Clethra alnifolia

RHS Plant Profile
summer sweet

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summer sweet RHS

Other common names

bush pepper, common white alder, nana, pink spire, sweet pepper bush

Shrubs
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An erect, bushy, suckering shrub not usually exceeding 2m. The fresh green leaves are simple, obovate, neatly serrrate, sometimes turning yellow in autumn. Near-white scented flowers are abundantly produced, in erect terminal racemes, in summer. Pink selections are available

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
Correct
Plant Range
E N America

How to Grow

Cultivation

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

Propagation

Propagate by seed in spring or autumn; propagate by softwood cuttings in early summer

Suggested planting locations and garden types

  • Cottage and informal garden
  • Low Maintenance

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