Geranium macrorrhizum is a species of hardy flowering herbaceous perennial plant in the genus Geranium, family Geraniaceae. It is native to the South east Alps and the Balkans. Its common names include bigroot geranium, Bulgarian geranium, and rock crane's-bill.
It has five-lobed (palmate) leaves that are aromatic when crushed, with pale pink flowers in summer. It is cultivated as an ornamental plant in temperate regions, where it is used as a flowering groundcover, with named cultivars selected for flower colors from white through pink to magenta. The cultivars 'Ingwersen's Variety' (pale pink) and 'White-ness'  have gained the Royal Horticultural Society's Award of Garden Merit.
The plant has been used in traditional herbal medicine. The name for all types of geraniums in general in the Bulgarian language is derived from the word здрав, which can translate as 'healthy', among a few related concepts. An essential oil from it is also used in aromatherapy. In addition to oils, it contains flavonoids, sesquiterpenes, phenolic acids, pigments, vitamins, and mineral salts.
One of the many components of the essential oil is the sesquiterpene ketone germacrone, which has been shown to have a high and selective antimicrobial activity against the species Bacillus subtilis.
- RHS A-Z encyclopedia of garden plants. United Kingdom: Dorling Kindersley. 2008. p. 1136. ISBN 978-1405332965.
- "Geranium macrorrhizum". Germplasm Resources Information Network (GRIN). Agricultural Research Service (ARS), United States Department of Agriculture (USDA). Retrieved 19 January 2018.
- BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-06-26. Retrieved 2014-10-17.
- "RHS Plant Selector - Geranium macrorrhizum 'Ingwersen's Variety'". Retrieved 5 July 2020.
- "Geranium 'White-ness'". RHS. Retrieved 14 July 2020.
- "AGM Plants - Ornamental" (PDF). Royal Horticultural Society. July 2017. p. 43. Retrieved 2 March 2018.
- Niko S Radulović, Milan S Dekić, Zorica Z Stojanović-Radić, Suad K Zoranić. Geranium macrorrhizum L. (Geraniaceae) essential oil: a potent agent against Bacillus subtilis. Chemistry biodiversity (2010). Volume: 7, Issue: 11, Pages: 2783-2800