Hydrangea is amongst the most beautifully colorful bedding plants. Like most gardeners, you love seeing a healthy hydrangea garden arrayed in gorgeous blooms.
However, if you’ve started noticing the yellowing of some of your hydrangea leaves, you may wonder what’s wrong and how to fix it.
Causes of Hydrangea Leaves Turning Yellow
A range of issues could be the reason for the yellowing of hydrangea leaves. There is no one specific trigger for this anomaly. The issue might be deficiencies in the soil, diseases that affect hydrangea plants, watering problems, wrong lighting conditions, sudden temperature changes, or even issues with the soil pH.
1. Too Much Sunlight
The leaves may turn yellow if your hydrangeas are getting too much sunlight. Hydrangeas prefer partial shade, so if they’re in direct sunlight all day, it can cause the leaves to change color. Excessive sunlight also makes the leaves droop and go brown. The heat emitted from the sun affects the transmission of chlorophyll to aid photosynthesizing, hence the change of color of the leaves.
2. Not Enough Water
The leaves will also turn yellow if your plants aren’t getting enough water. When the soil is dry, the plant cannot feed as it should, causing dehydration. Over time, if this is not dealt with, your hydrangea will droop, the stems will begin to string out, and eventually, it will stunt its growth.
3. Soil Issues
Yellowing leaves can also signify soil problems, such as an imbalance of nutrients or too much salt buildup.
4. Pest Problems
Pests can also cause hydrangea leaves to turn yellow and eventually drop off the plant entirely. Common pests that affect hydrangea include aphids, scales, or mites—all these pests feed off the plant’s sap. Plant sap carries nutrients from the soil and distributes them to the plant leaves, so obstructing this process will cause the plant to wilt, become stunted, and die eventually.
5. Disease Problems
Diseases can also cause hydrangea leaves to discolor and fall off the plant. Common diseases include powdery mildew, leaf spot, hydrangea mosaic virus, tomato ring spot virus, and root rot. Root rot occurs when the soil drains poorly, or you have been overwatering your plant. The tomato ring spot virus is triggered by nematodes that cause the hydrangea leaves to become yellow and distorted. All these are highly unfavorable to the health of your plant.
6. Nutrient Deficiencies
If your hydrangea’s leaves turn yellow, it could signify that the plant lacks key nutrients. Nitrogen, phosphorus, and potassium are all essential for healthy plant growth, and deficiencies in any of these can cause leaves to turn yellow. A soil test can help determine if your hydrangea suffers from a nutrient deficiency.
7. Treatment With a High Level Of Fertilizer
Sometimes, too much of a good thing can be bad for your plants. If you’ve been treating your hydrangea with high fertilizer levels, this could cause yellowing leaves. Overfertilization can lead to nutrient burn, which causes leaves to turn yellow or brown. If you suspect overfertilization is the problem, stop fertilizing and see if the leaves return to their normal color.
8. Environmental Stressors
Yellowing leaves can also signify that your hydrangea is stressed due to environmental conditions. Too much sun or wind exposure can cause leaves to dry and turn yellow or brown. Extreme temperatures (either hot or cold) can also stress plants and cause leaf discoloration. If you think environmental stressors might be to blame, try moving your plant to a more sheltered location.
Treatment of Hydrangea Yellow Leaves
If you notice the leaves of your hydrangea turning yellow, there are a few things you can do to treat the problem.
Check If The Plant Is Getting Enough Water
Your hydrangeas plant needs to be watered regularly, particularly during hot weather. If the soil is dry, soak the plant very well. Ensure you’re watering your hydrangeas regularly and deeply, especially during hot weather.
Adjust to The Sunlight
You may also need to adjust the amount of sunlight the plant is getting. Move the plant to an area that gets partial shade.
Inspect The Plant for Signs of Disease
Yellowing leaves can be a sign of infection or pests. If you see any evidence of disease, treat it accordingly with pesticides or fungicides.
Check The Soil pH Level
Check the soil pH, and if you find out that this is the cause, amend it as necessary and accordingly. The ideal soil pH for hydrangeas is between 6.0 and 6.5.
Apply the Right Fertilizer
Apply a fertilizer formulated for acid-loving plants such as hydrangeas. Follow the package directions carefully, so you don’t over-fertilize the plant.
Check for Pests
Yellowing leaves can also be caused by pests such as aphids or scale insects feeding on the plant’s foliage. Inspect the leaves closely and if you see pests on your plants, treat them with an appropriate insecticide, such as insecticidal soap or neem oil if needed.
Call The Professionals
If you looked through and closely observed your hydrangea, but you’re still unsure of what it might be that is causing it to yellow around the leaves, pluck a leaf off your plant and take the yellowing leaf to your local nursery or a professional in flora and fauna. You will be told what the problem is and how to correct it.
Tending a Hydrangea Plant
If all the hydrangea you have been trying to grow seems to have been yellowing and stunted from inception and dies, likely, it has not been tended properly.
Caring for your plant begins right from the start. Taking stem cuttings from the mother plant in late summer or early fall, you should take cuttings from new growth at least 6 inches long.
Cut the plant stem at a forty-five-degree angle slightly under a leaf node. Remove the leaves from the bottom half of the cut and dip the cut end in rooting hormone powder. Put the cutting in a pot filled with moistened potting mix.
Cover the pot with a clear plastic bag, and make sure that the bag does not touch the leaves of the cutting. Position the pot in a warm, bright location away from direct sunlight. Keep the soil moist; within 4 to 8 weeks, roots will begin to form, and new growth will appear on the cutting.
Keep taking care of your plant by exposing it to sunlight, watering it appropriately, fertilizing it periodically, watching out for pests and diseases, and ensuring the soil is suitable for its growth. Preventive measures in tending your hydrangea are always better than corrective ones.