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Problems With Hydrangeas in Pots: Why Yours Keeps Wilting

A potted hydrangea drinks more than any other shrub and wilts daily in summer. Pot size, compost and afternoon shade fix most of it.

By Zakaria 3 min read Save to Pinterest — opens Pinterest in a new tab
Hydrangea pot flowers
Photo: JillWellington, Pixabay Content License, via Pixabay
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A potted hydrangea drinks more than any other common shrub and has a fraction of the roots to do it with. Nearly every problem traces back to that.

Why it wilts every afternoon

Large thin leaves lose water fast. In the ground the roots range widely to keep up; in a pot they have maybe a tenth of that volume.

So on a hot day the plant simply outruns its reservoir, and wilts. It is not necessarily diseased, underfed or dying.

Fixing the wilt, in order of effect
ChangeEffect
Bigger potLargest single improvement
Afternoon shadeVery large. Halves the demand
Moisture-retentive compostSignificant — loam-based holds better than peat-free multipurpose alone
Mulch on the compost surfaceSignificant, and free
Larger saucer, brieflyShort-term relief in heat; do not leave it standing
Watering more oftenNecessary, but it treats the symptom

Repeated severe wilting does lasting damage

A plant that collapses daily and recovers each evening still ends up with scorched leaf margins and fewer flowers the following year.

Treat chronic wilting as a setup problem, not a watering schedule problem.

The flowering question

Mophead and lacecap hydrangeas (H. macrophylla) flower on last year’s wood. Cut them back in autumn or spring and you have removed this year’s flowers.

  • Deadhead only, down to the first fat pair of buds, in spring
  • Leave old flowerheads on over winter — they shelter the buds beneath
  • Remove a few of the oldest stems at the base for renewal, not the whole plant
  • Paniculata and arborescens types are different — those flower on new wood and can be cut back hard in late winter

Other reasons a potted one does not flower: too much shade, a pot too small to support blooming, too much nitrogen, and frost damage to buds — which is a real risk in a container, where roots and stems are far more exposed than in open ground.

Compost and feeding

  • Loam-based compost (John Innes No. 3 or equivalent) holds water and nutrients better than multipurpose alone
  • Mix in some multipurpose for structure if it feels heavy
  • Mulch the surface with bark or gravel
  • Feed in spring with a balanced or high-potash feed. Avoid high nitrogen, which makes leaves at the expense of flowers
  • Repot every two or three years, going up a size

Winter

The roots are the vulnerable part — in a pot they sit in air on all sides rather than insulated by soil.

  1. Move the pot to a sheltered spot against a wall
  2. Raise it on feet so it drains freely
  3. Wrap the container in bubble wrap, hessian or straw
  4. Do not wrap the plant in plastic — it needs air
  5. Keep compost just moist. Frozen saturated compost damages roots
  6. Leave last year’s stems on mophead types

Common questions

Why does my potted hydrangea keep wilting?

Because the pot cannot hold enough water for the plant's leaf area. Hydrangeas have large thin leaves that transpire heavily, and in a container the root volume is a fraction of what the same shrub would have in the ground, so on a hot day it empties the pot by afternoon. Daily watering in summer is normal and twice daily is not unusual in heat. The fix is a bigger pot, compost that holds moisture, mulch on the surface, and moving it out of direct afternoon sun.

What size pot does a hydrangea need?

At least 40 to 50 cm across and the same deep for a standard mophead or lacecap, and larger is genuinely better. Most potted hydrangeas are sold in containers far too small for long-term growth, and a plant kept in one will wilt constantly, flower poorly and eventually decline. Repot into something substantial in its first spring, and expect to go up again every two or three years.

Why is my potted hydrangea not flowering?

Most often it was pruned at the wrong time. Mophead and lacecap hydrangeas flower on growth made the previous year, so cutting them back in autumn or spring removes that season's flower buds entirely. The other common causes are too much shade, a pot too small to support flowering, excess nitrogen feed producing leaves instead of blooms, and frost damage to the buds in an exposed container, since roots and buds in a pot are far more exposed than in the ground.

Should I move a potted hydrangea out of the sun?

Usually yes, at least from the midday and afternoon sun. Hydrangeas in containers do best with morning sun and afternoon shade, because the pot heats up and the plant cannot replace water fast enough under strong light. A plant in full all-day sun will wilt daily however much you water it, and repeated severe wilting scorches the leaf margins and reduces flowering.

How do I overwinter a hydrangea in a pot?

Protect the roots, which are far more exposed than they would be in the ground. Move the pot against a sheltered wall, raise it on feet so it drains, and wrap the container — not the plant — in bubble wrap, hessian or straw. Keep the compost just moist rather than wet, since frozen saturated compost damages roots badly. Do not cut off last year's stems on mophead types, because they carry the flower buds, and the old growth also gives the buds some shelter.

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