Wallich’s cranesbill

Wallich’s cranesbill: how do you recognise it?

Habit

Low plant 30 cm tall with trailing stems that spread up to 1 m from a single central rootstock.

Foliage

Deeply cut into 3–5 toothed lobes, slightly hairy; conspicuous, leaf-like stipules along the stems.

Flower

Saucer-shaped, about 3 cm, from July to October; blue to violet with a white centre.

Fruit

A dry, beaked fruit that flings out its seeds when ripe.

Roots

A single fleshy, deep rootstock; this is why it is hard to divide.

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

Why grow it?

• Flowers from July into October, long after most cranesbills have finished.
• The trailing stems weave through other plants and fill the gaps left after the summer flush.
• A popular late source of nectar for bees and bumblebees.
• Covers the ground without spreading invasively: it grows from one point and does not root along its stems.
• Lovely at the foot of roses and shrubs, in a large container or spilling over a low wall.

Wallich’s cranesbill: where does it grow best?

• Sun to partial shade; in full sun it needs soil that does not dry out, in partial shade it still flowers well.
• Humus-rich soil that holds moisture without staying wet: sand, loam or clay, acid to chalky.
• Normally moist soil; prolonged summer drought holds back flowering.
• Allow about 1 m per plant, or let the stems weave between lower neighbours.

Light

Sun and partial shade

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Normal

Size

0.3 m tall, 1 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Shrub roses: The blue stems creep around the bare base of the roses.
• Japanese anemone: Flowers at the same time, pink or white next to the blue.
• Lady’s mantle: Soft green leaves and tiny lime-green flowers at the front of the border.
• Ornamental grasses: Low grasses give the flowering stems an airy backdrop.
• Michaelmas daisy: Even more late flowers for bees and bumblebees.

Wallich’s cranesbill: when and how to plant it?

Plant in March–May and September.

1. Plant in March–May or in September, when the soil is neither frozen nor parched.
2. Dig a generous hole and mix in a few spadefuls of compost or leaf mould.
3. Set the plant at the same depth as it was in the pot: the buds at the top of the rootstock must not be buried.
4. Allow about 1 m of space, or place it between taller plants that the stems can grow through.
5. Water in well straight away and keep the soil moist during the first season.
6. Spread a layer of leaf mould around the base.

Care

Watering

In the first year during dry spells; later only in long dry periods, especially in a sunny spot.

Feeding

A layer of compost around the plant in April is enough.

Mulching

Leaf mould in spring keeps the roots cool and moist.

Guiding the stems

In summer, gently guide the stems between neighbouring plants or over a low shrub so that they do not smother smaller plants.

Deadheading

Not needed: it keeps flowering on its own until the first frost.

Tip: Plant it next to plants that leave a gap after June, such as oriental poppy: by August the flowering stems will have filled the empty space.

Wallich’s cranesbill: when to prune it?

Pruning months: March.

When: In March, before the new leaves emerge. Do not prune it in summer, or you lose the late flowers.

How:

• In March, cut the old, dead stems and old leaves back to the rootstock.
• Take care not to damage the young buds in the centre of the plant.
• Stems that smother smaller neighbours can be shortened in summer; it costs a few flowers but does the plant no harm.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Basal cuttings

In April: cut young shoots from the base with a small piece of rootstock and insert them in gritty cutting compost under plastic. They root within a few weeks.

Seed

Sow ripe seed in autumn in a pot and leave it outdoors. ‘Buxton’s Variety’ comes fairly true from seed, with some variation in colour.

Division

Difficult, because it grows from a single rootstock. Only try it in spring, with a piece that has its own roots and buds.

Wallich’s cranesbill: how does it get through the winter?

Hardy to −25 °C.

• Hardy to about −25 °C: the top growth dies back, but the rootstock survives Belgian winters without trouble.
• Leave the dead stems in place until March; they protect the centre of the plant.
• In a pot: stand the pot in a sheltered spot against a wall and make sure the compost does not stay soaking wet.

Diseases and pests

• Slugs: Young shoots are eaten in April–May. Pick slugs off in the evening and keep the base clear of debris.
• Powdery mildew: White powder on the leaves in dry late summers. Water in dry spells and cut off affected leaves.
• Few flowers: In deep shade or on dry, poor soil. Give it more light and a layer of compost.
• Rootstock rot: In heavy, wet soil the rootstock can rot in winter. Improve the soil with compost and do not plant in a hollow.

Through the year

• March: Cut away old leaves and dead stems. Apply compost.
• April: Plant. Take basal cuttings. Watch out for slugs.
• May: Plant. The stems lengthen: guide them between neighbours.
• June: Water in dry spells.
• July: Flowering begins.
• August: In full flower. Bees and bumblebees on the flowers.
• September: In flower. Plant. Collect seed.
• October: Last flowers. Sow seed in a pot outdoors.
• November: Leave the dead stems until spring.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The species is named after Nathaniel Wallich, a Danish surgeon and botanist who ran the botanic garden in Calcutta in the 19th century.
• Unlike many ground-cover plants, its stems do not root: the whole plant grows from a single point.
• It is one of the latest-flowering cranesbills: in mild weather it still has flowers in October.