Mexican Sunflower - Tithonia

Has anyone grown Mexican Sunflower, Tithonia rotundiflora?  I grew it from seed several years ago after seeing it at Tower Hill Botanic Garden.  You have got to love the bright orange, zinnia like flowers.  The first year I grew it in average garden soil and the plants grew to about four feet at the most.  Here my friend, Denise, is taking a nap next to them.  Her outfit does match them quite nicely and she provides nice scale and proportion for the plant.  She is of average height.
The plants were unfazed by warm, dry weather and, in fact, they did thrive in those conditions.  You know how it goes with many annuals, you try them, like them, and then make room to try something else.  Tithonia has been on my list to plant again and this year a friend gave me two plants which she started from seed.  I put them in the flower bed right in front of the living room window since this plant does attract bees, butterflies and hummingbirds and I often watch from inside.   Who knew what would happen.  They are making a nice green curtain right about now.  
 Outside the house, they are the large plants on either side of the birdfeeder, closest to the house, and towering over the roof.  They have had just two flowers so far and they have required rebar stakes to keep them  somewhat upright.  I use an organic fertilizer but not in excess and they really are being stingy with the flowers this year.  I am hoping they will light up like a jack o'lantern well before Halloween since the frost will get them by then.  We shall see.  Now, I am waiting to see just how tall they will grow.  Has anyone had them get this tall and, if so, did they have lots of flowers?  Just wondering.....