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Herbaceous Perennial

Phlox paniculata 'Blue Boy'

perennial phlox 'Blue Boy'

A strong-growing herbaceous perennial 90-120cm high with green lance-shaped leaves and large clusters of scented, mauve-blue flowers, with darker purple and white eyes, from summer to early autumn

Synonyms

Phlox paniculata 'Boy Blue'

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Ultimate height

0.5–1 metres

Time to ultimate height

2–5 years

Ultimate spread

0.5–1 metres

Clay

Loam

Moisture

Moist but well–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun

Aspect

West–facing or South–facing or East–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)

Botanical details

Family: Polemoniaceae
Native to the UK: No
Foliage: Deciduous
Habit: Clump forming
Genus: Phlox may be evergreen or herbaceous, mat-forming or erect perennials or shrubs, with simple leaves and salver-shaped flowers in terminal clusters
Name status: Accepted

How to grow

Cultivation

Grow in fertile, humus-rich, moisture-retentive soil in full sun, and every autumn add a thick mulch of organic material to help preserve soil moisture

Propagation

Propagate by division in autumn or spring, by basal cuttings in spring or by root cuttings from early autumn to spring; root cuttings are the best method to ensure healthy plants

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Prairie planting
Wildlife gardens
Cut flowers
Flower borders and beds
Wall side borders

Pruning

Deadhead to prolong flowering; cut down to the base in late autumn and remove the cut stems, to reduce the risk of eelworm and mildew the following year

Pests

Generally pest-free but may be susceptible to slugs, snails, aphids, and Phlox stem eelworm

Diseases

Generally disease-free but may be susceptible to crown gall, leafy gall, fungal leaf spot and Verticillium wilt; said to have good resistance to powdery mildews

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