Is this plant invasive?

It spreads by rhizomes but is generally considered well behaved and easy to manage.

Does it need full sun?

It prefers partial shade but will tolerate full sun if the soil remains moist.

Plant guide

Bigroot Geranium.

Geranium macrorrhizum

Pronounced jeh-RAY-nee-um mak-ro-RIH-zum

Also known as Bulgarian geranium, Rock Crane's-bill, big-rooted geranium, bigroot geranium, cranesbill, hardy geranium

Rock Crane's-bill — Photo by portioid (CC BY) via iNaturalist

This hardy perennial is a fantastic groundcover that handles shade and dry spells with ease. It features aromatic foliage and lovely pink to magenta flowers in late spring. You will love how it suppresses weeds while looking great in your garden.

Another photo of Bigroot Geranium — Photo by Christina (CC BY) via iNaturalist

At a glance

Care level: Easy
Plant type: Perennial
Light: Partial shade to full shade
Indoor light: Medium light
Water: Every 7 to 14 days
Mature size: 12 to 18 inches
Growth rate: Medium
Hardiness: USDA 4 to 8
Bloom time: Late spring to early summer

Care

Plant this geranium in well draining soil to keep the roots happy. Watch for wilting during extreme heat, though it is quite drought tolerant once established. You can tidy it up by removing spent flower stalks after the main bloom.

Watering: Water deeply when the top inch of soil feels dry to the touch.
Feeding: A light application of balanced compost in early spring is plenty.
Pruning: Cut back foliage in late autumn or early spring to encourage fresh growth.
Repotting: If growing in containers, move to a larger pot once the roots become crowded.
Soil: Well draining, average garden soil
Soil pH: 6.0 to 7.5
Temperature: -30 to 35°C
Humidity: 40 to 70%
Drought tolerance: High
Lifespan: Perennial, typically 10 plus years
Fragrance: Strong
Deer and rabbits: High

Signs it needs repotting

Roots growing out of the drainage holes
Water running straight through the pot
Growth slowing significantly

Safety

People: The plant is generally considered non-toxic, but ingestion is not recommended.
Children: The plant is not known to be dangerous to children, but it is always best to discourage eating garden plants.
Contact allergens: The glandular hairs on the leaves can cause mild skin irritation in sensitive individuals.
Airborne allergens: There are no significant reports of respiratory allergies associated with this plant.
Edibility: This plant is not considered edible and should not be consumed.

How to identify it

Deeply lobed, fragrant green leaves
Thick, spreading rhizomatous roots
Clusters of five petaled flowers
Distinctive reddish flower calyces
Semi evergreen foliage in mild climates

Height: 0.2 to 0.4m
Spread: 0.3 to 0.6m
Leaves: green, bronze, semi-evergreen
Flowers: pink, magenta, white, 2 to 3cm
Fruit: brown, Summer

Problems to watch for

Powdery mildew · A fungal infection that appears as white dusty spots on leaves during humid weather.

By symptom

Plant problems by symptom

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Growing it

Propagation: division, cuttings
When to plant: spring, autumn
Overwintering: Cut back dead or damaged foliage in late winter to make room for new spring growth.
In containers: It grows well in containers, provided the pot has good drainage and is at least 30 centimeters wide.

Division

1. Dig up a mature clump in early spring or autumn.
2. Gently pull the rhizomes apart into smaller sections.
3. Ensure each section has roots and healthy foliage.
4. Replant immediately in prepared soil.

Plant this geranium as a living mulch under shrubs to keep the soil cool and suppress weeds.

Grows well with

Hosta · They share similar shade requirements and provide contrasting foliage textures.
Ferns · The delicate fronds of ferns look beautiful against the rounded leaves of the geranium.

Similar species

Bloody Cranesbill · It is another hardy geranium but prefers more sun and has a more mounding habit.

Science

Family: Geraniaceae
Genus: Geranium
Order: Geraniales
Class: Magnoliopsida
Native range: Southern and central Europe.
Conservation: This plant is common in its native range and is not of conservation concern.

It thrives in woodland settings by forming dense colonies that shade out competing vegetation.

Value to wildlife: nectar source, ground cover habitat
Pollinators: bees, butterflies
Uses: ground cover, woodland garden, erosion control, weed suppression

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 1/9
Soil reaction: 6/9
Light: 4/9
Temperature: 5/9
Moisture: 4/9
Nutrients: 4/9

Taxonomy resolved against GBIF.

Questions people ask

Is this plant invasive?: It spreads by rhizomes but is generally considered well behaved and easy to manage.
Does it need full sun?: It prefers partial shade but will tolerate full sun if the soil remains moist.

Where the name comes from

The name Geranium comes from the Greek word geranos, meaning crane, referring to the beak-like fruit. Macrorrhizum means large-rooted, referencing its thick rhizomatous root system.

Good to know

It is often called Bigroot Geranium because of its thick, spreading rhizomes.
The leaves often turn a lovely bronze or red color in the autumn.
It is an excellent choice for dry shade where other plants struggle.
The plant forms a dense mat that effectively chokes out weeds.

Keep your bigroot geranium growing

This page is a general guide. Save your plant in Pocket Botanist and you get care reminders timed for this plant, plus a care history that shows what worked.

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This guide was generated with AI on October 19, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.