Tardiva hydrangea

Sun

Full sun to partial shade; afternoon shade is helpful in hot climates. Too much shade reduces flowering.

Water

Keep the root zone evenly moist, especially during establishment and hot, dry weather; avoid waterlogged soil.

Soil

Moist, well-drained soil enriched with organic matter; tolerates clay if drainage is adequate. Soil pH does not turn the flowers blue.

Height

8-12 ft (2.4-3.7 m)

Spread

7-10 ft (2.1-3 m)

Flowers

Late summer into autumn; loose, pointed panicles of small fertile flowers and larger white sterile florets, aging pink and then tan.

Foliage

Deciduous, pointed, oval green leaves with toothed edges; autumn colour is usually modest, sometimes yellow.

Growth

Moderate to fast once established.

Care needed

Low

• Pollinators
• Cold hardy
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1.6 ft (0.5 m)

2. After 1 year

   4 ft (1.1 m)

3. After 2 years

   6 ft (1.8 m)

4. After 3 years

   8 ft (2.4 m)

5. After 5 years

   10 ft (3.1 m)

   full size

About 4 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Growth rate

Fast

• Water deeply during dry spells, checking that moisture reaches below the surface.
• Spread 2-3 in (5-8 cm) of organic mulch over the root zone, keeping it clear of the stems.
• Apply a balanced shrub fertiliser in spring only if growth is weak or the soil is poor; avoid heavy nitrogen feeding.
• Allow room for its mature width rather than repeatedly clipping it into a small space.
• In hot regions, choose a site with afternoon shade and reliable moisture.

Pruning. Prune in late winter or early spring before growth starts: remove dead, damaged and crossing wood, then shorten last year's shoots as needed to maintain a strong framework. It flowers on new growth; repeated hard cutting produces larger flower heads but can encourage weak, floppy stems.

Late winter

Prune before new growth begins, retaining a sturdy framework.

Spring

Plant when the soil is workable, water thoroughly and mulch the root zone.

Late spring

Check new shoots for aphids and dislodge small colonies with water.

Summer

Water deeply during dry spells, especially while flower buds develop.

Late summer

Enjoy the late-opening flowers; cut a few stems for indoor arrangements if wanted.

Autumn

Plant in mild climates while the soil is still warm; leave dry flower heads for winter structure if desired.

• Place at the back of a broad mixed border with asters and ornamental grasses for late-season flowers.
• Grow as an informal flowering screen where its full mature width can develop.
• Use as a specimen beside a lawn or terrace, allowing space for arching branches.
• Plant along a sunny woodland edge with shade-tolerant perennials toward the sheltered side.

Garden styles it suits: English country, Cottage garden, Traditional, Woodland, Autumn colour and White garden.

Plant it with: Japanese anemones, Asters, Switchgrass, Black-eyed Susans, Hostas and Hardy geraniums.

Wildlife: The small fertile flowers offer food to visiting bees and other insects. Deer may browse leaves and young shoots.

• Wilting or scorched leaf edges: check soil moisture, water deeply and mulch; provide afternoon shade in hot locations.
• Few flowers: improve light and avoid pruning after spring growth is underway; very short summers can also limit this late cultivar.
• Aphids on soft shoots: wash them off with a firm spray of water and encourage natural predators.
• Leaf spots or powdery mildew: improve airflow, water at soil level and remove badly affected fallen leaves.

Toxic to cats, dogs, horses and people if eaten. Leaves, buds and other parts contain cyanogenic compounds; ingestion usually causes digestive upset, but larger amounts can be serious. Seek medical or veterinary advice after ingestion.

• Peegee hydrangea (Hydrangea paniculata 'Grandiflora')

  Usually has denser, heavier flower heads dominated by large sterile florets and generally flowers earlier; 'Tardiva' has a looser, more open panicle.

• Smooth hydrangea (Hydrangea arborescens)

  Has rounded or broadly domed flower heads rather than long, pointed panicles and usually forms a smaller, suckering shrub.

• Bigleaf hydrangea (Hydrangea macrophylla)

  Has broader, thicker leaves and rounded mophead or flat lacecap flowers; some cultivars turn blue in suitable acidic soil, unlike 'Tardiva'.

Hydrangea comes from Greek words for water and vessel, referring to the seed capsules, paniculata describes the branched flower clusters, and 'Tardiva' refers to its late flowering.

Propagation. Take softwood cuttings in late spring or early summer, or root a low branch by layering. Seedlings will not reliably retain the characteristics of 'Tardiva'.

Accepted botanical name

Hydrangea paniculata

In the US and Canada

Introduced in Canada and the lower 48 states.

Native range

China North-Central, China South-Central, China Southeast, Japan, Kuril Is., Sakhalin and Taiwan.

Measured

Average height 580 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.