Ocimum basilicum 'Dark Opal'

RHS Plant Profile

basil 'Dark Opal'

Synonyms

Ocimum basilicum var. purpurascens 'Dark Opal'

Annual Biennial Herbs - Culinary

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A striking, upright, bushy annual producing stunning, dark purple, almost black, aromatic foliage that has a strong liquorice flavour. Attractive spikes of small, tubular, cerise red flowers appear in summer. Highly ornamental for warmer gardens in the UK, otherwise grow indoors under glass

Position

Full sun

Soil Types

Loam, Sand

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity: 1–2 years
Max Spread: 0.1-0.5 metres
Max Height: 0.1-0.5 metres

Growing Conditions

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): H1C

Colour & Scent

Fragrance Foliage

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Lamiaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Bushy
Genus: Ocimum can be aromatic annuals, evergreen perennials or shrubs with opposite, linear to broadly-ovate leaves and small tubular white or pinkish flowers in whorls forming a spike
Name Status: Accepted

How to Grow

Cultivation

Grow as an annual, indoors, in moist but well drained soil in a sheltered position in full sun. Can move outdoors in summer. Best grown in a container. See basil cultivation for more information

Propagation

Propagate by seed in gentle heat in spring under glass or indoors, or sow in-situ in summer. See sowing seeds indoors for further advice

Suggested planting locations and garden types

City and courtyard gardens
Mediterranean climate plants
Patio and container plants
Conservatory and greenhouse

Pruning

Pinch out flower heads as they appear to encourage continued leaf growth. If left to flower, cut back after flowering

Pests

May be susceptible to aphids, slugs, snails and leafhoppers

Diseases

May be susceptible to powdery mildews