Many of us are familiar with ageratum, the low-growing annual with fuzzy flowers that are blue/lavender color. It is a member of the Ageratum genus that includes 43 species of annuals and perennials, most of which are native to warmer regions of the American continents. 

They have felted oval or heart-shaped leaves and clustered flower heads. They like full sun and moist well-drained soil, and a common name is floss flower. Another common name is billy goat weed, which suggest perhaps that goats may like them. I am guessing about that, as I have never seen a goat eating ageratum in my garden. Of course, I do not have any goats in my garden, even though I do have ageratum, as it pairs well with just about any other plant of any color. 

I also grow tall varieties ‘Bavaria’ and ‘Blue Horizon’, which are 18-20 inches tall and produce good cut flowers that dry well. 

Some species of ageratum can be pink and white as well as blue. Some even grow in light shade—for example, Ageratum altissima, which gets quite tall and has fluffy white blossoms. 

Some native varieties of ageratum winter over in our zone 6 and may become a pest as they self-sow prolifically. As long as you just grow varieties of this plant that are annual in our cold climate, however, it is well behaved. Otherwise, you may need to get some goats!