Malva × clementii [Ruby Star] ('Jostar')

RHS Plant Profile

tree mallow [Ruby Star]

Synonyms

Lavatera × clementii 'Jostar', Lavatera × clementii [Ruby Star], Malva × clementii 'Jostar'

Shrubs

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A semi-evergreen subshrub to around 1.8m high, with lobed and toothed grey-green leaves Clusters of rich cerise flowers with darker veins are produced at the tips of the stems from early to late summer

Position

Full sun

Soil Types

Chalk, Loam, Sand

Max Height

1.5-2.5 metres

Max Spread

1.5-2.5 metres

Size

Time to Maturity: 5–10 years
Max Spread: 1.5-2.5 metres
Max Height: 1.5-2.5 metres

Growing Conditions

Chalk Loam Sand

Moisture: Well–drained
pH: Acid or Alkaline or Neutral

Position

Full sun

Aspect: South–facing or West–facing
Exposure: Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H5

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Malvaceae
Native to GB/Ireland: No
Foliage: Semi evergreen
Habit: Bushy
Genus: Malva can be annuals, biennials or perennials, with rounded, often palmately lobed leaves and 5-petalled, open funnel-shaped flowers in the leaf axils or in terminal racemes
Name Status: Trade

How to Grow

Cultivation

Thrives in light, moderately fertile, well drained soil in full sun; may need support if grown in richer soils (see staking perennials). Shelter from cold winds in areas prone to frosts. May die back to a woody base in cold winters

Propagation

Propagate by softwood cuttings from stems or basal shoots in early summer. Plants can be short-lived so regular propagation is recommended. As this plant is protected by Plant Breeders' Rights, any propagation should be for personal rather than commercial use

Suggested planting locations and garden types

Cottage and informal garden
Gravel garden
Flower borders and beds
Wall side borders

Pruning

pruning group 6

Pests

May be susceptible to aphids

Diseases

May be susceptible to stem rot, a rust, and soil-borne fungal diseases