If you're nervous about blackberries spreading, plant a variety like Triple Crown, Doyle or Chester. They will not spread via their roots like raspberries will. The ones that have native American sounding names will spread from their roots.

Yes, I keep my raspberries contained by mowing around them and you can do the same with root-spreading blackberries. If you wantted to try a phyical barrier, you need to go down deep. The actual depth depends on who you ask, but I would go down at least 12-15 Inches.

Yes, trailing varieties need more room than erect varieties. I would allow at least 4'+ on either side of a trailing variety, and at least 3-4' on either side of an erect variety.

You can the trellises and varieties I grow on my "mypage".
-Glenn

Untended blackberries can take over the entire area but it is a simple matter to prevent that. The way blackberries spread is by sending out arching canes whose tips eventually touch the ground, take root, and start whole new plants, each of which spread out in turn. If you take care of your plants, that won't happen. Keep them up on a trellis, or trimmed off the ground, remove the old canes after bearing fruit, and no problem. Piece of cake, really.
I will add that Apache does have a habit of popping up shoots from roots a good distance from the main plant, so I would avoid that one if your concerned about containment.
Do the trailing varieties take more space? Not really. Some of the upright varieties will become enormous. The main difference being that the trailing varieties have thin, flexible canes that can be easily wrapped around a trellis. The upright blackberries have thick, stiff, fibrous canes that would break if you attempted to bend them. The laterals that sprout from them, however, are thinner and can be positioned as you like.

The above advice is excellent.

Probing further:

What quantity of fruit do you want from your blackberries?
If you are sticking with one plant, the above-mentioned Triple Crown or Chester varieties, kept pruned to a few feet in each direction, could give you gallons of berries.

Great advice - thank you everyone!

As far as quantity of fruit - enough for 3 berry loving kids to stuff their mouths full of berries;) It's part of a little children's garden space I'm planning in the back yard.

I've heard the taste of the Triple Crown is pretty good - I'll look into the specifics of this one:) Thanks!

Just be careful while picking!

I have quite a bit of wild blackberries on my property (enough that I always put several gallons of berries in the chest freezer every year), and I am convinced we have caught this plant in the act of becoming carnivorous.

They produce tasty fruit, and all of the thorns point inwards towards said fruit. Means you can reach in and pick the fruit without any trouble, but you'll lose half your arm trying to pull it back out.

There is no good reason for this unless the plant is as actively trying to eat you as you are trying to eat it. It just hasn't learned how to chew yet. =P

I know I'm stirring the pot, but with so many premiere thornless berries, I see no reason to donate any more blood to the thorny varieties. I retained one patch of wild berries on my property, but I think next year it may go the way of the bush hog. I do have Prime Jim and Jan more out of curiosity, but if they don't satisfy, TC's will replace them. Still, the worst thorns are probably black raspberries---but I don't mind bleeding for them. Gooseberries pack a wallop too!

Brook

I'm with Brook. With great tasting thornless varieties like Triple Crown and Doyle, I have no reason to go with the thorned varieties. They are just too vicious for me. Plus, I prefer these varieties because they only tip-root, which I can easily control, instead of root-spreading which I can't as easily.

Agreed on the black raspberries. I'm wondering when research will provide a thornless variety of them! Also agree on the gooseberries!
-Glenn

Oh goodness! I was not even considering getting a thornless variety!!! I've heard that the more recent varieties like Triple Crown were just as tasty as the prickly ones.

I like my thorned wild blackberries. I warn people ahead of time that "These aren't your pansy little walmart blackberries, these'll bite back!"

lol - I meant to say that I was not considering getting a THORNED variety... sheesh - my comments are certainly living up to the title of this thread, aren't they!?!

Looking for thornless blackberries to plant:)

Edymnion-
Even though I haven't/wouldn't plant any thorned variety, I have TONS of wild ones right in back of my house. I used to like them, because I didn't know any better. But now, when compared with my cultivated varieties, the berries are much smaller, very seedy, and no where near as sweet (bitter infact), while the canes have vicious thorns.

On the pansy side, I have no problem dissing any plant from Walmart, but I would say that my cultivated blackberries have even thicker stronger canes than the wild ones... but admittedly that's likely because I treat them so well (lots of sunlight, good spacing, nice trellis, compost, etc)

All that said, I just planted a 'Wild Treasure' from Raintree based on Scott Smith's recommendation. It's supposed to have some of that wild flavor (not as sweet), yet is tip-rooting only (like TC), and still thornless. We'll see how it turns out.

I planted a blackberry plant last year that I bought from Home Depot. I don't remember if the label said what variety it was, but its definitely thornless and erect. Last year it sent up one primocane shoot and this year I see another one coming up. How many new shoots typically come up in a season? Will more come up later this spring/summer or do they all emerge around the same time?

My grandfather has several plants that he propagated from cuttings from a neighbor's plant 10-15 years ago and he seems to get a ton of new canes every year. Maybe he has the root propagating varieties that were mentioned earlier in the post? Perhaps one of the ones with a native American name?

Hi Parkville-
Some blackberries propagate by root-spreading others spread by tip spreading. Without knowing which variety you have, it's hard to say. Since it's thornless and erect, it could likely be Chester. If so, a mature plant will likely send up 3-6 good size canes each year, all around the same time. -Glenn

I don't know the name of my blackberry plant but it is thornless. My problem is that it is pulling up out of the soil on one side do I need to take it out and replant it a little deeper and use 2 canes or poles for support instead of one