[Tilted Irish Kilt]

greeneyes:" I’d like to have a thicket of Rosa Rugosa around the perimeter of our little acre lot.
It’s supposed to spread enough to make a nearly impenetrable barrier."

Yes , the Rugosa can form an impenetrable barrier if planted in spaced alternate wide rows ; sorta like the interlock of a zipper.
Caution advised : the 5 to 6 foot canes are armed with thorns that will penetrate all but the most armoured outdoor clothing. I know from Deer hunting .
If planted thick enough, it can be a living flowering hedgerow for wildlife and birds ; a sanctuary providing shelter and food (rose hips).
Cooperative Extension frequently has low cost 'bare root' plantings available in the Spring in lots of 50 plants @.
Propagation is by cane tips touching the ground, then rooting into the soil can become invasive; best to keep in range of electric hedge clippers .. lol.

[greeneyes]

Good info. Thanks.

[tillacum]

So it’s a good idea to kind of trim the bottom branches too, from time to time?