant may be smaller and have fewer blooms than normal.
3. Distorted or curled leaves: The leaves may be curled or twisted.
4. Reduced fruit production: The plant may produce fewer and smaller fruits.
5. Reduced vigor: The plant may appear weak and less vigorous overall.

Once a plant is infected with ToRSV, it is difficult to cure, and the best way to prevent the spread of the virus is to control the population of nematodes and avoid planting near infected plants. Also, it is important to use clean seeds and to use resistant varieties if they are available.

Watering Problems

Watering problems can cause various issues in hydrangeas, including yellow leaves. Over-watering and under-watering are the two most common issues:

1. Over-watering: When the soil stays too wet for too long, the roots of the hydrangea can suffocate, causing the leaves to turn yellow and the plant to become stunted. It’s important to let the soil dry out a bit between watering and to ensure that the drainage is good.
2. Under-watering: A lack of water can also cause the leaves to turn yellow, as the plant is unable to absorb the necessary nutrients to stay healthy. It’s important to keep an eye on the soil moisture and water the plant when the soil feels dry to the touch.

It’s also important to note that hydrangeas prefer consistent moisture and do not let the soil dry out completely or stay soggy for extended periods of time. It’s best to check the soil moisture regularly and adjust watering accordingly, making sure to provide enough water to keep the soil consistently moist but not waterlogged.

Wrong Lighting Conditions

Wrong lighting conditions can also cause yellow leaves in hydrangeas. Some common lighting-related issues include:

1. Too much sun: Hydrangeas prefer filtered or dappled sunlight and too much direct sun can cause the leaves to turn yellow and become scorched. It’s best to plant hydrangeas in a location that provides some shade during the hottest part of the day.
2. Not enough light: If a hydrangea is not getting enough light, it may become leggy, and the leaves may turn yellow. It’s important to provide the plant with enough light to allow for healthy growth.
3. Strong wind: Strong winds can cause the leaves of hydrangea to dry out, which can lead to the yellowing of the leaves.

To fix lighting-related issues, it’s best to monitor the lighting conditions in the area where the hydrangea is planted and make adjustments as needed. Move the plant to a location that provides the appropriate amount of light, whether it’s more or less. Additionally, you can also use shade cloth or other physical barriers to protect the plant from strong winds and excessive sun exposure.

Sudden Temperature Changes

Sudden temperature changes can cause stress on hydrangeas, which can lead to yellow leaves. Some common temperature-related issues include:

1. Frost damage: Hydrangeas are not frost-tolerant, and a sudden frost can damage the leaves and cause them to turn yellow.
2. Heat stress: When temperatures become too high, hydrangeas can become stressed, which can cause the leaves to turn yellow.
3. Rapid changes in temperature: Sudden changes in temperature, such as moving a plant from a warm location to a cool one, can cause stress on the plant and lead to yellow leaves.

To fix temperature-related issues, it’s important to protect the plant from frost by providing frost protection, such as covering the plant with frost cloth or moving it to a sheltered location when frost is expected. Also, it’s best to keep hydrangeas out of direct sunlight during hot summer days. And when moving plants, it’s best to give them time to adjust to the new environment by placing them in a shaded area for a few days before moving them to the final location.

Issues With The Soil’s pH

The pH of the soil can affect a plant’s ability to absorb the nutrients it needs, which can lead to yellow leaves in hydrangeas. Some common pH-related issues include:

1. Soil pH is too high: Hydrangeas prefer slightly acidic soil with a pH between 5.0 and 6.5, but if the pH is too high, the plant may struggle to absorb certain nutrients, such as iron, which can cause the leaves to turn yellow.
2. Soil pH is too low: If the soil pH is too low, the plant may struggle to absorb certain nutrients, such as phosphorus, which can cause the leaves to turn yellow.

To fix pH-related issues, it’s important to test the pH of the soil and adjust it as needed. To lower the pH, you can add sulfur or aluminum sulfate to the soil. To raise the pH, you can add lime to the soil. It’s also important to test the soil pH regularly and make adjustments as needed to maintain the appropriate pH range for the plant.

How To Prevent Hydrangea Leaves From Turning Yellow?

To prevent hydrangea leaves from turning yellow, it’s important to take the following steps:

1. Provide proper care: Make sure the plant is getting the right amount of water, sunlight, and nutrients. Monitor the soil moisture, and adjust the watering schedule accordingly. Keep an eye on the lighting conditions, and make adjustments as needed.
2. Use the right soil: Use well-draining soil that is rich in organic matter. Make sure the soil pH is within the range that hydrangeas prefer (5.0-6.5)
3. Fertilize regularly: Use a balanced fertilizer that is formulated for hydrangeas or other acid-loving plants. Follow the instructions on the fertilizer package and apply it at the appropriate time.
4. Control pests and diseases: Keep an eye out for signs of pests or diseases, and take action as soon as you notice them. Use appropriate pesticides or fungicides to control infestations, and practice good hygiene to prevent the spread of disease.
5. Avoid environmental stress: Hydrangeas are sensitive to environmental stress, such as sudden temperature changes, strong winds or harsh weather conditions, and too much direct sunlight. Try to protect the plant from these conditions when possible.

