Seems to be most invasive in warmer, mild winter climates but has the potential for being invasive anywhere it grows when planted adjacent to any sort of body of water - streams, lakes rivers, etc. Digging it out is the best way to remove.

Probably won't be hardy in USDA 5 anyway.

There are various previous theads on this forum that report growing Arundo donax successfully in colder zones.

IT is HUGELY invasive in Texas.

Have my Arundo donax 'Variegata' for more than than 5 years (including two really bad practically Zone 4-liked winters), but it did not spread at all unlike some Miscanthus; probably because the area was dry.

I have heard that the variegated one is less aggressive.

There are various previous theads on this forum that report growing Arundo donax successfully in colder zones.

As always with unexpected hardiness claims key points are:

- Which "colder zones", specifically?

- "Successfully" for how long, specifically? Short term persistence does not establish general or long term suitability. And was special protection being used, like deep mulching in this case? Many (most?) people asking about plants are not dedicated hobbyists willing to coddle them to any serious extent.

Otherwise the Missouri Botanical Garden for instance considers this plant on the border of cold tolerance in USDA 6-7. I've grown it in a couple locations in USDA 8 and even there the tops may get hammered during the winter. Yet in milder zones it is evergreen.

http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=285183

Zone 4 and for multiple years. Even a previous post upthread reports growing it in zone 5 for more than 5 years.

In 8b , I see it topping off around 20' if it has good moisture. We have the worst problems with it around river banks. Getting rid of a stand is proving very difficult if it get a hold in a clump. Burning combined with chemicals.

Arrondo Donax Invassive institute