Hydrangea macrophylla Magical Pink Ruby Yellow Leaves - Causes & Fixes

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Iron Chlorosis (Nutrient Deficiency)

In Hydrangeas, yellowing between the veins (interveinal chlorosis) is often caused by an inability to absorb iron due to high soil pH. This prevents the plant from producing sufficient chlorophyll.

Very Common

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How to confirm: Inspect if the leaf veins remain green while the rest of the leaf tissue turns pale yellow.

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shopping_cart Recommended Products

1 Apply an iron-rich supplement or acidifying fertilizer to lower the soil pH and make iron more available to the roots.

FoxFarm Happy Frog Acid Loving Plant Fertilizer

Organic

$22

In Stock

2 Monitor soil acidity levels regularly to ensure the pH remains in the acidic range (5.2 to 5.5) for optimal iron uptake.

YAMRON 4-in-1 Digital Soil Tester

Water Meters

$33

In Stock

3 Amend the existing soil with organic matter like compost or peat moss to help maintain a lower pH and improve nutrient availability.

Espoma Organic Potting Soil Mix

15.1 L

$22

In Stock

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Overwatering and Root Suffocation

Hydrangeas prefer moist but well-drained soil; constant saturation deprives roots of oxygen, leading to yellowing foliage. This condition can eventually cause root rot in the 'Magical' series cultivars.

Very Common

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How to confirm: Stick your finger two inches into the soil to see if it feels waterlogged or muddy.

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1 Immediately stop watering and allow the soil to dry out significantly before the next application to restore oxygen to the root zone.

GROWIT Soil Moisture Meter SMM-V3

Water Meters

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2 Repot the hydrangea into a container with superior drainage, incorporating perlite to improve aeration and prevent future waterlogging.

3 Ensure the plant is in a pot with adequate drainage holes and use a saucer to catch excess water, but empty the saucer after use to prevent the plant from sitting in stagnant water.

Bleuhome 10" Plant Saucer 6-Pack Black

Pot Saucers

$20

In Stock

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Nitrogen Deficiency

A lack of nitrogen results in a uniform yellowing of older leaves, starting from the bottom of the plant. This occurs when the soil lacks sufficient organic matter to support large-leafed species.

Common

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How to confirm: Check if the yellowing is progressing uniformly across the entire leaf surface starting from the base of the plant.

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shopping_cart Recommended Products

1 Apply a nitrogen-rich organic fertilizer to the soil to replenish essential nutrients and restore green foliage.

FoxFarm Grow Big Liquid Plant Food 1 Quart

0.9 L • 1 pcs

$30

In Stock

2 Incorporate organic matter like worm castings or compost into the soil to improve long-term nutrient availability and soil structure.

Back to the Roots Organic Worm Castings 5lb

Worm Castings

$17

In Stock

3 Monitor soil moisture levels using a moisture meter to ensure the plant is not experiencing water stress, which can exacerbate nutrient uptake issues.

GROWIT Soil Moisture Meter - Blue

Water Meters

$12

In Stock

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Hydrangea Leaf Spot (Fungal Pathogen)

Pathogens like Cercospora can cause leaves to turn yellow and eventually drop, especially in humid conditions with poor airflow. This is often accompanied by small dark spots on the yellowing tissue.

Common

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How to confirm: Look for small, dark necrotic spots appearing on the yellowed areas of the leaves.

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1 Remove and discard all heavily infected or yellowing leaves to prevent the fungal pathogen from spreading to healthy foliage.

2 Apply an organic fungicide to treat the infection and protect remaining healthy leaves from further spread.