The hydrangeas leaves don’t often turn yellow, but gardeners sometimes have to deal with this problem. Yellowing leaves on the shrub can signify that you are not following the rules for growing. Sometimes, you may try to change the maintenance requirements randomly. But you make it worse doing it that way.
Most of the time, yellow leaves on hydrangeas are caused by fungal diseases, a lack of nitrogen, or chlorosis, which happens when the plant doesn’t have enough iron. To stop the leaves from turning yellow, water them deeply twice or three times a week. Then, to keep the hydrangea full and green, feed it Epsom salt and nitrogen-rich fertilizer.
How To Identify The Issue With Your Hydrangea in The Right Way
To correct the situation, you must first identify the source of the plant’s distress and then act.
There are three types of hydrangea leaves yellowing:
- Leaves turn yellow completely and fall off
- Leaves turn yellow, and the veins are green
- Only the edges of the leaves become yellow
- Leaves turn yellow During Flowering
1- Leaves Turn Yellow Completely and Fall Off
With this symptom, you should pay attention to several factors:
- waterlogged soil;
- low temperature and cold air;
- lack of minerals during the formation of buds and flowering.
Reduce watering if the lower leaves on your hydrangea have turned yellow and the soil is already quite soggy. You might have forgotten to make a drainage layer to get rid of extra water when planted in the pot or soil.
Sometimes hydrangea’s yellow leaves at the bottom may be due to the normal aging process. The leaves at the bottom will turn yellow with time and fall off.
2- Hydrangea Yellow Leaves Green Veins
Hydrangea leaf plates frequently turn yellow or even white, but the veins on the leaves remain green. This is iron chlorosis, and it primarily affects the apical shoots.
The cause of this disorder is a severe lack of iron in the soil, which disrupts chlorophyll formation in the leaves, reducing photosynthesis activity.
Photosynthesis is a critical biological process that is the foundation of plant life. You can help your hydrangea leaves by adding chelated iron to the soil with water.
3- Only the Edges of the Leaf Become Yellow
If hydrangeas don’t get enough magnesium or sulfur, their leaves will also turn yellow and dry out around the edges, though the symptoms will be slightly different.
For example, magnesium chlorosis, caused by a deficiency of this trace element in the soil, causes the plant’s lower leaves to turn yellow, dry out, and fall off.
Chlorosis makes it more likely that a hydrangea won’t survive the winter, and it can even destroy it.
Sulfur chlorosis occurs when there is a lack of sulfur. It causes the leaves to develop yellow or whitish streaks.
There are other types of chlorosis: calcium, zinc, and nitrogen. It all depends on what microelement is missing in the soil. To avoid such problems, you need to feed the plant periodically.
4- Leaves Turn Yellow During Flowering
If the leaves have turned yellow during a blooming period, more nutrition is probably needed since flowering is energy demanding and requires a lot of effort.
How to Fix Hydrangea Yellow Leaves
I already listed the reasons for hydrangea leaves turning yellow. Now, Let’s discuss why the hydrangea leaves turn yellow and how to deal with it.
1-Deficiency of Nutrients And Minerals After Flowering
Iron deficiency is one of the most common reasons hydrangea leaves turn yellow. You can easily identify this nutrient deficiency by observing the color change of the leaves.
Iron is one of the most important catalysts for chlorophyll formation; if it is lacking, the leaves will lose the vigor of green color.
So, when your hydrangea turns yellow from the edges and the vein remains green, then this is a clear indication that the plant lacks iron.
From early spring to mid-summer, it needs regular feeding. Before flowing in spring, the plant needs more nutrients than normal time.
The deficiency of nutrients, in particular nitrogen and iron, is threatening:
- Incomplete formation of inflorescences;
- Yellowing of the leaf tips;
- Drying out and falling of leafy greenery.
The solution to the problem is the timely application of iron-rich fertilizers. For example, iron chelates, blood meal, manure, and compost contain a good level of iron for plants.
2- Lack of light or Excessive Sun Exposure
Hydrangea is a light-loving species but does not tolerate direct sunlight. Incorrect placement of the plant pot can lead to the yellowing of the leaves and the complete drying of the plant.
