think in terms of three years!
the first year canes (Primocanes) are green and grow no fruit. Second year, Floricanes, are more woody, grows fruit, then it does back in third year, almost white dead wood.
A good tip, in early spring, cut the tip off of a cane ONLY if it has NOT flowered yet. this forces the cane to grow branches out sides ways, giving you more branches and places for buds. Also, I tip I learned, cut off all the dead stalks, and cut those into 10cm-20cm bits. LEAVE them on ground underneath the other live canes. It acts as mulch and is the correct pH for the soil that the plants like to grow in.
I wonder if the trailing variety also follow this process, mine are not erect canes like you find with native Blackberries or Raspberries. My thornless variety are trailing. I did purchase a "semi-erect" variety. But I think all thornless blackberries need to be trellised or on some guide wires.
OK cool, I will try cutting the tip of the cane off next year and see if it grows out from it. Will do for the dead stalks too, but these are so young I doubt I will have many dead stalks for some time.
Good idea, will "chop and drop" the spent canes.
Thanks @bluefinstudios for the advise on these and for the tips on my Apple trees! I really appreciate the comments.
I personally like my canes to grow about mid chest. I cut them that height early spring. It gives me lots of fruit in summer and fall (right now).