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Hydrangea problems

Most hydrangea distress is water-related rather than disease. Wilting in afternoon heat that recovers by morning is normal and needs no action.

Start from what you can see

Each of these has more than one possible cause, and each page separates them.

Hydrangea leaves turning yellowHydrangea wiltingHydrangea curling leavesHydrangea stunted growthHydrangea rotting fruitHydrangea stem rotHydrangea insects on the plantHydrangea brown leaf tipsHydrangea mottled leaves

Everything that commonly affects hydrangeas

Most serious first. Most of the list is treatable or can be ignored.

Herbicide DamageAct now

Growing conditions

Only new growth is affected; older leaves are untouched.

OverwateringAct now

Growing conditions

Wilting while the soil is wet. This combination is the whole diagnosis.

Root RotAct now

Fungal disease

Wilting that does not improve after watering, and often gets worse.

Spider MitesAct now

Pest

Fine even stippling rather than discrete spots or holes.

AphidsTreatable

Pest

Dense clusters on new shoots and flower buds rather than scattered individuals.

Grey Mould (Botrytis)Treatable

Fungal disease

Grey fuzzy growth that releases a visible puff of spores when touched.

Iron ChlorosisTreatable

Nutrient problem

Green veins on a yellow leaf — the net pattern is diagnostic.

Nitrogen DeficiencyTreatable

Nutrient problem

Whole leaf yellows evenly, veins included.

Slugs & SnailsTreatable

Pest

Silvery dried slime trails on leaves, pots or soil.

UnderwateringTreatable

Growing conditions

Leaves dry and crisp rather than soft and limp.

Powdery MildewMostly cosmetic

Fungal disease

White powder on the top of the leaf that rubs off with a finger.

SunscaldMostly cosmetic

Growing conditions

Damage on the side facing the sun, not the blossom end or stem end.

Check these two things first

  • Push a finger into the soil, two knuckles deep. Wet soil plus a wilting plant means too much water, not too little — and it is the commonest reason a plant is dying. Dry soil plus crisp leaves means the opposite. The leaves look nearly identical either way, so the soil is what tells you.
  • Turn a damaged leaf over. Half of all diagnoses live on the underside: fuzz means downy mildew, fine webbing means spider mites, clusters of insects mean aphids. Nothing on the top of a leaf is as informative.

Most garden problems are cosmetic and resolve without treatment. Reach for a spray last, not first.

Diagnose your hydrangea

Already filtered to hydrangeas. Add the symptoms and where the trouble started.

1.What plant is it?

Many problems are specific to one family, so this removes a large share of the list straight away.

2.What does it look like?

optional

Pick everything you can see. Any one match keeps a cause on the list, because you rarely see the whole picture at once.

3.Which part is affected?

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If the roots are involved you will have to unpot or dig to find out — and with a declining plant that is usually the most informative thing you can do.

4.Where did it start?

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The most underused question in plant diagnosis. Trouble that begins at the bottom means something very different from trouble that begins at the top.

12 likely causes
from 1 of 4 answered
4 of these can kill the plant — check those first
Ordered by how well the symptoms match, then by how much damage the cause can do. Rule out the top of the list first.