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Poa annua L.
Winter Grass

Sp.Pl. 1:68 (1753)
Conservation Code
Not threatened
Naturalised Status
Alien to Western Australia
Name Status

Tufted annual, grass-like or herb, 0.02-0.4 m high. Fl. green, Aug to Dec or Jan to Feb. White, grey, black or peaty sand, sandy clay, sandy loam. Lawns, disturbed areas, swamps, outcrops.

Grazyna Paczkowska, Descriptive Catalogue, 3 December 1993


IBRA Regions
Avon Wheatbelt, Coolgardie, Esperance Plains, Geraldton Sandplains, Hampton, Jarrah Forest, Mallee, Swan Coastal Plain, Warren.
IBRA Subregions
Dandaragan Plateau, Eastern Mallee, Fitzgerald, Geraldton Hills, Hampton, Katanning, Lesueur Sandplain, Mardabilla, Merredin, Northern Jarrah Forest, Perth, Recherche, Southern Cross, Southern Jarrah Forest, Warren, Western Mallee.
IMCRA Regions
Abrolhos Islands, Central West Coast, Leeuwin-Naturaliste, Shark Bay, WA South Coast.
Local Government Areas (LGAs)
Albany, Armadale, Augusta Margaret River, Belmont, Busselton, Canning, Capel, Chapman Valley, Chittering, Cockburn, Coolgardie, Coorow, Cranbrook, Dandaragan, Dardanup, Denmark, Dowerin, Dundas, Esperance, Gingin, Gosnells, Greater Geraldton, Harvey, Joondalup, Kalamunda, Kent, Kulin, Manjimup, Melville, Murray, Nannup, Narrogin, Nedlands, Northam, Northampton, Perth, Ravensthorpe, Rockingham, Serpentine-Jarrahdale, Shark Bay, South Perth, Stirling, Swan, Vincent, Wandering, West Arthur, Yilgarn.

Management Notes (for the Swan NRM Region)

Alternative Names. Annual blue grass, bluegrass, annual meadow grass.

General Biology. Growth form. Grass. Life form. Annual, caespitose. Reproduction. Seed. Dispersal. Wind, water, birds, contaminated seed, on footware and clothing, mowers and other equipment. Photosynthetic Pathway. C3. Seedbank persistence. 4-6 years.

Notes. Generally a weed of disturbed sites usually with limited impact on native plant communities. Survives as a weed due to high genotypic and phenotypic variability, rapid germination, survival when uprooted and tolerance to compacted soils. Grows aggressively under moist conditions, good levels of soil nitrogen and phosphate and is not adversely affected by most mowing heights. Tolerates a wide range of climatic conditions, making it a potentially invasive species for a range of areas including the Sub-Antarctic Islands. Can flower and establish at any time of the year, although this is less likely under dry conditions. Generally has high seed production. Seed has generally high viablity and staggered germination. Most seed germinates within the first year and when soil is wet during the winter months.

Additional information. History of use/introduction. Potential seed contaminant. Similar exotic species. Poa pratensis.

Suggested method of management and control. Light infestations can be hand weeded. Susceptible to many herbicides, however some grass-selective herbicides such as fluazifop (Fusilade® Forte) can give poor control. Read the manufacturers' labels and material safety data sheets before using herbicides. For further information consult the Australian Pesticides and Veterinary Medicines Authority to determine the status of permits for your situation or state.

Management Calendar

Calendar Type Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Comments
Fruiting O O O O Y Y Y Y Y Y Y Y  
Active Growth O O O O Y Y Y Y Y Y Y O  
Flowering O O O O O O O O O Y Y Y  
Manual Removal           Y Y Y Y Y Y Y  
Herbicide Treatment           Y Y Y Y Y O O  

Legend: Y = Yes, regularly, O = Occasionally, U = Uncertain, referred by others but not confirmed.



  • Brown, K. & Brooks, K. (2002) Bushland Weeds: A Practical Guide to their Management. Environmental Weeds Action Network, Greenwood.
  • Carr, G.W., Yugovic, J.V. & Robinson, K.E. (1992) Environmental weed invasions in Victoria. Department of Conservation and Environment, Melbourne.
  • Hussey, B.M.J., Keighery, G.J., Dodd, J., Lloyd, S.G. & Cousens, R.D. (2007) Western Weeds. A guide to the weeds of Western Australia. 2nd Edition. The Plant Protection Society of Western Australia, Victoria Park.
  • IUCN SSC Invasive Species Specialist Group (ISSG) (2009) Poa annua (grass), Global Invasive Speceis Database. URL: - Accessed January 2010.
  • Law, R. (1981) The dynamics of a colonizing population of Poa annua. Ecology, 62 (5): 1267-1277.
  • Law, R., Bradshaw, A.D. & Putwain, P.D. (1977) Life history variation in Poa annua. Evolution, 31 (2): 233-246.
  • Lawson, H.M., Wright, G.M., Wilson, B.J. & Wright, K.J. (1993) Seedbank persistence of five arable weed species in autumn-sown crops. In Brighton crop protection conference, weeds. Proceedings of an international conference, Brighton, UK, 22-25 November 1993. 1: 305-310.
  • McElroy, J.S., Walker, R.H. & Wehtje, G.R. (2004) Annual Bluegrass (Poa annua) populations exhibit variation in germination response to temperature, photoperiod and fenarimol. Weed Science, 52: 47-52.
  • Mitch, L.W. (1998) Annual bluegrass (Poa annua L.). Weed Technology, 12 (2): 414-416.
  • Scott, J.J. & Kirkpatrick, J.B. (2005) Changes in Subantarctic Heard Island vegetation at sites occupied by Poa annua. Artic, Antarctic and Alpine Research, 37 (3): 366-371.
  • Shem-Tov, S. & Fennimore, S.A. (2003) Seasonal changes in annual bluegrass (Poa annua) germinability and emergence. Weed Science, 51: 690-695.
  • Suzuki, M. (1994) Observation of germination ability of upland weeds buried into soil at a 30 cm depth during 25 years. Weed Research, 39 (1): 34-39.