I agree it looks like Holcus lanatus, the only thing which I was unsure of is the height of around 5 feet. I doubt it could reach that height even in the most favourable conditions.
http://keyserver.lucidcentral....
This species can be distinguished from H. mollis by the beardless nodes on its culm, the absence of rhizomes, and the awn becoming hooked when dry and not projecting beyond the tips of the glumes
https://en.wikipedia.org/wiki/...
http://www.thewildflowersociet...
http://canope.ac-besancon.fr/f...
http://canope.ac-besancon.fr/f...
Holcus mollis doesn't usually have the purple colouring, nor does it grow to 5 feet tall.
http://www.plant-identificatio...
The height is still a worrying factor, is there a similar looking species of grass?