By following these steps, you can help ensure that your hydrangea stays healthy and lush with green leaves.

How to Save Overwatered Hydrangea?

To save an overwatered hydrangea, the following steps can be taken:

1. Stop watering: The first step is to stop watering the plant until the soil has a chance to dry out. This will allow the roots to breathe and recover.
2. Improve drainage: Make sure that the soil drains well, by amending it with compost or other organic matter, or by adding gravel or coarse sand to the bottom of the planting hole.
3. Remove affected soil: Carefully dig out the soil around the roots, and remove any soil that is waterlogged or appears to be rotting.
4. Trim-affected roots: Cut away any roots that appear to be black or mushy, as they are likely dead or dying.
5. Replant in well-draining soil: Replant the hydrangea in well-draining soil, making sure to provide good drainage and not to plant it too deeply.
6. Monitor the soil moisture: Be mindful of the soil moisture going forward, and adjust the watering schedule as needed to keep the soil consistently moist but not waterlogged.
7. Be patient: Hydrangeas are resilient plants, but it may take some time for the plant to recover from overwatering. Be patient and provide the plant with proper care and attention, and it should start to recover in time.

It’s important to keep in mind that overwatering can cause damage to the roots, and it may take some time for the hydrangea to recover. And also, in some cases, it may not recover, and it’s best to consider replacing the plant.

Should you Cut Off Yellow Leaves?

It is generally recommended to cut off yellow leaves on hydrangeas as they can drain energy from the plant and may indicate a problem that needs to be addressed. By removing the yellow leaves, the plant can redirect its energy to producing healthy new growth. However, it’s important to consider the cause of the yellowing leaves before cutting them off. If the yellowing is caused by a pest or disease, it’s best to address the underlying problem before pruning.

When cutting off yellow leaves, it’s important to use clean, sharp shears to make a clean cut as close to the stem as possible. If a large portion of the plant is affected, it’s best to remove the yellow leaves gradually over time instead of removing them all at once. It’s also important to not remove more than one-third of the plant at a time, as this can stress the plant and make it more susceptible to disease.

It’s also important to consider the time of the year, as cutting off the yellow leaves at the wrong time of the year may affect the blooming of the plant.

How Should You Apply Fertilizer When the Hydrangea Leaves are Yellow?

When applying fertilizer to a hydrangea with yellow leaves, it’s important to first determine the cause of the yellowing, as this can affect the type of fertilizer that should be used.

1. In case of nutrient deficiencies: if a soil test indicates a specific nutrient deficiency, such as iron or nitrogen, use a fertilizer that is formulated to address that deficiency. For example, if the soil test shows a lack of Iron, a fertilizer with Iron chelate can be used.
2. In case of pH issues: if the soil pH is too high or low, adjust the pH before fertilizing. This can be done by adding sulfur to lower the pH or lime to raise it. Once the pH has been adjusted, use a balanced fertilizer that is formulated for acid-loving plants.
3. In case of over-watering or root rot: if the yellowing is caused by over-watering or root rot, it’s best to hold off on fertilizing until the plant has had a chance to recover. Instead, focus on improving drainage and allowing the soil to dry out before watering again.

When applying fertilizer, always follow the instructions on the package, as over-fertilization can burn the roots and make the yellow leaves problem worse. It’s also important to water the plant well before and after fertilizing to help the nutrients reach the roots.

It’s always a good idea to check the soil pH and nutrient levels before fertilizing, as this will help determine the right type of fertilizer to use and the right amount to apply.

Final Words on Why Hydrangea Leaves Turn Yellow

In conclusion, yellow leaves in hydrangeas can be caused by a variety of factors, including nutrient deficiencies, root rot, viruses, watering problems, wrong lighting conditions, sudden temperature changes, and issues with the soil’s pH.

To prevent yellow leaves, it’s important to provide proper care, use the right soil, fertilize regularly, control pests and diseases, and avoid environmental stress. If a hydrangea is already showing yellow leaves, it’s important to determine the cause and take appropriate action, such as adjusting the watering schedule, improving soil drainage, or adjusting the soil’s pH.

In some cases, yellow leaves may be a sign of a more serious problem, and the plant may not recover, in which case it’s best to replace the plant.