Clethra alnifolia 'Sixteen Candles'

RHS Plant Profile

white alder 'Sixteen Candles'

Janet Cubey

Shrubs

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'Sixteen Candles' is a compact, upright, deciduous shrub with glossy foliage turning yellow in autumn. Bears groups of upright, tapering, candle-like spikes of sweet-scented, white flowers in summer

Position

Full shade, Partial shade

Soil Types

Clay, 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

Clay Loam Sand

Moisture: Moist but well–drained
pH: Acid

Position

Full shade Partial shade

Aspect: South–facing or North–facing or West–facing or East–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

Fragrance Flower

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Clethraceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Bushy
Genus: Clethra can be deciduous or evergreen trees or shrubs, sometimes with attractive bark, with simple leaves and small, fragrant, usually white, bell-shaped flowers in racemes or panicles
Name Status: Accepted

How to Grow

Cultivation

Grow in fertile, humus-rich, moist but well-drained acid soil, best in part or dappled shade

Propagation

Propagate by softwood cuttings in early summer

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Low Maintenance
Flower borders and beds

Pruning

Pruning group 1; remove some of the old wood from the base in winter, leaving the strongest suckers as replacement growth

Pests

Generally pest-free

Diseases

Generally disease-free