Since acres are not a unit of length, I assume your ditch is hundreds of feet long, as an acre, if square, is about 210 feet on a side.

Why not try wax myrtles or pittosporum. Both grow very fast and do not spread by runners. If you get a pittosporum that produces seed (not all do) you need to cut it out as it will populate your entire neighborhood with seedlings. Wax myrtle will drop seed, too, but does not seem to spread like the pittosporum.

still kris, those plants are not hardy in Montana.
Mike

If you havent' yet, you might want to post this one on the GardenWeb Rocky Mountain Gardening forum.

Thank you for responding. Yes I would say the ditch is no less than 500 feet or so. In farming country we tend to think in acres.

Yes, bboy I should have posted on the rocky mountain forum or the far north one. I will do it now.

thanks again. By the way...I'm thinking of a bamboo hedge...P. Nuna. It's supposed to be root hardy in zone 4, and leaf hardy in zone 5...although opinions do vary, I thought I'd give it a try.

(the topic has not appeared on the Rocky, Far_N, or Bamboo forums as of yet)

That much bamboo would cost a fortune here. Try just a couple of clumps--may not do well in a bone-dry ditch. Is there other bamboo in the area?

A series of Burma Shave signs would distract passers-by and divert their eyes from looking further back.

Won't the cottonwoods sprout anyway? You might want to see if this happens before you spend a lot of money on a new hedge. They won't stop growing here even if cut down several times.