Probably best to do over Winter when they are dormant and to trim off most
of the top growth first. Take as much of the root ball intact as possible.
I've got a cultivated bramble (very large blackberries) that I planted in
the wrong place and it either needs moving or maybe I'll try taking some
cuttings by layering instead and plant those elsewhere.

Alternatively you could simply plant some blackberry seeds, but the
offspring may not come true.

Given I have no idea what these plants are anyway, other than tasty and
scattered around my garden, I doubt they were true in the first place ;-).

Thanks for the advice. I have considered layering but given how many plants
I've already identified, loosing a few will not be an issue.

Paul DS