Why won't my hydrangea bloom?

It may be due to late spring frosts damaging buds or pruning at the wrong time of year.

How do I make my flowers blue?

You can add aluminum sulfate to the soil to lower the pH and encourage blue pigment.

Plant guide

Bigleaf Hydrangea.

Hydrangea

Pronounced hy-DRAN-jee-uh mak-ro-FIL-uh

Also known as Hydrangea, Hydrangeas

Hydrangea macrophylla — Photo by zebedeugalinha (CC BY) via iNaturalist

Hydrangeas are beloved for their big, showy flower heads that can change color based on soil acidity. They bring a classic, lush feel to any garden space. These shrubs thrive when given plenty of room to spread out and show off their blooms.

Another photo of Bigleaf Hydrangea — Photo by Frank Ashwood (CC BY) via gbif

At a glance

Care level: Moderate
Plant type: Deciduous shrub
Light: Partial shade to morning sun
Indoor light: Bright indirect
Water: Every 2 to 4 days
Mature size: 3 to 6 feet
Growth rate: Medium
Hardiness: USDA 5 to 9
Bloom time: Late spring to late summer

Care

Keep the soil consistently moist but never soggy to prevent root issues. Watch for wilting leaves as a sign they need a drink, and keep an eye out for powdery mildew on the foliage. Pruning at the right time is key to ensuring you get flowers next season.

Watering: Water deeply whenever the top inch of soil feels dry to the touch.
Feeding: Apply a balanced fertilizer during the active growing season to support bloom production.
Pruning: Prune immediately after flowering to avoid cutting off next year's buds.
Repotting: Move to a larger container once the roots begin to circle the bottom of the pot.
Soil: Rich, well draining, organic soil
Soil pH: 5.0 to 7.0
Temperature: -20 to 35°C
Humidity: 50 to 70%
Drought tolerance: Low
Lifespan: Perennial, typically 10 to 20 years
Fragrance: Light
Deer and rabbits: Low

Signs it needs repotting

Roots growing out of the drainage holes
Water running straight through the pot
Stunted growth during the active season

Safety

People: All parts of the plant contain cyanogenic glycosides which can cause gastrointestinal distress if eaten.
Pets: This plant is toxic to cats and dogs if ingested.
Children: Keep this plant away from small children as ingestion of any part can lead to stomach upset.
Contact allergens: Handling the foliage can cause skin irritation in sensitive individuals due to fine hairs.
Airborne allergens: The pollen is generally not considered a significant airborne allergen.
Edibility: Hydrangea foliage and flowers are toxic if ingested and should never be consumed.

How to identify it

Large, serrated, oval shaped leaves
Massive clusters of showy flowers
Woody, upright shrub structure
Opposite leaf arrangement on stems

Height: 0.9 to 3m
Spread: 0.9 to 3m
Leaves: green, deciduous
Flowers: white, pink, blue, purple, red, 5 to 30cm

Problems to watch for

By symptom

Check your bigleaf hydrangea from a photo

Pocket Botanist looks at a photo of your plant and tells you what's wrong and what to try first.

Growing it

Propagation: cuttings, division, layering
When to plant: spring, autumn
Overwintering: Apply a layer of mulch around the base to protect roots from temperature swings. Avoid heavy pruning in autumn to protect next year's flower buds.
In containers: They grow well in large pots, provided you use a container at least 40 cm wide and ensure consistent watering.

Softwood Cuttings

1. Take a 10 cm cutting from a non flowering stem in early summer.
2. Remove the lower leaves and dip the cut end in rooting hormone.
3. Plant in a moist potting mix and cover with a plastic bag to maintain humidity.
4. Keep in bright, indirect light until roots form.

Plant hydrangeas with other moisture loving shade plants to create a lush, low maintenance garden bed.

Grows well with

Hostas — They thrive in the same shady, moist conditions as hydrangeas.
Ferns — Ferns provide a beautiful textural contrast to the large hydrangea leaves.

Similar species

Viburnum — These shrubs offer similar rounded flower clusters and deciduous habits.

Science

Family: Hydrangeaceae
Genus: Hydrangea
Order: Cornales
Class: Magnoliopsida
Native range: Asia and the Americas
Conservation: Not of conservation concern.

Hydrangeas typically grow in the understory of forests where they benefit from dappled light and moist, rich soil.

Value to wildlife: nectar source
Pollinators: bees, butterflies
Uses: ornamental shrub, cut flowers, dried arrangements

Through the year

JFMAMJJASOND

Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 5/9
Temperature: 5/9
Moisture: 7/9
Nutrients: 6/9
Light: 5/9

Taxonomy resolved against GBIF.

Questions people ask

Why won't my hydrangea bloom?: It may be due to late spring frosts damaging buds or pruning at the wrong time of year.
How do I make my flowers blue?: You can add aluminum sulfate to the soil to lower the pH and encourage blue pigment.

Where the name comes from

The genus name Hydrangea reflects the plant's need for consistent moisture, while the common name is a shortened version of this scientific title.

Good to know

The name comes from the Greek words hydro, meaning water, and angeion, meaning vessel, referring to the plant's high water needs.
Hydrangeas have been cultivated for centuries in Japan.
Some species can change color based on aluminum availability in the soil.

Also in

Keep your bigleaf hydrangea growing

This page is a general guide. Save your plant in Pocket Botanist and you get care reminders timed for this plant, plus a care history that shows what worked.

Get the app

This guide was generated with AI and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.