<em>Stewartia pseudocamellia</em>, false camellia: planting, pruning, care

Description and botany

Stewartia or Stuartie is a small tree or large bush of the family Theaceae, like tea and its better-known cousin camellia to which it is closely related. The genus comprises about 80 species of trees and shrubs native to wooded mountains or stream banks of Japan, South Korea, China and North America. American species such as Stewartia ovata are considered vulnerable or endangered and are rare in our latitudes.

Four main species are cultivated for ornamental purposes in gardens:

• Stewartia pseudocamellia, sometimes nicknamed Stewartia false-camellia, and its varieties such as Stewartia pseudocamellia ‘Koreana’ with large flowers
• Stewartia rostrata, very hardy (down to -20°C)
• Stewartia monadelpha, favoured by bonsai enthusiasts for its regularly tiered silhouette
• Stewartia sinensis with very attractive decorative bark

All flower in summer and are valued for their autumn colours as well as for their colourful bark in winter.

Slow to establish and slow-growing, it eventually forms after many years a true small tree that will rarely exceed 5–6 m in our gardens, with a spread of 3–5 m at ripeness, whereas in its native regions it can reach up to 15 m. It displays a fine, well-balanced set of branches from the base. Its slowness is matched only by great longevity; venerable specimens of two to three hundred years old are known.

Stewartia sinensis – botanical illustration

Habit differs markedly according to species: conical and ramified very low, even columnar in Stewartia pseudocamellia, in a spreading pyramidal crown then becoming trailing with time in S. rostrata, erect and regular in Stewartia monadelpha. Crown generally rounds with age.

Stewartia is noted for its extremely decorative bark that peels with age. Its smooth cinnamon-red bark exfoliates in fine plates from pink to grey-beige, orange to violet-brown according to variety, very attractive in winter. Only Stewartia rostrata has an unremarkable bark.

In Stewartia, the deciduous and elegant foliage remains attractive outside flowering since it takes on splendid autumn colours. These glossy, entire, obovate to elliptical leaves, rather leathery, are 3–10 cm long, with strongly marked veins and finely dentate margins. Silky and paler beneath, they are bright to dark green until late summer, more rarely variegated with cream in some cultivars, then take on tones from orange to scarlet and purple before falling late in autumn.

From May–June to August, Stewartia produces numerous flower buds that open into simple, delicate flowers. They appear solitary in the axil of leaves and bloom along the shoots. They open as widely flared silky cups 3–6 cm across, made of 5 rounded pure white petals, sometimes streaked with pale pink, edged by elongated or slightly twisted sepals in Stewartia rostrata. They display a yellow or purplish centre with yellow-orange or violet anthers, depending on variety. Their infinite delicacy recalls the shape of wild rose or camellia flowers, hence the nickname false camellia; “Pseudocamellia” in Latin also means “resembling camellia”. Sometimes the petal edge is attractively fringed. The short life of individual flowers is compensated by abundance as they succeed one another for nearly two months. Although scentless, they lend great elegance.

Plant in light shade, sheltered from cold winds, in preferably acidic soil such as heather soil, not too calcareous, that remains cool even in summer.

Slow-growing, Stewartia suits all garden sizes and can be used in a flowering hedge, planted as a solitary specimen, on the forest edge or in the heart of a shaded border.

Latin name refers to John Stuart, botanist and 18th-century British prime minister.

Main species and varieties

Most popular

Stewartia pseudocamellia

This species is most widely cultivated. Everything about it is lovely: flower, fruit, autumn foliage, even bark! Relatively compact, suits gardens of all sizes.

• Flowering time August, September
• Height at maturity 4,50 m

See the product sheet

Stewartia pseudocamellia Koreana

This cultivar differs from the type species by having broader leaves and more open flowers. It is one of the hardiest (down to -25°C). Plant as solitary specimen, or with other plants that prefer non-calcareous soil.

• Flowering time July to September
• Height at maturity 6 m

See the product sheet

Our favourites

Stewartia rostrata

One of the hardiest and least demanding regarding soil; its summer flowering is more abundant and more colourful than that of other Stewartia. Its bark is, however, fairly ordinary. Ideal for a small garden.

• Flowering time July
• Height at maturity 6 m

See the product sheet

Stewartia monadelpha

A species well known to bonsai enthusiasts who appreciate it for its regularly tiered silhouette, its extremely decorative bark and its splendid autumn colours.

• Flowering time July to September
• Height at maturity 6 m

See the product sheet

Planting

When to plant Stewartia?

Hardy in ground (from -15°C to -25°C depending on species), Stewartia is fairly easy to acclimatise except perhaps in Mediterranean climate, too hot and dry in summer. In regions with long winters, however, place in very sheltered spot as late frosts can damage buds and young shoots, especially on young specimens, which are more fragile.

Native to woodland understorey, it favours cool conditions and is best grown in partial shade, tolerating full sun only if soil remains cool. It dislikes dense shade. Regarding soil, it is less demanding than its cousin camellia: it will do on ordinary, neutral or slightly acidic soil, preferably fresh, light and humus-bearing, not too dry and without excess lime.

With slow growth and compact habit, it suits modest-sized gardens. Still, allow enough room so it can develop freely; allow roughly 2 to 5 metres spread. It does not tolerate transplantation well; consider siting carefully before planting.

