Physostegia virginiana 'Alba'

RHS Plant Profile

obedient plant 'Alba'

Herbaceous Perennial

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A clump-forming perennial with upright stems to 90cm tall clothed with sharply-toothed leaves and spikes of densely-packed, white, tubular flowers followed by green seed pods

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.5-1 metres

Size

Time to Maturity: 2–5 years
Max Spread: 0.5-1 metres
Max Height: 0.5-1 metres

Growing Conditions

Chalk Clay Loam Sand

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

Position

Full sun Partial shade

Aspect: South–facing or East–facing or West–facing
Exposure: Exposed or 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): H7

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Lamiaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Clump forming
Genus: Physostegia are erect rhizomatous herbaceous perennials with neatly arranged pairs of toothed leaves and terminal racemes of 2-lipped, tubular flowers in summer
Name Status: Accepted

How to Grow

Cultivation

Grow in moist but well-drained, moderately fertile soil in full sun or partial shade

Propagation

Propagate by division in early spring

Suggested planting locations and garden types

Cottage and informal garden
Flower borders and beds
Cut flowers

Pruning

Cut back to the base in winter

Pests

Generally pest-free

Diseases

May be suceptible to rots if the rhizomes are damaged