Endless Summer hydrangea

Sun

Morning sun and afternoon shade; light, open shade in hot climates. More sun is tolerated in cool areas if the soil stays moist.

Water

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

Soil

Humus-rich, moisture-retentive, well-drained soil. Acid soil with available aluminium encourages blue flowers; less acidic soil favours pink. Strongly alkaline soil can cause yellow leaves.

Height

3-5 ft (0.9-1.5 m)

Spread

3-5 ft (0.9-1.5 m)

Flowers

Summer into early autumn, with repeat flowering varying by climate and growing conditions; rounded heads of pink, blue or mauve flowers.

Foliage

Broad, toothed, dark green leaves; deciduous, with usually modest autumn colour.

Growth

Moderate

Care needed

Medium

• Heat tolerant
• Low allergen

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

Difficulty

Moderate

Toughness

Needs looking after

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

1. Planting day

   1.6 ft (0.5 m)

2. After 1 year

   2.1 ft (0.64 m)

3. After 2 years

   2.6 ft (0.78 m)

4. After 3 years

   3 ft (0.92 m)

5. After 5 years

   4 ft (1.2 m)

   full size

About 5 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

Moderate

• Water deeply at soil level when the upper soil begins to dry; check container plants frequently in warm weather.
• Apply 2-3 in (5-8 cm) of organic mulch in spring, keeping it clear of the stems.
• Feed modestly in spring with a balanced slow-release fertiliser; avoid heavy nitrogen feeding, which encourages leaves over flowers.
• Choose a position sheltered from drying winds and strong afternoon sun.
• Protect emerging shoots from late frost with horticultural fleece when frost is forecast.

Pruning. In spring, once buds begin to open, remove dead wood and cut old flowerheads back to the first strong pair of buds. Avoid routine hard pruning or autumn cutting, which removes buds for the earlier flowers; remove an occasional old stem at ground level only if the shrub is crowded.

Early spring

As buds open, remove dead stems and trim old flowerheads just above strong living buds.

Spring

Apply a modest feed and renew the organic mulch.

Late spring

Watch for late frost and cover tender new shoots overnight if needed.

Summer

Water deeply during dry spells, checking moisture beneath the mulch rather than watering by a fixed schedule.

Summer

If desired, remove faded flowers just above the first healthy pair of leaves without shortening the stems heavily.

Autumn

Leave healthy stems and remaining flowerheads intact; ensure containers drain freely before winter.

Winter

In colder areas, protect the root zone with mulch and shelter containers from severe freezing.

• Plant in a lightly shaded mixed border with ferns and hostas for contrasting leaf shapes.
• Repeat along a sheltered path or foundation for a loose, flowering rhythm rather than a tightly clipped hedge.
• Use in a large container near a shaded terrace, where watering is easy to manage.
• Group beneath high-canopied trees where there is good light and limited root competition for moisture.

Garden styles it suits: Cottage garden, English country, Woodland, Traditional, Hamptons and Pastel border.

Plant it with: Hostas, Japanese painted fern, Astilbes, Coral bells, Japanese forest grass and Camellias.

Wildlife: The showy mophead is dominated by sterile florets and offers relatively little nectar or pollen compared with lacecap hydrangeas. Dense growth provides some shelter for small garden animals.

• Few or no flowers: winter-damaged buds, late frost, heavy pruning, deep shade or excess nitrogen may be responsible. Preserve living stems, provide morning light and feed modestly; new-growth flowers may still develop later.
• Wilting and scorched leaves: check soil moisture and water deeply if dry; provide afternoon shade. Temporary midday drooping can occur even in moist soil, so do not automatically add more water.
• Leaf spots or powdery mildew: improve air circulation, water at soil level and remove fallen diseased leaves; most light infections are cosmetic.
• Yellow leaves with green veins: alkaline soil can make iron unavailable. Test the soil and use a suitable chelated iron treatment; on persistently chalky ground, consider growing in a container with suitable compost.

Toxic if eaten by cats, dogs, horses or people. Leaves, flower buds and other parts contain cyanogenic compounds. Most reported pet exposures cause vomiting, diarrhoea or depression; serious poisoning is uncommon but possible with substantial ingestion. Seek veterinary or medical advice after ingestion.

• Other mophead hydrangeas (Hydrangea macrophylla cultivars)

  Many are visually almost identical. A reliable label is needed to confirm 'Bailmer'; repeat flowering alone does not prove its identity.

• Smooth hydrangea (Hydrangea arborescens)

  Usually has thinner, less glossy leaves and white or pink flowerheads that do not turn blue with soil treatment; it flowers on new growth.

• Panicle hydrangea (Hydrangea paniculata)

  Has cone-shaped rather than rounded flowerheads, usually opening white or greenish and often ageing pink; the flowers do not turn blue.

Hydrangea comes from Greek words meaning water vessel, referring to the seed capsules, while macrophylla means large-leaved.

Propagation. Root softwood cuttings from healthy, non-flowering shoots in late spring or early summer, or layer a low stem. Seed does not reliably reproduce this cultivar; check local plant breeders' rights before propagating for sale.

Accepted botanical name

Hydrangea macrophylla

Native range

Japan and Kazan-retto.

Measured

Soil pH 4.5 to 8. Average height 150 cm.

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