It will be magnificent either as a specimen in the middle of a short grass meadow, or in a small flowering hedge, or in a bush border, alongside other plants for non-calcareous soil (Magnolias, Rhododendron, azaleas, Hydrangea, Hamamelis, Pieris, Camellias, Kalmias, Japanese Maples), or in a large pot on the terrace.

When to plant Stewartia?

Planting in spring, from March to April after the severest frosts, will favour re-establishment.

How to plant Stewartia?

In ground

If soil is too calcareous, improve it by adding heather soil. Allow a planting space 5 to 6 m wide. Once established, avoid moving it, roots do not tolerate being transplanted.

• Dig a hole three times wider than rootball and 40 to 50 cm deep; Stewartia must not be planted too deeply
• Plant bush in a mix of compost and heather soil: top of rootball should be covered by 3 cm
• Keep bush upright
• Spread an organic mulch of pine bark or dead leaves
• Water regularly for first 15 days after planting to keep soil cool

In pot

Small ultimate size of Stewartia makes it entirely suitable for container use. It tolerates pot culture very well in regions south of the Loire; elsewhere potted specimens will be more vulnerable to severe frosts. It will be happy in a wide container (30 to 40 cm diameter) filled with a fresh, very free-draining mix, based on 1/3 heather soil, 1/3 potting compost and 1/3 garden soil not too calcareous, kept constantly moist as in a pot it will not tolerate drought, even brief.

Place a layer of gravel or clay pebbles at bottom of container before planting.

Stewartia pseudocamellia : flower and autumn foliage

Maintenance, pruning and care

In summer, monitor water needs during first year after planting for young Stewartia: water once a week and thoroughly in dry weather; soil must never be dry, as it dislikes drought and likes its roots kept cool during summer heat. Once well rooted, water only during very hot spells.

Apply an organic mulch (pine needles, which will acidify soil) to keep roots cool in summer.

In winter, water occasionally if no rain.

In autumn, you can fertilise with a little compost, lightly forking it in around base.

In regions north of the Loire, protect the bush from severe frost by covering the stump with a 5–7 cm-thick mulch made of leaf mould and shredded bark. If late frosts are a concern, cover with horticultural fleece. Young plants must be protected from severe frost for at least 3 years.

Pruning is not necessary for Asian species; they do very well without intervention. However, pruning can be useful to clear lower part of trunk to showcase bark in winter.

About every 3 years, after flowering, from February to April:

1. Remove crossing branches and dead wood
2. Trim back branch tips slightly to rebalance branches

Grown in good conditions, Stewartia is little vulnerable to diseases and parasitic organisms. However, too calcareous soil can cause chlorosis, responsible for yellowing of leaves and, in time, decline of tree.

Multiplication

Stewartia is rather difficult to propagate; sowing is possible but tedious and very slow (between 2 and 5 years for germination), layering is still possible for branches closest to the ground, but results are slow too and separation of a viable layer usually takes 2 years. We recommend stem cuttings in spring.

How to propagate?

Allow 1 year for complete rooting.

• In May–June, take shoots 10 cm long
• Remove all leaves from lower part of cutting
• With a small knife, strip bark over 2 to 3 cm
• Insert cuttings into a well-draining mixture of turf and perlite
• Place in shade, enclosed under plastic to retain humidity
• Mist cuttings regularly with a spray bottle
• During summer, pot cuttings into buckets
• Overwinter them in frost-free conditions until following spring
• Plant in open ground the following spring

Pairing Stewartia with other plants in the garden

Still too little known, Stewartia is nevertheless a very handsome bush that fits easily into any garden provided it can be given a shady spot. Magnificent all summer with its profusion of large white flowers, it is also essential for enlivening the garden in autumn with foliage that turns sumptuous colours and in winter with its coloured bark. As it dislikes lime, it pairs easily with ericaceous plants. It is the perfect guest for white gardens or romantic gardens to which it brings great softness and freshness.

An example of a combination: Stewartia with beneath its canopy blue Hostas (‘Fragrant Blue’, ‘Halcyon’, or variegated blue (‘June’, ‘Frances Williams’, ‘El Niño, ) Milium effusum ‘Aureum’, Brunnera macrophylla ‘Jack Frost’ or another variety, Campanula poscharskyana ‘Stella’ or the species

Its large white flowers provide good brightness and its glossy green foliage brings density to a large, rather dull semi-shaded border. Position it at the back of the border mixed with shade-loving acidophilous plants like small rhododendrons, finely cut-leaved ferns and Hostas, which will offer an ideal contrast of form.

Against a permanent green background of conifers and bushes with evergreen foliage, it will be stunning alongside Calycanthus, Hamamelis and Fothergilla, equally charming bushes.

In summer, Stewartia also makes a fine grouped specimen at the edge of woodland. It will combine well with shrubs such as Andromeda, Azaleas, Kalmia, Camellias and Hydrangeas that will accompany its flowering.

In a flowering hedge, it will sit well with a fine Cornus kousa, viburnums, Mexican orange blossom, spiraeas or Deutzia.

To set alight the shaded corners of the garden in autumn, think of Acer, Chinese azaleas, Leucothoe, Nandina, tulip tree with their splendid autumn hues to accompany it.

For a colourful winter garden and to showcase its decorative bark, why not plant it near the very original Edgewortha chrysantha, and dogwoods with colourful wood such as Cornus alba ‘Bâton Rouge®’.

You can also dress the base of this Asian tree with a few Japanese primroses, a Magellan fuchsia or autumn bulbs such as white Naples cyclamens.