Empress Wu hosta

Sun

Partial shade to full shade; gentle morning sun is suitable, but avoid hot afternoon sun.

Water

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

Soil

Deep, fertile, humus-rich soil with good drainage; tolerates mildly acidic to mildly alkaline conditions.

Height

3-4 ft (0.9-1.2 m), with flower stalks rising above the foliage

Spread

5-8 ft (1.5-2.4 m)

Flowers

Pale lavender flowers on tall stalks in early to midsummer.

Foliage

Huge, heart-shaped leaves with pronounced veins and a puckered surface; blue-green when young, becoming dark green through the season.

Growth

Moderate; often takes 4-5 years or longer to develop its full size.

Care needed

Medium

• Pollinators
• Cold hardy
• Heat tolerant
• Low allergen

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

Difficulty

Moderate

Toughness

Fairly tough

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

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   1.8 ft (0.55 m)

3. After 2 years

   2.6 ft (0.8 m)

4. After 3 years

   3 ft (1.1 m)

   full size

About 3 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 during dry spells, particularly beneath trees where roots compete for moisture.
• Apply compost around the clump in spring; use a balanced slow-release fertiliser only if growth or soil fertility is poor.
• Mulch with 2-3 in (5-8 cm) of organic material, keeping it clear of the crown.
• Allow room for the mature spread rather than planting small neighbours close to the crown.
• Leave established clumps undisturbed unless division is needed; routine division is unnecessary.

Pruning. Cut spent flower stalks down to the base after flowering if you do not want seedheads. Remove collapsed leaves after autumn frost or before new shoots emerge in spring, using clean tools.

Early spring

Clear old foliage before new shoots emerge and check for slugs around the crown.

Spring

Plant or transplant while conditions are cool, then water thoroughly and apply mulch.

Late spring

Check soil moisture as the large leaves expand, especially near trees.

Summer

Water deeply in dry weather and watch for scorched leaf margins.

After summer flowering

Remove spent flower stalks if a tidier appearance is wanted.

Late autumn

Remove collapsed foliage and maintain drainage around the dormant crown.

• Use a single mature clump as a focal point in a broad shaded border.
• Pair with ferns and fine-leaved sedges to contrast with its massive leaves.
• Plant beside a shaded path or terrace, allowing enough setback for the mature foliage.
• Use beneath high-canopied deciduous trees where soil can be kept moist.
• Place near a pond for bold foliage, but above the saturated water margin.

Garden styles it suits: Woodland, Architectural minimal, Japanese, Green on green, English country and Pacific Northwest woodland.

Plant it with: Japanese painted fern, Astilbe, Brunnera, Japanese forest grass, Epimedium and Solomon's seal.

Wildlife: Flowers provide nectar for bees and may attract hummingbirds in North America. Deer, rabbits, slugs and snails may eat the foliage.

• Slugs and snails chew holes in emerging and mature leaves. Hand-pick at dusk, remove nearby hiding places and use labelled iron-phosphate bait where needed.
• Deer can strip the foliage. Use a suitable deer fence or protect plants with locally effective repellents.
• Hosta virus X can cause unusual mottling, ink-like markings along veins and distorted leaves. Remove infected plants; do not divide them, and disinfect cutting tools between plants.
• Sun scorch and drought cause brown edges or bleached patches. Provide afternoon shade, water deeply and mulch; existing damage will not heal.

All parts contain saponins and are toxic to cats, dogs and horses if eaten, commonly causing vomiting, diarrhoea or abdominal discomfort; substantial ingestion warrants veterinary advice. Hostas are not generally regarded as poisonous to people, and young shoots of some hostas are eaten, but this ornamental cultivar should not be treated as a food plant.

• Blue Angel hosta (Hosta 'Blue Angel')

  Another giant hosta, but its leaves usually retain a stronger blue-grey cast; Empress Wu becomes greener as the season progresses.

• Sum and Substance hosta (Hosta 'Sum and Substance')

  Its large leaves are chartreuse to golden yellow rather than the dark green of mature Empress Wu foliage.

• Elegans hosta (Hosta sieboldiana 'Elegans')

  It has strongly puckered blue-grey leaves but usually forms a substantially shorter, smaller clump.

The cultivar name honours Wu Zetian, the woman who ruled China as emperor during the seventh century.

Propagation. Division preserves the cultivar; seed does not reliably come true. Where propagation rights permit, divide in early spring as shoots emerge, retaining several buds and a good root system on each piece; check local plant breeders' rights before propagating this named cultivar.

Accepted botanical name

Hosta

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