I have no personal experience with Navaho in Zone 5, but I did avoid it based on research. I have Chester which I think is kind of a stinker, and just last month planted Illini Hardy and Triple Crown. The Illini is already growing nicely. I believe warmer zone berries like TC will be successful only if given winter protection somehow via mulch or temporary coverings or whatever. Navaho might be a similar story. I am not sure.

It going to be hard to cover an upright blackberry. You can't put it on the ground! If you're plants are rated for zone 6 they should be OK, unless you regularly have temps below -5 degrees. Plants rated for zone 6 can handle anything above -5 degrees.

If you want to grow them without making any special effort to protect them during winter, then I would pass. The hardiest variety I've heard of (apart from some wild-sounding internet claims) is "Balsor's Black" out of Nova Scotia, supposedly zone 4, but I've never tried it myself. You might have a hard time finding it in the US.

I'm in zone 3 and I grow Chester (this will be year 5 for the oldest plant). But I lay down the canes in early November and cover them with a deep layer of straw and burlap until April, and even then there is quite a bit of winterkill. So I'm sure you could grow them if you are willing to go high-maintenance, otherwise I wouldn't bother.

Another option would be against the south wall of your house if you wanted to do that, and had the room.

There might be just enough extra warmth from the foundation to make it work.

Thank you all so much for confirming my thought. Everyone kept telling me the bush would be fine. I kind of thought I should believe the tag. My present is going back to the store. Oooh, wonder what I should get in it's place?!!!

How about black rapspberry (aka blackcaps)? These are so underappreciated, being hardy, vigorous, prolific, and delicious (and black like blackberries!).

One thing to keep in mind as well - blackberries (like all brambles) have biennial canes and perennial roots. So if you're marginal zone-wise, you might have some years where you lose the fruiting canes, & others where you don't. Unlike a fruit tree like a peach or cherry, you don't have to start over due to winterkill - the root crown is likely to be able to survive temps colder than the canes can, especially if there is some snowcover. After a hard winter, you might lose the above-ground (fruiting) portion, but that summer, your crowns will send up new canes that hopefully will survive the following winter.

If you can deal with getting crops maybe 2 years out of 4 or so, then go for it.

I know of someone in zone 5 (Michigan) growing boysenberries, (I assume the thorny ones since the thornless ones don't even fruit here in z7 due to lack of hardiness). He gets a crop about 3/5 of the time. However, the root crowns always send up lots of primocanes each year, so even if he loses a crop, the plants survive.

The primocane blackberries fruit on 1st year wood, so it is possible to get some harvest every year. they are good eating too from what people say. I want to add one just for taste, and to check out primocanes, but I have a very long want list of desired blackberries and hybrids.

Was it the W store? They had blueberries last spring, recommended for zone 7...and we're in zone 4, store location is zone 5.

Try "chester". Mine was planted near a south wall. The snow here managed to weigh it down and protect it. I cant get rid of the damn thing lol. It is not an upright variety and I had canes almost 12 feet long (unpruned). I never had a problem with it dying back as long as you make sure that there is a good load of snow, and that it is against or near a wall, preferably south. I dont have experience growing it in an exposed area so i cant say much in that aspect.

I also have boysenberries, and they are definitely as prolific as the blackberries. They are pretty much thornless, and have fruited 3 times. Again they are set up in a similar area. I dont think the upright varieties would do as well since they would be exposed.