Found my answer:
Grass While purple fountain grass is known as a perennial, it is actually considered a tender perennial. This ornamental grass cannot survive cold winters and is hardy only in USDA Plant Hardiness Zones 9 and warmer (though in Zones 7-8 it can sometimes reappear given adequate winter protection). Therefore, it is important that this be a consideration prior to planting purple fountain grass, as the likelihood of its return each year in zones 6 or lower is slim to none. In fact, in cooler regions the plant is normally treated as an annual instead. However, it is still possible to enjoy this
Read more at Gardening Know How: Growing Purple Fountain Grass – How To Take Care Of Purple Fountain Grass
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