How to Grow Hardy Geraniums: Complete UK Care Guide

Hardy geraniums, commonly known as cranesbill, are among the most versatile and trouble-free perennials for UK gardens, forming attractive mounds or spreading mats of foliage topped with saucer-shaped flowers from late spring into autumn. Undemanding and adaptable to sun or shade, they make superb ground cover and respond brilliantly to a hard mid-season trim.

Attribute	Detail
Botanical name	Geranium spp. and cultivars (cranesbill)
Plant type	Herbaceous perennial
Height & spread	0.2–0.6m x 0.3–1m depending on variety
Hardiness	RHS H6-H7 (fully hardy)
Position	Full sun to partial or full shade, depending on species
Soil	Most well-drained soils; adaptable
Flowering period	May to October depending on variety
Difficulty	Easy

Choosing varieties

With so many species and cultivars available, hardy geraniums can suit almost any spot from sunny borders to dry shade under trees.

Variety	Flower colour	Habit	Notes
'Rozanne'	Violet-blue	Sprawling, spreading	Exceptionally long flowering, June–October
Geranium macrorrhizum 'Ingwersen's Variety'	Pale pink	Ground-covering mat	Thrives in dry shade, aromatic leaves
Geranium phaeum	Deep maroon-purple	Upright clumps	Good for deep shade, early flowering
Geranium 'Johnson's Blue'	Soft blue	Mounding	Classic cottage-garden favourite
Geranium sanguineum 'Max Frei'	Magenta-pink	Compact mound	Good for sunny, well-drained sites

Where and when to plant

Plant hardy geraniums in spring or autumn in well-prepared soil. Most are adaptable, tolerating sun or partial shade, though woodland species like Geranium phaeum and macrorrhizum cope with quite deep, dry shade under trees and shrubs. They work well as edging or filling gaps between shrubs; see our plants and grow guides for further planting combinations.

How to plant

1. Prepare the soil by removing weeds and lightly forking in compost.
2. Dig a hole slightly larger than the root ball.
3. Plant at the same depth as in its original pot.
4. Backfill, firm gently and water thoroughly.
5. Space plants 30–60cm apart depending on eventual spread.
6. Mulch lightly to suppress weeds while plants establish.

Watering and feeding

Water regularly until established, after which most hardy geraniums are fairly drought-tolerant, needing extra water only in prolonged dry spells. Feeding needs are modest; an annual spring mulch of garden compost is usually sufficient, though a light application of balanced fertiliser can boost flowering in poorer soils.

Pruning, cutting back and the mid-season chop

After the first flush of flowers fades, usually in midsummer, cut the whole plant back hard to around 5–10cm using shears. This mid-season chop removes tired foliage and spent flowers, and within a few weeks fresh leaves and a further flush of flowers appear, extending interest well into autumn. Cut remaining growth down in autumn or leave over winter for structure and cut back in early spring.

Dividing and propagation

Divide congested clumps every three to four years in spring or autumn, lifting the plant and pulling or cutting it into sections with roots attached. Replant divisions promptly and water well. Many geraniums, including Geranium phaeum, also self-seed freely, providing an easy, if less predictable, source of new plants.

Growing in pots

Compact varieties such as Geranium sanguineum cultivars grow well in containers using a peat-free multipurpose compost. Ensure good drainage and water more frequently than border plants, as pots dry out faster. Apply a mid-season chop as with border plants to keep container specimens flowering for longer.

Common problems

Problem	Symptom	Fix
Powdery mildew	White coating on leaves, especially late summer	Improve airflow, cut back affected growth, water at base
Sawfly larvae	Holes chewed in leaves	Pick off larvae by hand; generally cosmetic damage only
Legginess	Sprawling, floppy growth with few flowers	Apply the mid-season chop to rejuvenate
Slow establishment	Little growth after planting	Water consistently in first season and avoid deep planting

Month-by-month care calendar

Month	Task
March	Cut back any old winter foliage; mulch borders
April	Divide clumps if needed; plant new stock
May–June	First flush of flowers; water in dry spells
July	Perform mid-season chop after first flowering flush
August–September	Enjoy second flush of flowers, especially on 'Rozanne'
October	Divide clumps in mild weather if preferred to spring
Winter	Leave seed heads for structure or tidy back lightly