When choosing a location, you must consider that it doesn’t get direct sunlight.
UV radiation is the most dangerous between 12 and 15 hours of the time period.
The best place to land is where sunlight hits in the afternoon for no more than 6 hours.
Otherwise, the shrub can get a serious sunburn. Semi-transparent stains may appear on the leaves, turning yellow and dry.
Hydrangea also doesn’t like dark areas. It doesn’t feel good where it is darkened by tall plants with a lush crown or other bigger shrubs.
3- Water Logging Condition
Another reason why hydrangeas have yellow leaves is the wrong watering. Hydrangeas are water-loving plants but will not grow in wetlands.
The root part begins to rot due to the constant dampness, and over time the plant dies. In this case, you should stop watering or reduce the frequency.
You can easily protect the shrub from water logging conditions. Make a drainage layer of stones or broken bricks at the bottom of the pot before planting or while transplanting.
You have to water hydrangeas systematically. The frequency of watering depends directly on external factors. If the topsoil layer is dry, you should moisten it.
I have written a separate article on how to save over watered hydrangea. In this article, I have described step by step process to save your hydrangea.
4- Soil Dryness
If the ground underneath the plant is constantly dry, the leaves will eventually turn yellow and fall off.
In the initial stage, you will see yellowness appearing at the tips and edges of the leaf. Then it begins to twist. So, what should you do to save your plant? Let’s find out.
You should not allow the soil substrate to dry out. Irrigate your plant with warm water twice a day. Use mulching to retain the soil moisture for a longer time.
For your information!
You can use Shredded conifers, cones, wood chips for mulch.
Plant your outdoor garden hydrangeas away from the trees; proximity can damage the shrub. It will not have enough water for life and growth and will start to dry out.
5- Drafts, Cold Winds and Temperature Changes
Hydrangea feels good in an area with no strong wind, for example, near a wall or fence. Because drafts hurt the plant. Leaves begin to turn yellow and dry over time.
In combination with low temperatures, the effect is accelerated several times, the plant dies faster.
The optimum temperature within the home for growing hydrangeas is +22°C (71.6°F).
If you raise this threshold, the plates will turn pale and yellow. This plant can not sustain sharp changes in the external environment.
Just for the record!
You should grow the outdoor species in the garden near the fence or against a wall. This will protect them from wind and drafts.
Drafts in hydrangeas reduce immunity and lead to diseases. Keep this plant in cool rooms for the whole fall-winter period.
In this period, the optimum temperature is +8°C (46.4°F). After hibernation, you can return the hydrangea to its previous glory. Here are some practical ways of reviving your hydrangea after winter.
6- Soil Depletion
A common reason hydrangea leaves turn yellow is the soil’s lack of trace elements. Due to the lack of nutrients, the plant’s immune system undergoes serious attacks.
You should regularly fertilize the potting soil with complex mineral fertilizers. Don’t forget to apply fertilizer at the time of planting. The soil should be suitable for acidity. The suitable range for hydrangeas is pH 5.5 and 6.5.
Make sure the soil is fertile. It should consist of two parts: the earth and humus, one part of peat and sand.
It would be great if you could add some decomposed manure. Before the arrival of spring, fertilize the hydrangeas soil with urea fertilizer.
During the period of budding and flowering, you must feed your hydrangeas at least 3 times.
The nutrients in pot soil deplete over time. That’s why you have to recharge it every year.
You can do this by applying fertilizers to the soil. When the plant flowers or new leaves are born, it needs a lot of nutrients.
So if you do not supply nutrients, it may not flower next year. The fertilizer solution should contain potassium sulfide and superphosphate components.
7- Low Soil Acidity
Another reason why hydrangea leaves turn yellow is the alkaline substrate. If the pH is not normal, the leaves turn yellow.
All hydrangeas feel great in acidic soil. Therefore, before planting, you should test to determine this parameter. Because leaves may turn yellow due to low acidity.
The shrub has healthy and strong shoots. As you already know, this plant grows well in the soil with a pH of 5.5–6.5.
If your potting soil is not acidic, you can easily correct the soil’s pH.
