Planting blackberries help

I have just ordered two blackberry plants.  One Loch Ness and one Waldo.

Someone on my allotment suggested putting in two six foot posts 1.5 meters apart and running wire across for the plants to grow up.  Is this the way to go?

I have never grown blackberries before so any advice on how to plant and support them would be helpful. 

That would probably do for the first couple of months!

Just add more posts & wires thereafter.

Just out of interest how much, and how quickly do these plants grow/spread?  How much space should I allow for them?

Just out of interest how much, and how quickly do these plants grow/spread?  How much space should I allow for them?

Space - as much as you want!

I planted a Loch Ness 2 years ago. It's gone about 8 feet in either direction and accelerating!

Hi, you'll be surprisedat the size of loch ness they're huge i stretch wires across the width of my lotty plant iether side and let them meet in the middle.

I planted 4 black berry plants this year, about 4 months ago, so far this is happened.

Merton Thornless: very healthy looking about 3 foot high and 4 foot across, would be bigger got attacked by snails.  (I now hate snails)

Waldo: is still a little bush but is very healthy looking but growing at a slower pace.

Lockness: 2 stems which I'm having a hard time to keep alive.

Tayberry: Oh my god this thing is going to take over my garden, so far 8 foot high, and 5 foot across, already had about 15 berrys of it, I was not going to even bother planting it in my garden, as some have said the berry crop can be quite low, but so far so good.