Arends' phlox

Phlox × arendsii

In other languages: Flox (Nederlands) · Phlox d’Arends (Français)

This phlox is a cross between woodland phlox (Phlox divaricata) and garden phlox (Phlox paniculata), raised in the early twentieth century by the German nurseryman Georg Arends. It combines the best of both: the generous flowering and scent of garden phlox on a lower, more compact plant 40–60 cm tall. From June to September it carries loose clusters of flat, star-shaped flowers in lilac, pink or white, often with a darker eye. It starts flowering earlier than most garden phlox. Well-known cultivars are ‘Hilda’ (white with a lilac eye) and ‘Luc’s Lilac’ (lilac).

Updated on 9 October 2026

Light
Sun or partial shade
preferably some sun
Moisture
Normal
no wet feet
Legal basis
Loam or clay
acid to neutral
Hardiness
Fully hardy
down to -30 °C
Size
0.6 m
tall, 0.45 m wide
Flowering
June–September

Key facts
Pruning months	March and July–August
Height	0.6 m
Native to Belgium	No, planted
Good for bees, butterflies and birds	Yes, for bees and butterflies
Poisonous to people and pets	Not known to be poisonous
Flowering	June–September

Identify

Arends' phlox: how do you recognise it?

Habit: Upright, dense clump 40–60 cm tall and about 40 cm wide.
Leaves: Narrowly oval to lance-shaped, opposite, dark green.
Flower: Flat, star-shaped flowers of 2–2.5 cm in loose clusters at the tips of the stems.
Colour: Lilac, lavender, pink or white, often with a darker eye.
Scent: Soft and sweet, especially on warm days.

Flowering: June–September · Plants: March–May and September–October · Pruning: March and July–August

In your garden

Why grow it?

Long flowering, from June to September, if you remove faded clusters.
Softly scented flowers that you notice as you walk past.
Attracts bees and especially butterflies.
More compact than garden phlox: it flops less and suits the front or middle of the border.
Happy in both sun and partial shade.

Arends' phlox: where does it grow best?

Sun to partial shade; in full midday sun it dries out faster.
Fertile, humus-rich soil: loam or clay, acid to neutral.
Evenly moist: it dislikes drying out in summer.
Plant 40 cm apart and leave air between plants, to prevent mildew.

Light: Sun and partial shade
Soil type: Loam or clay
Acidity: Acid or neutral
Moisture: Normal
Size: 0.6 m tall, 0.45 m wide
Hardiness: Hardy (to -30 °C)

Goes well with

Hardy geranium: A low, long-flowering neighbour for the front of the border.
Lady’s mantle: Soft green leaves and yellow sprays as a fresh edging.
Sage: Violet-blue spikes next to the rounded clusters; a feast for bees.
Roses: A classic cottage-garden pairing in pink and white.
Ornamental grasses: Light plumes that keep the border airy.

Maintenance

Arends' phlox: when and how to plant it?

Plant in March–May and September–October.

Plant from March to May or in September–October.
Dig a generous hole and mix in a few spadefuls of compost.
Set the plant at the same depth as it was in the pot and firm the soil well.
Space plants 40 cm apart, in groups of three or five for the best effect.
Water in well and mulch with leaf mould.

Care

Watering: In dry summers, water deeply once a week, at the base and not over the leaves.
Feeding: Compost or an organic fertiliser in spring.
Mulching: A layer of compost or leaf mould keeps the soil cool and moist.
Deadheading: Cut faded clusters back to just above a leaf; the side shoots will flower again.
Rejuvenating: Divide every 3–4 years to keep the clump young and free-flowering.

Tip: Cut faded clusters straight away, just above a few leaves: the side shoots form new buds and it keeps flowering into September.

Arends' phlox: when to prune it?

Pruning months: March and July–August.

When: Remove faded clusters in July–August; clear last year’s dead stems in March.

How:

Cut faded clusters back to just above the next leaf or small side shoot.
In March, cut all old stems back to a few centimetres above the ground.
In spring, thin a dense clump by removing a few weak shoots at the base: more air and less mildew.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division: In March–April or September–October, split the clump into pieces with a few shoots and roots.
Root cuttings: In winter, lay 5 cm pieces of root in cutting compost; this gives plants free of stem eelworm.
Softwood cuttings: In April–May, root cuttings of young shoots in moist cutting compost.

Arends' phlox: how does it get through the winter?

Hardy to −30 °C.

Fully hardy, down to about −30 °C: no protection needed.
The top growth dies back and the plant shoots again in spring.
In a pot: stand the pot against a wall so the root ball does not freeze solid.

Diseases and pests

Powdery mildew: White powder on the leaves in summer, especially in dry weather. Water at the base, thin the clump and remove affected leaves.
Stem eelworm: Tiny worms inside the stems: narrow, crinkled leaves and swollen, split stems. Discard affected plants and propagate from root cuttings.
Slugs: They eat the young shoots in spring. Pick them off in the evening.
Drought stress: Limp, yellow lower leaves in dry weather. Mulch and water deeply.

Through the year

January: Take root cuttings.
March: Cut back old stems. Plant or divide. Add compost.
April: Plant. Take softwood cuttings. Watch out for slugs.
May: Plant. Mulch. Thin the clump.
June: Flowering begins.
July: Full flower. Remove faded clusters. Water in dry weather.
August: Remove faded clusters for a second flush.
September: Second flush. Plant or divide.
October: Plant or divide.

Use

Good for wildlife

Bees: Nectar and pollen for honeybees and wild bees.
Butterflies: Nectar for butterflies.

You and this species

Did you know?

Phlox is Greek for ‘flame’, a reference to the bright colours of some species.
Georg Arends also gave his name to the well-known Astilbe × arendsii, which he bred at the same nursery in Germany.
Both parents come from North America, but the cross was made in Europe.

Garden plants · All species