Bigroot geranium
Geranium macrorrhizum
A vigorous, semi-evergreen, clump- and colony-forming hardy geranium grown as one of the best groundcovers for dry shade under trees and shrubs. Its soft, deeply lobed, strongly aromatic leaves form a dense, weed-smothering carpet, many of them flushing red and bronze in autumn, and above the foliage rise loose clusters of magenta-pink (or white) flowers with prominent protruding stamens in late spring and early summer. It spreads steadily by thick surface rhizomes into a tough, low-maintenance, weed-proof mat that is easy to pull back and is not aggressively invasive. The aromatic foliage makes it markedly deer- and rabbit-resistant, and it is genuinely drought-tolerant once established. It is grown purely as an ornamental and is not a food plant.
Climate fit: narrow (39/100)
Border
Filler
Pollinator
Light
Full sun / Part shade
Water
Moderate water
Mature size
12-18" tall · 18" apart
Hardy in zones
4a-8b
very cold to frosty winters
Native in Illinois
No
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The early-season flowers, with their prominent protruding stamens, are an easy nectar and pollen source for honey bees and solitary bees when little else is open; named forms are propagated vegetatively by division to keep them true.
Cold hardiness
These values are location-based: this location's current hardiness is the baseline, and the 2050 value is a projected future climate for this same location.
Now
Zone 6b
Plotwright
USDA Zone 6b
-5°F to 0°F
Well-suited
Zone 7a
Plotwright
0°F to 5°F
Well-suited
In plain terms: This location has cold winters. Its winters are projected to keep warming through 2050.
✓
Well-suited today and still thriving in 2050.
Heat tolerance
Heat tolerance values are location-based too: heat days today are observed at this site, and the 2050 value projects this same location under a future climate.
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Where this plant fits
Suitable across 39 ecoregions - 31 climate-resilient through 2070 · 5 suited today · 3 newly possible by 2070. Best matches first.
Similar plants
Browse lateral options with similar roles, light needs, size, or native-range overlap; these are not filtered for a better climate fit.
Educator packet
Plant packet
Bigroot geranium educator packet
A vigorous, semi-evergreen, clump- and colony-forming hardy geranium grown as one of the best groundcovers for dry shade under trees and shrubs. Its soft, deeply lobed, strongly aromatic leaves form a dense, weed-smothering carpet, many of them flushing red and bronze in autumn, and above the foliage rise loose clusters of magenta-pink (or white) flowers with prominent protruding stamens in late spring and early summer. It spreads steadily by thick surface rhizomes into a tough, low-maintenance, weed-proof mat that is easy to pull back and is not aggressively invasive. The aromatic foliage makes it markedly deer- and rabbit-resistant, and it is genuinely drought-tolerant once established. It is grown purely as an ornamental and is not a food plant.
Scientific name
Geranium macrorrhizum
Plant type
perennial
Hardiness
4a-8b
Light
full-sun, part-shade
Moisture
moderate
Spacing
18 inches
Classroom prompts
- Which plant traits are observations, and which are care recommendations?
- How would this plant fit change if the garden location moved warmer, colder, wetter, or drier?
- Which source-backed facts would you cite in a lesson handout?
Use the Sources & citations section below for page citation styles and the field-level source list.
Sources & citations
Cite this page
For lesson plans, articles, or research that uses this page. Use the source cards below to explore the references that informed this record.
Plotwright. (2026, May 17). Bigroot geranium (Geranium macrorrhizum). Retrieved 2026, August 20, from https://plotwright.com/plants/geranium-macrorrhizum
Sources used for this record
This record is compiled from the sources below.





