blackberry containment?

[mellowtigger]

I completed another hour or two of gardening today before the sprinkling rain started to soak my shirt.

Does anyone know how to effectively contain a blackberry patch? I want blackberries. I'm not trying to eliminate them. I'm just trying to build an area in my yard that can keep them in bounds, so I don't have to spend a lot of time in future years trying to destroy the rambling roots.

Searching online, I find this estimate to their depth:
Blackberry can easily go a foot to a foot and a half deep even in clay soils.

That's about half a meter, for everyone on the planet but backward Americans.  If that depth is to be believed, then how can I contain them? I can easily buy cinder block and dig a path to place them, but then how do I seal the cinder block to prevent root growth between the blocks?

Comments

[bitterlawngnome]

You can't contain them under normal circumstances, cause even if you put them in a container with no soil contact, the birds eat the berries and spread the seed far and wide. Blackberries are the kudzu of the west coast. About all you can do is choose a less-invasive cultivar and keep hacking them back.

[zipperbear]

I had more problems with seedlings (by bird droppings, I assume). Blackberries in California spread mostly above-ground, with long canes. They'll put down roots eventually where they touch the soil, but easy enough to pull up (except that the branches and leaves are covered with thorns). Established root-clumps will keep sprouting every spring for a couple of years, but they're easy to mow or cut back. But we don't get rain in the summer, so they stop growing until fall. I've never seen much underground spreading.

I originally planted some thornless blackberries/raspberries, but the seedlings reverted to having thorns. They mostly bear fruit on year-old growth, and I tried holding them with twist-ties stapled to the fence in my side-yard, but they responded by growing perpendicular to the fence (toward the light, of course), blocking the walkway. They always got ripe in late June, just as I was leaving for vacation, so the birds got most of them.