Bigleaf hydrangea
Sources last read 14 September 2026.
Middling It gives warning, with time to act.
Also called French Hydrangea, Hortensia, Lacecap Hydrangea, Mop-head Hydrangea, mophead hydrangea, penny mac and Snowball Plant.
Bigleaf hydrangea is toxic
- Not assessed for cats. This plant is not on the ASPCA list. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
- Not assessed for dogs. This plant is not on the ASPCA list. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
- Toxic to people. Can cause skin allergy. Use gloves and protective gear when handling it. RHS
What the sources say about its care
- Light
- Full sun, Partial shadeRHS · read 13 September 2026
- Water
- Moist but well-drainedRHS · read 13 September 2026
- Humidity
No source read publishes a humidity figure for any plant on this site. What follows is general guidance for foliage plants.
ASHRAE recommends indoor relative humidity between 30% and 60% 30–60%Penn State Extension · read 13 September 2026- Temperature
How cold this tolerates, not what it prefers. No source read for this site publishes a preferred range for a plant indoors.
H5 — -15 to -10°C -15 to -10 °CRHS · read 13 September 2026- Soil
- Clay, Loam, Sand; pH Acid or Alkaline or NeutralRHS · read 13 September 2026
- Toxic to cats
- Not on the ASPCA list. That is not a finding of safety.ASPCA · read 13 September 2026
- Toxic to dogs
- Not on the ASPCA list. That is not a finding of safety.ASPCA · read 13 September 2026
- Harmful to people
- Can cause skin allergy. Use gloves and protective gear when handling it.RHS · read 13 September 2026
How it usually goes wrong
- A thin dry rim that crumbles between the fingers
Leaves on the side of the bigleaf hydrangea nearest a heater or vent brown at the edges while those on the far side stay clean.
Heated air holds less water than the plant loses into it, so moisture leaves the leaf faster than it arrives. Penn State Extension cites ASHRAE's indoor range of 30% to 60% relative humidity, and winter heating often takes a room below it. That applies while it is grown indoors; its RHS rating of H5 describes a plant that also grows outside, where the air is seldom that dry.
Telling it apart: What else in the room changed. Edges that browned when the radiators came on point at the air rather than at the watering.
Penn State ExtensionBigleaf hydrangea leggy, leaning growth: causes- Buds form and fall before they open
Buds on the bigleaf hydrangea stop swelling, turn pale at the base and fall, usually a few at a time over a week or two.
Its source places it in full sun, partial shade. A bud formed in that light and then turned away from it, or left in drying compost, is the first thing the plant gives up.
Telling it apart: What happened in the fortnight before the buds dropped. A move, a turned pot or a dry spell is the usual answer.
RHSDiagnose leaf drop on this Bigleaf hydrangea- Dry, bruised edges after a cold, windy spell
Marks on the bigleaf hydrangea are concentrated on the windward side: torn edges, dry brown patches and leaves rubbed against each other.
RHS lists it for a sheltered position. Wind pulls water from the leaf faster than roots replace it, and it bruises the tissue it strikes, so a plant grown out in the open is marked on its windward side.
Telling it apart: Which side. Wind marks the side facing it; dry soil marks the whole plant.
RHSDiagnose brown tips and edges on this Bigleaf hydrangea- Pale dry areas across the upper leaves only
Upper surfaces lose colour while the undersides stay green, and nothing below the top of the plant is touched.
Its source names full sun, partial shade, yet a leaf grown in lower light has thinner tissue than one grown in sun, and it scorches if moved into strong light in one step.
Telling it apart: Whether it followed a move or a season. Scorch appears within days of a change in position.
RHSBigleaf hydrangea leaves turning yellow: causes- Yellow, limp leaves at the base
On a bigleaf hydrangea the yellowing climbs from below. Affected leaves feel limp rather than papery, and water sits in the saucer long after it drains through.
Soil described as moist but well-drained is a drainage instruction as much as a watering one. Compost that stays saturated suffocates the fine roots that do the drinking.
Telling it apart: The soil, not the leaf. Wet compost under yellowing leaves points one way and dry compost the other, and the leaves alone will not tell you which.
RHSBigleaf hydrangea leaves turning yellow: causes
Not sure which it is? Ask the diagnosis questions for Bigleaf hydrangea.
Routine care
- Propagation
- This shrub can be propagated by layering or stem cuttings.NC State Extension · read 13 September 2026Root softwood cuttings during early summer or hardwood cuttings during winter.RHS · read 13 September 2026
- Pruning
- Finish any pruning before August 1.NC State Extension · read 13 September 2026Follow pruning group 4, which has more advice and a video guide.RHS · read 13 September 2026
- Pests and diseases
- Can be troubled by vine weevil, hydrangea scale, capsid bug and aphids. Diseases: honey fungus, powdery mildews, grey moulds and a leaf spot can occur.RHS · read 13 September 2026
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Photographs
About the plant
Hydrangea macrophylla is a species of flowering plant in the family Hydrangeaceae, native and endemic to Japan. It is a deciduous shrub growing to 3 m (10 ft) tall by 2.5 m (8 ft) or more broad with large heads of pink or blue flowers in summer and autumn. It is currently treated as monotypic, with no subspecies or varieties. Common names include bigleaf hydrangea, and, for particular cultivar groups, the names lacecap hydrangea, mophead hydrangea, and hortensia. It is widely cultivated in many parts of the world in many climates. It is not to be confused with H. aspera 'Macrophylla'.
From Wikipedia, CC BY-SA 4.0 · read 13 September 2026
- Native range
- SC. Japan (to Izu Ōshima), Kazan RettōWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP · read 13 September 2026Japan, China, Korea and Southeast Asia;NC State Extension · read 13 September 2026JapanRHS · read 13 September 2026
- Climate
- temperateWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP · read 13 September 2026
- Growth form
- Perennial, Shrub; habit erect, multi-stemmed, roundedNC State Extension · read 13 September 2026Bushy (deciduous)RHS · read 13 September 2026
- Size
- Height 36–72 in; width 36–72 inNC State Extension · read 13 September 2026Height 1.5-2.5 metres; spread 1.5-2.5 metres after 5–10 yearsRHS · read 13 September 2026
- Flowering
- Flowers blue, pink, purple/lavender, white; blooms in summerNC State Extension · read 13 September 2026Flowers blue in summer; pink in summerRHS · read 13 September 2026
Common problems with Bigleaf hydrangea
Plants with similar care
African violetBrown tips on the newest leaves first
Bird of paradiseCrisp margins that appear in winter
Busy LizzieBrown brittle margins with a green centre
Calla lilyEdges of the leaves brown while the middle stays sound
CamelliaBrown brittle margins with a green centre
Cape leadwortCrisp margins that appear in winter
Sources
- ASPCA · read 13 September 2026
- Kew WCVP · read 13 September 2026
- NC State Extension · read 13 September 2026
- Penn State Extension · read 13 September 2026
- RHS · read 13 September 2026
- Wikipedia · read 13 September 2026
What this does not cover
The figures above are what published sources say, not measurements of the plant in your room. They say nothing about your pot size, your water, the season, or how far from the glass the plant stands, and those decide more than any figure here does.
Humidity has no species figure because no source read for this site publishes one, and the only temperature published for this plant is a cold floor. The simulator fills those gaps with general figures for its kind of plant, marked as general and listed on how we read sources. Where a toxicity row says the plant was not assessed, that is the absence of a finding and not a finding of safety.
If something is already wrong, the diagnosis tool asks about the soil, the window and the watering, which is where the answer usually is.