Streptocarpus 'Denim'

RHS Plant Profile

Cape primrose 'Denim'

RHS

Conservatory Greenhouse Houseplants

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An evergreen perennial to about 30cmproducing a rosette of hairy, strap-shaped leaves. Clusters of blue-purple flowers, 5cm across, white on the reverse and with white streaks on the upper lobes, are produced from early spring to late autumn

Position

Partial shade

Soil Types

Loam, Sand

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity: 2–5 years
Max Spread: 0.1-0.5 metres
Max Height: 0.1-0.5 metres

Growing Conditions

Loam Sand

Moisture: Moist but well–drained
pH: Acid or Alkaline or Neutral

Position

Partial shade

Aspect: South–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): H1C

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Gesneriaceae
Native to GB/Ireland: No
Foliage: Evergreen
Habit: Clump forming
Genus: Streptocarpus can be annuals, perennials or subshrubs, with usually wrinkled, lance-shaped to rounded leaves and clusters of tubular to trumpet-shaped flowers with 5 spreading lobes, often borne throughout the year
Name Status: Accepted

How to Grow

Cultivation

Grow as a houseplant in free-draining compost on an east or west-facing windowsill, or grow in a temperate or warm greenhouse in bright filtered light with shade from hot sun. Water sparingly as compost dries in winter and in the growing season water freely allowing compost to dry out between waterings; feed fortnightly with a high-potassium fertiliser. See Streptocarpus cultivation

Propagation

Propagate by leaf cuttings (see streptocarpus cultivation), or by division

Suggested planting locations and garden types

Patio and container plants

Pruning

No pruning required

Pests

May be susceptible to glasshouse leafhoppers, mealybugs, thrips, vine weevil and tarsonemid mite

Diseases

May be susceptible to grey moulds (botrytis) or powdery mildews