Japanese stewartia

Japanese stewartia: how do you recognise it?

Habit

Small tree or large shrub, 6–8 m tall and 4–5 m wide, with a straight trunk and a pyramidal to rounded crown.

Leaves

Ovate to elliptic, 5–10 cm, finely toothed, dark green; autumn colour yellow, orange and red.

Flowers

White, cup-shaped flowers 5–6 cm across with wavy petals and a ring of orange-yellow stamens, in July–August.

Bark

Peeling; on older trees a mosaic of grey, orange and reddish-brown.

Roots

Fine, shallow and fibrous. It transplants badly and dislikes drought.

Flowering: July–August · Plants: March–April and October–December · Pruning: February

Why grow it?

• Interest in four seasons: flowers, autumn colour, bark and a fine winter structure.
• Large white flowers in July–August, when few trees bloom; they attract bees.
• Lovely autumn colour in yellow, orange and red.
• Peeling bark in a mosaic of grey, orange and reddish-brown on older trees.
• Stays compact (6–8 m) and suits a smaller garden.

Japanese stewartia: where does it grow best?

• Partial shade, or sun with some shade in the heat of the day; morning sun gives the richest flowering.
• Acid, humus-rich, loose sandy or loamy soil. Avoid lime: the leaves turn yellow.
• Evenly moist and well drained: drought costs flower buds, wet feet cause root rot.
• Shelter from cold wind and late frost. Allow 4–5 m of space.

Light

Sun and partial shade

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Normal

Size

8 m tall, 5 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Rhododendron: Likes the same acid, humus-rich soil and light shade.
• Japanese maple: Fine foliage and autumn colour in a similar style.
• Pieris: Evergreen acid-loving shrub that flowers in spring.
• Hosta: Large leaves in the light shade at the base.
• Ferns: A fresh, green underplanting for moist shade.

Japanese stewartia: when and how to plant it?

Plant in March–April and October–December.

1. Plant from October to December or in March–April, when the soil is neither frozen nor waterlogged.
2. Choose a young potted tree: it roots better than a bare-root tree.
3. Dig a hole twice as wide as the root ball and just as deep. Mix the excavated soil with leaf mould.
4. Plant at the same depth as in the pot: the root collar stays at soil level, no deeper.
5. Water in at once with 10–15 litres, preferably rainwater.
6. Spread a 5–8 cm layer of leaf mould or bark around the base, keeping it clear of the trunk.

Care

Water

Keep the soil evenly moist: weekly in dry spells in the first year and in summer, when the buds form. Rainwater is better than tap water, as it contains less lime.

Feeding

In spring, a fertiliser for acid-loving plants or organic feed.

Mulching

Every year a layer of leaf mould or bark: the roots stay cool and moist.

Flowers

Each flower lasts only a short time, but new ones open for weeks. There is no need to clear up the fallen flowers.

Moving

Preferably not: it roots poorly again after transplanting. Choose the right spot straight away.

Tip: Give it a sheltered spot with acid, humus-rich soil and partial shade. If the roots stay cool and moist, it flowers richly. Plant it where you can see the bark in winter.

Japanese stewartia: when to prune it?

Pruning months: February.

When: Hardly necessary. If needed, do it in February, during dormancy, in frost-free weather.

How:

• Remove dead, damaged and crossing branches.
• Keep the natural shape: it needs no formative pruning.
• If you want to show off the bark, remove a few of the lowest branches over several years.

Caution: Prune sparingly: it recovers slowly from heavy cutting and loses its natural shape.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings

Semi-ripe cuttings about 10 cm long in July–August, in sandy cutting compost under plastic and with rooting powder. They root slowly and not always.

Seed

Seed germinates slowly and unevenly, sometimes only after a year or more. Sow it in autumn in a tray that you leave outdoors over winter.

Japanese stewartia: how does it get through the winter?

Hardy to −25 °C.

• Hardy to about −25 °C: usually without protection in Belgian winters.
• On young trees, a layer of mulch protects the roots during hard frosts; shelter them from cold east winds.
• It can also be grown in a pot: use a roomy pot with acid compost, wrap the pot in hessian and put it in a sheltered spot.
• The peeling bark makes the bare tree attractive in winter.

Diseases and pests

• Yellow leaves (chlorosis): Pale yellow leaves with green veins on chalky soil. Mulch with leaf mould and water with rainwater. On chalky soil, choose a pot with acid compost.
• Brown leaf edges: Caused by drought, wind or fierce afternoon sun. Provide a sheltered spot, mulch and even watering.
• Bud drop or few flowers: Drought while the buds form, too much shade or a still young tree. Water enough in summer; a young tree only flowers after a few years.
• Root rot: A yellowing, wilting tree on soil that is too wet. Plant in free-draining soil and improve drainage.

Through the year

• February: If needed, remove dead branches.
• March: Plant. Feed sparingly with a fertiliser for acid-loving plants.
• April: Plant. Mulch.
• May: Watch for late frost on young shoots. Water in dry weather.
• June: Water in dry weather: the buds are forming.
• July: Flowering begins. Take semi-ripe cuttings. Water.
• August: Flowering. Water in dry weather.
• September: Water in dry weather.
• October: Plant. Autumn colour yellow, orange and red.
• November: Plant. Top up the mulch.
• December: Plant. Admire the bark.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• It is related to the camellia (both belong to the Theaceae family), hence the name pseudocamellia, ‘false camellia’.
• The genus Stewartia is named after John Stuart, Earl of Bute, a British patron of botany.
• Each flower lasts only a short time, but the tree keeps flowering for weeks.