Hydrangea stunted growth
There are 4 common causes, and they need completely different responses — so working out which one you have matters more than treating quickly.
2 of them can kill the plant. Rule those out first.
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.
The 4 causes, and how to tell them apart
1.Herbicide Damage
Act nowGrowing conditions
New growth twisted, cupped, fern-like or strap-shaped, with stems that may spiral. Leaves take on a leathery texture and abnormally prominent parallel veins. Older leaves below stay entirely normal.
How to know it is this one
Only new growth is affected; older leaves are untouched.
2.Root Rot
Act nowFungal disease
Above ground, yellowing and wilting that looks like drought but does not respond to water. Below ground, roots that are brown or black, soft, and smell sour — healthy roots are firm and pale, and the outer sheath of a rotted root slides off leaving a thread.
How to know it is this one
Wilting that does not improve after watering, and often gets worse.
3.Aphids
TreatablePest
Clusters of small soft-bodied insects, usually green but also black, grey, pink or white, packed along new shoots and the undersides of young leaves. Leaves curl and pucker, and everything below becomes sticky with honeydew.
How to know it is this one
Dense clusters on new shoots and flower buds rather than scattered individuals.
4.Nitrogen Deficiency
TreatableNutrient problem
Uniform pale yellowing of the whole leaf, including the veins, starting with the oldest lowest leaves and working upward. Growth is slow and the plant looks generally thin and pale.
How to know it is this one
Whole leaf yellows evenly, veins included.
Still not sure?
The diagnostic key adds two more questions — which part is affected and where the trouble started — and those usually settle it.
Run the diagnostic key