To acidify the soil, occasionally water it with acetic or citric acid (4-5 ml per 1/4 gallon of water). You can use mulching to retain the soil moisture.
8- Diseases of Hydrangea
- Chlorosis: Your hydrangea leaf colors may change due to chlorosis infection. The disease appears as follows: the leaf plate turns yellow with bright green veins. To help the plant eliminate this disease, you must prepare a solution consisting of 30 ml of potassium nitrate and 2.5 gallons of water. Then, water the shrub one time a week for 30 days.
- Gray rot: If the plant leaves begin to blacken, curl, and crumble over time. Then your hydrangea has become infected with gray rot. To combat this fungal disease, you need to use a 1% solution of the Bordeaux mixture.
9- Root System Damage
If the hydrangea turns yellow in early summer after an improper transplanting. In that case, damage to the roots has not healed, and the plant is losing its decorative appearance.
The root system of hydrangea is quite weak. It can easily be damaged during planting and transplantation. Small wounds can lead to plant infection and drying out of its leaf system.
Pruning root systems will result in stunted growth and various diseases of hydrangeas.
Therefore, you should treat the root with charcoal before transplanting. This will help the root eliminate any fungal or bacterial infection.
Why Do Different Species of Hydrangeas Leaves Turn Yellow?
Each species of hydrangea requires certain care and special growing conditions.
- Panicled hydrangea: Gradual yellowing of leaves in panicled hydrangea may be due to improper care. This type of shrub feels good in a temperate climate. The flowering period lasts almost the entire summer- from early June to early August.
- Bigleaf hydrangea: Large-leaved hydrangea is suitable not only for gardening but also for indoor gardens. Growing care, watering rules, and soil composition are almost the same as growing geraniums. It begins to bloom in the spring and pleases you with its inflorescence almost until the summer. The leaves in this variety of hydrangeas turn yellow, most often due to fungal infections.
- Tree hydrangea: This is a straightforward type of hydrangea. It leaves the turn yellow mainly due to care mistakes.
How to Apply Fertilizer When Hydrangea Leaves Turning Yellow
Nutrient deficiency is one of the main reasons for leaves turning yellow. So you have to supply proper nutrition to your hydrangea to save it from yellowing.
In the spring season, make a nitrogen-containing mixture to increase the green foliage.
In summer, choose a fertilizer with major nutrient elements like nitrogen, phosphorus, and potassium for rich flowering.
And finally, in the fall months, potassium-phosphorus composition prepares hydrangeas for wintering.
If the plant suffers from iron deficiency, water your hydrangea with Chelated Iron Solution.
Besides yellowing, there are some other possible leaf problems
Leaves Turn Pale (lighter)
Hydrangea leaves may turn pale due to infestation with powdery dew. If you do not remove the infected areas in time, the disease will spread quickly to the whole plant. In this case, you should consider applying a fungicide.
Leaves Become Black
If the leaves have dry black spots, the plant is watered with unsuitable water or exposed to direct sunlight. You can bring the shrub back to normal by changing the conditions.
Hydrangea leaves are twisted because they have been affected by harmful parasites. In this case, carry out a thorough inspection and emergency treatment with insecticides
How To Prevent Yellowing of Hydrangea Leaves
It is necessary to provide quality growing conditions to prevent the yellowing of your hydrangea plant. Here are some actionable tips to prevent the problem.
- Find a place for your hydrangea so that the delicate plant remains under diffused sunlight;
- It is important to control the level of soil moisture to prevent drying out or excessive moisture;
- Use settled water at room temperature for irrigation.
- In the rainy season, add wood ash under each bush of garden hydrangea – this will help the roots adapt to adverse conditions;
- Control the level of acidity and soil leaching;
- At the stage of active budding and flowering, maintain the health of the shrub with mixed fertilizers;
- Spray with 1% Bordeaux solution once a month. This will prevent fungal diseases and attacks by harmful insects.
- Systematically revive hydrangea by removing old and diseased stems.
Keeping your plants beautiful and healthy is not at all difficult. The main thing is to properly and timely care for the plant and not to neglect preventive measures. You have to take measures to avoid various diseases and infections.