Purple cranesbill

Purple cranesbill: how do you recognise it?

Habit

Dense, rounded clump about 60 cm tall and as wide, spreading slowly.

Leaves

Round, palmately and deeply cut, softly hairy; orange to red in autumn.

Flowers

Saucer-shaped, 4–5 cm across, violet-blue with dark veins; in June, sometimes into early July.

Fruit

Sets no seed, as the plant is sterile.

Roots

Short, fleshy rhizomes; the clump gets a little wider every year.

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

Why grow it?

• A sea of violet-blue flowers in June, busy with bees and bumblebees.
• Indestructible and long-lived: a clump can stay in the same spot for many years.
• Grows in sun and partial shade, on sand, loam and clay, acid or chalky.
• Lovely autumn colour: the hairy leaves turn orange to red.
• Sterile, so no seedlings popping up all over the border.

Purple cranesbill: where does it grow best?

• Full sun or partial shade; it flowers most freely in sun.
• Any ordinary garden soil: sand, loam or clay, acid to chalky.
• Moist but not waterlogged soil, especially in winter.
• Allow 40–50 cm between plants; in groups of three or five they soon knit together.

Light

Sun and partial shade

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Normal

Size

0.6 m tall, 0.6 m wide

Hardiness

Hardy (to -35 °C)

Goes well with

• Roses: A classic: the blue suits pink, white and apricot, and the clump hides the bare base of the shrub.
• Lady’s mantle: Lime-green froth beside the violet-blue, in the same sun or partial shade.
• Ornamental onion: Purple globes rising above the leaves at about the same time.
• Peony: Also flowers in June and likes the same sunny spot.
• Catmint: Carries the blue on into September, after the cranesbill has finished.

Purple cranesbill: when and how to plant it?

Plant in March–April and September–October.

1. Plant in March–April or September–October, when the soil is not frozen or too wet.
2. Dig a hole twice as wide as the pot and mix in a spadeful of compost.
3. Set the plant at the same depth as in the pot, with the buds just below the surface.
4. Space plants 40–50 cm apart, or plant them in groups of three.
5. Firm the soil well and water in thoroughly straight away.
6. Keep the soil moist for the first few weeks, until the plant has rooted in.

Care

Watering

Weekly for young plants in dry spells. After that only during prolonged drought.

Feeding

A little compost around the clump in March is enough. Too much fertiliser gives soft growth that flops.

Mulching

A thin layer of compost or leaf mould in spring keeps the soil moist and suppresses weeds.

Support

Rarely needed. On rich soil or after a downpour it falls open; a low ring of twigs helps.

After flowering

The clump falls apart after flowering: cut everything back then (see pruning).

Tip: Cut everything back straight after flowering, in July, and give it a can of water: within a few weeks you will have a fresh mound of leaves and sometimes a small second flush.

Purple cranesbill: when to prune it?

Pruning months: March and July.

When: Straight after flowering, usually in July. In March, remove the old, withered leaves.

How:

• After flowering, cut all stems and leaves back to 5–10 cm above the ground.
• Then water and give a little compost: within a few weeks a fresh mound of leaves appears.
• A small second flush sometimes follows in August.
• In March, clear last year’s dead leaves before the new shoots appear.

Caution: If you do not cut it back, the clump stays untidy and splayed open for the rest of the summer.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April or September–October. Cut the clump with a spade into pieces, each with a few buds and roots, and replant them straight away.

Seed

Not possible: this hybrid is sterile and sets no seed. Always propagate it by division.

Purple cranesbill: how does it get through the winter?

Hardy to −35 °C.

• Very hardy, to about −35 °C: no protection is needed in Belgium.
• The leaves die back in winter; the plant regrows in March–April.
• In a pot: stand it in a sheltered spot against a wall and make sure it never sits in water.

Diseases and pests

• Slugs: They eat the young leaves in spring. Pick them off in the evening and keep the soil around the clump free of debris.
• Powdery mildew: White powder on the leaves, mainly in dry summers. Cut off affected leaves and water; the new leaves are usually healthy.
• Flopping clump: Normal after flowering. Cutting back solves it; feed less if it happens before flowering every year.
• Few flowers: Too much shade or an old, bare clump. Move it to a sunnier spot or divide it.

Through the year

• March: Remove old leaves. Spread compost around the clump.
• April: Plant or divide. Watch for slugs on the young leaves.
• May: The clump grows quickly. Add a low support if needed.
• June: Full bloom. Plenty of bees and bumblebees.
• July: After flowering, cut everything back hard. Water and give compost.
• August: Fresh leaves, sometimes a small second flush. Water in dry spells.
• September: Plant or divide.
• October: Orange and red autumn colour. Planting is still possible.
• November: The leaves die back. Rest.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• Because it is sterile, it does not form the beak-shaped fruits that give cranesbills their name.
• The ‘geraniums’ on windowsills are really pelargoniums; the true Geranium is a hardy perennial like this one.
• Its parents, Geranium ibericum and Geranium platypetalum, grow wild in the mountains of the Caucasus.