Geranium macrorrhizum (big-root cranesbill) — Mound-forming or spreading

Overview

Geranium macrorrhizum is a mound-forming or spreading perennial in the genus Geranium, part of the Geraniaceae family, with deciduous or semi-evergreen; rounded, palmately lobed, often aromatic foliage. It typically grows around 0.5 m tall. Geranium macrorrhizum grows best in full sun to partial shade, and tolerates most soils and acid and neutral or alkaline pH. Its UK hardiness is rated H5–H7. Suggested uses include groundcover, borders, rock gardens and woodland gardens. It is native to S Europe and Turkey.

About

Geranium macrorrhizum is a mound-forming or spreading perennial with rounded, palmately lobed leaves that are often aromatic when crushed. It reaches about 0.5 m and may be deciduous or semi-evergreen depending on exposure. Flowers appear in the UK from June to September. It suits full sun to partial shade and tolerates a wide range of soils provided they are well drained and not parched.

Wikipedia contributors, CC BY-SA 4.0 — Geranium macrorrhizum

About the genus

Geranium is a genus of 422 species of annual, biennial, and perennial plants that are commonly known as geraniums, hardy geraniums, or cranesbills. They are found throughout the temperate regions of the world and the mountains of the tropics, with the greatest diversity in the eastern part of the Mediterranean region.

Wikipedia contributors, "Geranium", CC BY-SA 4.0 — Geranium

In the garden

Geranium macrorrhizum belongs to the Geraniaceae and originates from south-eastern Europe and Turkey. Its habit ranges from compact mounds to a more spreading ground cover, and the leaves are distinctly palmately lobed and fragrant when bruised. In the UK it reliably produces summer blooms from June to September and typically reaches around 0.5 m in height. Plant it in full sun to partial shade on almost any reasonable soil type — loam, chalk, sand or clay will all do as long as drainage is adequate and the soil is not bone dry. It tolerates a wide soil pH (acid, neutral or alkaline) and can be placed in exposed or sheltered positions; hardiness H5–H7 means it is hardy through most UK conditions (USDA 4–9 for wider reference). An aspect of any orientation is acceptable, so long as moisture and drainage suit the site. Use Geranium macrorrhizum as a ground cover between shrubs, at the front of borders, in rock gardens or under trees in woodland-style plantings. Its mound-forming habit helps suppress weeds and knit planting edges together. Note that the leaves are aromatic when crushed, a practical detail to consider when siting plants near paths or seating.

Growing conditions

Best soil and position for Geranium

Sunlight: Full sun to partial shade
Soil type: Almost any reasonable soil — loam, chalk, sand or clay
Soil pH: Acid, neutral or alkaline
Soil moisture: Well drained but not parched
Aspect: Any
Exposure: Exposed or sheltered
UK hardiness: H5–H7

Plant details

Geranium macrorrhizum size, habit and characteristics

Plant type: Perennial
Habit: Mound-forming or spreading
Foliage: Deciduous or semi-evergreen; rounded, palmately lobed, often aromatic
Height: 0.5 m
Suggested uses: Groundcover, Borders, Rock gardens, Woodland gardens
Native to: S Europe, Turkey
Fragrance: Foliage

Care notes

Pruning and caring for Geranium macrorrhizum

Cultivation: Among the least demanding of perennials, asking only for reasonable drainage and an open position. Shear the whole plant back hard after the first flush and water it in; most kinds then produce fresh foliage and a second showing by late summer.
Pruning: Cut back to a low framework after the first flowering to renew the foliage and prompt repeat bloom. Tidy any remaining growth in late autumn or early spring.
Propagation: Divide in spring or autumn. Many species self-seed freely, and basal cuttings suit cultivars that resent disturbance.
Pest resistance: Largely untroubled, though vine weevil grubs attack the roots of container plants and sawfly larvae occasionally strip leaves.
Disease resistance: Powdery mildew and rust may appear on congested plants in a dry summer; shearing back usually resolves both.

Frequently asked questions

How do I grow Geranium macrorrhizum?

Among the least demanding of perennials, asking only for reasonable drainage and an open position. Shear the whole plant back hard after the first flush and water it in; most kinds then produce fresh foliage and a second showing by late summer.

Where is the best place to plant Geranium macrorrhizum?

Geranium macrorrhizum prefers full sun to partial shade. It suits exposed or sheltered positions.

What soil does Geranium macrorrhizum need?

Geranium macrorrhizum is adaptable and grows happily in most soil types, including almost any reasonable soil — loam, chalk and sand or clay. It prefers acid and neutral or alkaline soil. Aim for soil that stays well drained but not parched.

How do I prune Geranium macrorrhizum?

Cut back to a low framework after the first flowering to renew the foliage and prompt repeat bloom. Tidy any remaining growth in late autumn or early spring.