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Ageratum

Ageratum houstonianum
Also known as Floss Flower, this native to Mexico and adjacent Central America was discovered by William Houston (c. 1695-1733), a Scottish botanist, plant collector, and ship’s surgeon. Houston sent seeds to England in the early 18th century, and British author Philip Miller referenced the species in a 1768 edition of his Gardener’s Dictionary. It was first documented in American gardens in 1836. This self-seeding species forms a spreading, loose-growing plant. The pale blue, and occasionally white, tassel-like flowers bloom from midsummer until the first autumn frost.The Ageratum at Monticello is tall-growing and is not to be confused with the dwarf bedding types now popular.
Visit Monticello’s Online Shop to check for seeds or plants of Ageratum.
Growth Type: 
Annual
Color(s): 
Purple, Blue, Pink, White
Hardiness Zones: 
Zone 1, Zone 2, Zone 3, Zone 4, Zone 5, Zone 6, Zone 7, Zone 8, Zone 9, Zone 10
Location at Monticello: 
West Lawn
Planting Conditions: 
Partial Shade
Blooming History: 
June 14, 2001 to November 8, 2001July 5, 2002 to November 8, 2002July 17, 2003 to November 14, 2003July 19, 2004 to December 3, 2004July 20, 2005 to November 15, 2005June 30, 2006 to November 15, 2006July 6, 2007 to November 15, 2007July 11, 2008 to November 17, 2008July 10, 2009 to November 15, 2009June 28, 2010 to December 2, 2010June 28, 2011 to December 6, 2011June 29, 2012 to December 4, 2012July 11, 2013 to November 15, 2013June 16, 2014 to November 21, 2014June 15, 2015 to November 24, 2015June 17, 2016 to November 12, 2016June 30, 2017 to November 10, 2017June 20, 2018 to November 12, 2018June 25, 2019

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