[Bing]

I bought a thornless blackberry plant last year, but it reverted to normal plant with thorns, I cut them and found out later that I should not do that as it will come back to thornless after a year. Now this year, it growing with thorn again, and I don't know whether I should give it another year or just behead it and buy a new plant! It pi55 me off

[balfie]

Quick update, they are all growing very well, spreading all over the place!
And all are definately thornless.

From your replies, I think maybe I need to put supports in?
I have some black berries growing, but only a few.

I am going to leave them a bit longer and see what happens, but I am fairly tempted to get rid of them.
I dont really see the point of giving space to Blackberry bushes when there are so many of them growing wild.  But I will see how they go, and how I feel. 

[Headgardener22]

It al depends what sort they are of course. I've got thornless blackberries on my allotment (three different varieties) and they are sweeter than the wild ones

[clairebeau]

Well if it's anything like my pals I'd keep them!  Theirs have HUGE fruit on them and I'd heard about how sweet (but sometimes bland) they are but the ones I pinched last week were just the same taste as wild blackberries.
I was most certainly a green eyed monster!